]> Orange

mohamed.boucadair@orange.com

Juniper

rroberts@juniper.net

Telefonica

oscar.gonzalezdedios@telefonica.com

Nokia

samier.barguil_giraldo@nokia.com

Huawei Technologies

lana.wubo@huawei.com

Operations and Management Operations and Management Area Working Group Slice Service L3VPN L2VPN This document specifies a network model for attachment circuits. The model can be used for the provisioning of attachment circuits prior or during service provisioning (e.g., Network Slice Service). A companion service model is specified in . The module augments the Service Attachment Point (SAP) model with the detailed information for the provisioning of attachment circuits in Provider Edges (PEs). Discussion Venues Discussion of this document takes place on the Operations and Management Area Working Group Working Group mailing list (opsawg@ietf.org), which is archived at . Source for this draft and an issue tracker can be found at .

Introduction The procedure to provision a service in a service provider network may depend on the practices adopted by a service provider, including the flow put in place for the provisioning of advanced network services and how they are bound to an attachment circuit. For example, the same attachment circuit may be used to host multiple services. In order to avoid service interference and redundant information in various locations, a service provider may expose an interface to manage ACs network-wide. Customers can then request a base attachment circuit to be put in place, and then refer to that base AC when requesting services that are bound to that AC. specifies a data model for managing ACs as a service. This document specifies a network model for attachment circuits ("ietf-ac-ntw"). The model can be used for the provisioning of attachment circuits prior or during service provisioning (e.g., Network Slice Service). The document leverages and by adopting an AC provisioning structure that uses data nodes that are defined in these RFCs. Some refinements were introduced to cover, not only conventional service provider networks, but also specifics of other target deployments (cloud, for example). The AC network model is designed as an augmnetation to the Service Attachment Point (SAP) model . An AC can be bound to a single or multiple SAPs. Likewise, the model is designed to accomdate deployments where a SAP can be bound to one or multiple ACs.

Attachment Circuits Examples

The AC network model uses the AC common model defined in . The YANG data model in this document conforms to the Network Management Datastore Architecture (NMDA) defined in .

Conventions and Definitions The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 when, and only when, they appear in all capitals, as shown here. The reader should be familiar with the terms defined in . This document uses the term "network model" as defined in . The meanings of the symbols in the YANG tree diagrams are defined in . This document uses the following terms:

Bearer:

A physical or logical link that connects a customer node (or site) to a provider network. A bearer can be a wireless or wired link. One or multiple technologies can be used to build a bearer. The bearer type can be specified by a customer.

The operator allocates a unique bearer reference to identify a bearer within its network (e.g., customer line identifier). Such a reference can be retrieved by a customer and used in subsequent service placement requests to unambiguously identify where a service is to be bound.

The concept of bearer can be generalized to refer to the required underlying connection for the provisioning of an attachment circuit. One or multiple attachment circuits may be hosted over the same bearer (e.g., multiple VLANs on the same bearer that is provided by a physical link).

Network controller:

Denotes a functional entity responsible for the management of the service provider network.

Service orchestrator:

Refers to a functional entity that interacts with the customer of a network service. The service orchestrator is typically responsible for the attachment circuits, the Provider Edge (PE) selection, and requesting the activation of the requested service to a network controller.

Service provider network:

A network that is able to provide network services (e.g., Network Slice Services).

Service provider:

A service provider that offers network services (e.g., Network Slice Services).

Customer Terminating Point (CTP):

Refers to a customer-owned endpoint that terminates an attachment circuit. Such an endpoint can be a Customer Edge (CE), a Network Function (NF), a peer ASBR, etc.

Sample Uses of the Attachment Circuit Data Models shows the positioning of the AC network model in the overall service delivery process.

An Example of the Network AC Model Usage

Description of the Attachment Circuit YANG Module

Overall Structure of the Module The overall tree structure of the module is shown in . A node can host one or more SAPs as per . Each SAP terminate one or multiple ACs. The SAP model in is thus augmented with required AC-related information. Also, in order to ease the correlation between the AC exposed at the service layer and the one that is actually provisioned in the network operation, a reference to the AC exposed to the customer ('ac-ref') is stored in the 'ac-ntw' module. Unlike the AC service model, an AC is uniquely identified within the scope of a node not a network. An AC can be characterized using Layer 2 connectivity, Layer 3 connectivity, routing protocols, OAM, and security considerations. In order to factorize a set of data that is provisioned for a set of ACs, a set of profiled can be defined at the network level, and then called under the node level. The information contained in the profile are thus inherited, unless the corresponding data node is refined at the AC level. In such as case, the value provided at the AC level takes precedence over the global one.

Overall Tree Structure /nw:networks/network/ac-profile/name +--rw description? string +--rw l2-connection | ... +--rw ip-connection | ... +--rw routing-protocols | ... +--rw oam | ... +--rw security ... ]]>

The full tree of the 'ac-ntw' is provided in .

L2 Connection The Layer 2 connection tree structure is shown in .

Layer 2 Connection Tree Structure /nw:networks/network/ac-profile/name +--rw description? string +--rw l2-connection | +--rw encapsulation | | +--rw encap-type? identityref | | +--rw dot1q | | | +--rw tag-type? identityref | | | +--rw cvlan-id? uint16 | | | +--rw tag-operations | | | +--rw (op-choice)? | | | | +--:(pop) | | | | | +--rw pop? empty | | | | +--:(push) | | | | | +--rw push? empty | | | | +--:(translate) | | | | +--rw translate? empty | | | +--rw tag-1? dot1q-types:vlanid | | | +--rw tag-1-type? | | | | dot1q-types:dot1q-tag-type | | | +--rw tag-2? dot1q-types:vlanid | | | +--rw tag-2-type? | | | dot1q-types:dot1q-tag-type | | +--rw priority-tagged | | | +--rw tag-type? identityref | | +--rw qinq | | +--rw tag-type? identityref | | +--rw svlan-id uint16 | | +--rw cvlan-id uint16 | | +--rw tag-operations | | +--rw (op-choice)? | | | +--:(pop) | | | | +--rw pop? uint8 | | | +--:(push) | | | | +--rw push? empty | | | +--:(translate) | | | +--rw translate? uint8 | | +--rw tag-1? dot1q-types:vlanid | | +--rw tag-1-type? | | | dot1q-types:dot1q-tag-type | | +--rw tag-2? dot1q-types:vlanid | | +--rw tag-2-type? | | dot1q-types:dot1q-tag-type | +--rw (l2-service)? | | +--:(l2-tunnel-service) | | | +--rw l2-tunnel-service | | | +--rw type? identityref | | | +--rw pseudowire | | | | +--rw vcid? uint32 | | | | +--rw far-end? union | | | +--rw vpls | | | | +--rw vcid? uint32 | | | | +--rw far-end* union | | | +--rw vxlan | | | +--rw vni-id uint32 | | | +--rw peer-mode? identityref | | | +--rw peer-ip-address* inet:ip-address | | +--:(l2vpn) | | +--rw l2vpn-id? vpn-common:vpn-id | +--rw l2-termination-point? string | +--rw local-bridge-reference? string | +--rw bearer-reference? string | | {vpn-common:bearer-reference}? | +--rw lag-interface {vpn-common:lag-interface}? | +--rw lag-interface-id? string | +--rw member-link-list | +--rw member-link* [name] | +--rw name string +--rw ip-connection | ... +--rw routing-protocols | ... +--rw oam | ... +--rw security ... ]]>

IP Connection The Layer 3 connection tree structure is shown in .

IP Connection Tree Structure /nw:networks/network/ac-profile/name +--rw description? string +--rw l2-connection | ... +--rw ip-connection | +--rw l3-termination-point? string | +--rw ipv4 {vpn-common:ipv4}? | | +--rw local-address? | | | inet:ipv4-address | | +--rw prefix-length? uint8 | | +--rw address-allocation-type? | | | identityref | | +--rw (allocation-type)? | | +--:(dynamic) | | | +--rw (address-assign)? | | | | +--:(number) | | | | | +--rw number-of-dynamic-address? uint16 | | | | +--:(explicit) | | | | +--rw customer-addresses | | | | +--rw address-pool* [pool-id] | | | | +--rw pool-id string | | | | +--rw start-address | | | | | inet:ipv6-address | | | | +--rw end-address? | | | | inet:ipv6-address | | | +--rw (provider-dhcp)? | | | | +--:(dhcp-service-type) | | | | | +--rw dhcp-service-type? | | | | | enumeration | | | | +--:(service-type) | | | | +--rw (service-type)? | | | | +--:(relay) | | | | +--rw server-ip-address* | | | | inet:ipv6-address | | | +--rw (dhcp-relay)? | | | +--:(customer-dhcp-servers) | | | +--rw customer-dhcp-servers | | | +--rw server-ip-address* | | | inet:ipv6-address | | +--:(static-addresses) | | +--rw primary-address? | | | -> ../address/address-id | | +--rw address* [address-id] | | +--rw address-id string | | +--rw customer-address? inet:ipv6-address | +--rw ipv6 {vpn-common:ipv6}? | +--rw local-address? | | inet:ipv6-address | +--rw prefix-length? uint8 | +--rw address-allocation-type? | | identityref | +--rw (allocation-type)? | +--:(dynamic) | | +--rw (address-assign)? | | | +--:(number) | | | | +--rw number-of-dynamic-address? uint16 | | | +--:(explicit) | | | +--rw customer-addresses | | | +--rw address-pool* [pool-id] | | | +--rw pool-id string | | | +--rw start-address | | | | inet:ipv6-address | | | +--rw end-address? | | | inet:ipv6-address | | +--rw (provider-dhcp)? | | | +--:(dhcp-service-type) | | | | +--rw dhcp-service-type? | | | | enumeration | | | +--:(service-type) | | | +--rw (service-type)? | | | +--:(relay) | | | +--rw server-ip-address* | | | inet:ipv6-address | | +--rw (dhcp-relay)? | | +--:(customer-dhcp-servers) | | +--rw customer-dhcp-servers | | +--rw server-ip-address* | | inet:ipv6-address | +--:(static-addresses) | +--rw primary-address? | | -> ../address/address-id | +--rw address* [address-id] | +--rw address-id string | +--rw customer-address? inet:ipv6-address +--rw routing-protocols | ... +--rw oam | ... +--rw security ... ]]>

Routing The routing tree structure is shown in .

Rotuing Tree Structure /nw:networks/network/ac-profile/name +--rw description? string +--rw l2-connection | ... +--rw ip-connection | ... +--rw routing-protocols | +--rw routing-protocol* [id] | +--rw id string | +--rw type? identityref | +--rw routing-profiles* [id] | | +--rw id leafref | | +--rw type? identityref | +--rw static | | +--rw cascaded-lan-prefixes | | +--rw ipv4-lan-prefixes* [lan next-hop] | | | {vpn-common:ipv4}? | | | +--rw lan inet:ipv4-prefix | | | +--rw lan-tag? string | | | +--rw next-hop union | | | +--rw metric? uint32 | | | +--rw bfd-enable? boolean {vpn-common:bfd}? | | | +--rw preference? uint32 | | | +--rw status | | | +--rw admin-status | | | | +--rw status? identityref | | | | +--rw last-change? yang:date-and-time | | | +--ro oper-status | | | +--ro status? identityref | | | +--ro last-change? yang:date-and-time | | +--rw ipv6-lan-prefixes* [lan next-hop] | | {vpn-common:ipv6}? | | +--rw lan inet:ipv4-prefix | | +--rw lan-tag? string | | +--rw next-hop union | | +--rw metric? uint32 | | +--rw bfd-enable? boolean {vpn-common:bfd}? | | +--rw preference? uint32 | | +--rw status | | +--rw admin-status | | | +--rw status? identityref | | | +--rw last-change? yang:date-and-time | | +--ro oper-status | | +--ro status? identityref | | +--ro last-change? yang:date-and-time | +--rw bgp | | +--rw peer-groups | | | +--rw peer-group* [name] | | | +--rw name string | | | +--rw local-address? union | | | +--rw description? string | | | +--rw local-as? inet:as-number | | | +--rw peer-as inet:as-number | | | +--rw address-family? identityref | | | +--rw multihop? uint8 | | | +--rw as-override? boolean | | | +--rw allow-own-as? uint8 | | | +--rw prepend-global-as? boolean | | | +--rw send-default-route? boolean | | | +--rw site-of-origin? | | | | rt-types:route-origin | | | +--rw ipv6-site-of-origin? | | | | rt-types:ipv6-route-origin | | | +--rw redistribute-connected* [address-family] | | | | +--rw address-family identityref | | | | +--rw enable? boolean | | | +--rw bgp-max-prefix | | | | +--rw max-prefix? uint32 | | | | +--rw warning-threshold? decimal64 | | | | +--rw violate-action? enumeration | | | | +--rw restart-timer? uint32 | | | +--rw bgp-timers | | | | +--rw keepalive? uint16 | | | | +--rw hold-time? uint16 | | | +--rw authentication | | | +--rw enable? boolean | | | +--rw keying-material | | | +--rw (option)? | | | +--:(ao) | | | | +--rw enable-ao? boolean | | | | +--rw ao-keychain? | | | | key-chain:key-chain-ref | | | +--:(md5) | | | | +--rw md5-keychain? | | | | key-chain:key-chain-ref | | | +--:(explicit) | | | +--rw key-id? uint32 | | | +--rw key? string | | | +--rw crypto-algorithm? | | | identityref | | +--rw neighbor* [remote-address] | | +--rw remote-address inet:ip-address | | +--rw local-address? union | | +--rw peer-group? | | | -> ../../peer-groups/peer-group/name | | +--rw description? string | | +--rw local-as? inet:as-number | | +--rw peer-as inet:as-number | | +--rw address-family? identityref | | +--rw multihop? uint8 | | +--rw as-override? boolean | | +--rw allow-own-as? uint8 | | +--rw prepend-global-as? boolean | | +--rw send-default-route? boolean | | +--rw site-of-origin? | | | rt-types:route-origin | | +--rw ipv6-site-of-origin? | | | rt-types:ipv6-route-origin | | +--rw redistribute-connected* [address-family] | | | +--rw address-family identityref | | | +--rw enable? boolean | | +--rw bgp-max-prefix | | | +--rw max-prefix? uint32 | | | +--rw warning-threshold? decimal64 | | | +--rw violate-action? enumeration | | | +--rw restart-timer? uint32 | | +--rw bgp-timers | | | +--rw keepalive? uint16 | | | +--rw hold-time? uint16 | | +--rw authentication | | | +--rw enable? boolean | | | +--rw keying-material | | | +--rw (option)? | | | +--:(ao) | | | | +--rw enable-ao? boolean | | | | +--rw ao-keychain? | | | | key-chain:key-chain-ref | | | +--:(md5) | | | | +--rw md5-keychain? | | | | key-chain:key-chain-ref | | | +--:(explicit) | | | +--rw key-id? uint32 | | | +--rw key? string | | | +--rw crypto-algorithm? identityref | | +--rw status | | +--rw admin-status | | | +--rw status? identityref | | | +--rw last-change? yang:date-and-time | | +--ro oper-status | | +--ro status? identityref | | +--ro last-change? yang:date-and-time | +--rw ospf | | +--rw address-family? identityref | | +--rw area-id yang:dotted-quad | | +--rw metric? uint16 | | +--rw sham-links {vpn-common:rtg-ospf-sham-link}? | | | +--rw sham-link* [target-site] | | | +--rw target-site string | | | +--rw metric? uint16 | | +--rw max-lsa? uint32 | | +--rw authentication | | | +--rw enable? boolean | | | +--rw keying-material | | | +--rw (option)? | | | +--:(auth-key-chain) | | | | +--rw key-chain? | | | | key-chain:key-chain-ref | | | +--:(auth-key-explicit) | | | +--rw key-id? uint32 | | | +--rw key? string | | | +--rw crypto-algorithm? identityref | | +--rw status | | +--rw admin-status | | | +--rw status? identityref | | | +--rw last-change? yang:date-and-time | | +--ro oper-status | | +--ro status? identityref | | +--ro last-change? yang:date-and-time | +--rw isis | | +--rw address-family? identityref | | +--rw area-address area-address | | +--rw level? identityref | | +--rw metric? uint16 | | +--rw mode? enumeration | | +--rw authentication | | | +--rw enable? boolean | | | +--rw keying-material | | | +--rw (option)? | | | +--:(auth-key-chain) | | | | +--rw key-chain? | | | | key-chain:key-chain-ref | | | +--:(auth-key-explicit) | | | +--rw key-id? uint32 | | | +--rw key? string | | | +--rw crypto-algorithm? identityref | | +--rw status | | +--rw admin-status | | | +--rw status? identityref | | | +--rw last-change? yang:date-and-time | | +--ro oper-status | | +--ro status? identityref | | +--ro last-change? yang:date-and-time | +--rw rip | | +--rw address-family? identityref | | +--rw timers | | | +--rw update-interval? uint16 | | | +--rw invalid-interval? uint16 | | | +--rw holddown-interval? uint16 | | | +--rw flush-interval? uint16 | | +--rw default-metric? uint8 | | +--rw authentication | | | +--rw enable? boolean | | | +--rw keying-material | | | +--rw (option)? | | | +--:(auth-key-chain) | | | | +--rw key-chain? | | | | key-chain:key-chain-ref | | | +--:(auth-key-explicit) | | | +--rw key? string | | | +--rw crypto-algorithm? identityref | | +--rw status | | +--rw admin-status | | | +--rw status? identityref | | | +--rw last-change? yang:date-and-time | | +--ro oper-status | | +--ro status? identityref | | +--ro last-change? yang:date-and-time | +--rw vrrp | +--rw address-family? identityref | +--rw vrrp-group? uint8 | +--rw backup-peer? inet:ip-address | +--rw virtual-ip-address* inet:ip-address | +--rw priority? uint8 | +--rw ping-reply? boolean | +--rw status | +--rw admin-status | | +--rw status? identityref | | +--rw last-change? yang:date-and-time | +--ro oper-status | +--ro status? identityref | +--ro last-change? yang:date-and-time +--rw oam | ... +--rw security ... ]]>

OAM The OAM tree structure is shown in .

OAM Tree Structure /nw:networks/network/ac-profile/name +--rw description? string +--rw l2-connection | ... +--rw ip-connection | ... +--rw routing-protocols | ... +--rw oam | +--rw bfd | +--rw profile? ac-svc:bfd-profile-reference | +--rw session-type? identityref | +--rw desired-min-tx-interval? uint32 | +--rw required-min-rx-interval? uint32 | +--rw local-multiplier? uint8 | +--rw holdtime? uint32 | +--rw authentication! | | +--rw key-chain? key-chain:key-chain-ref | | +--rw meticulous? boolean | +--rw status | +--rw admin-status | | +--rw status? identityref | | +--rw last-change? yang:date-and-time | +--ro oper-status | +--ro status? identityref | +--ro last-change? yang:date-and-time +--rw security ... ]]>

Security The security tree structure is shown in .

Security Tree Structure /nw:networks/network/ac-profile/name +--rw description? string +--rw l2-connection | ... +--rw ip-connection | ... +--rw routing-protocols | ... +--rw oam | ... +--rw security +--rw encryption {vpn-common:encryption}? | +--rw enabled? boolean | +--rw layer? enumeration +--rw encryption-profile +--rw (profile)? +--:(provider-profile) | +--rw profile-name? leafref +--:(customer-profile) +--rw customer-key-chain? key-chain:key-chain-ref ]]>

YANG Module This module uses types defined in , , , , , and IEEE Std 802.1Qcp. WG List: Editor: Mohamed Boucadair Author: Richard Roberts "; description "This YANG module defines a generic YANG model for the configuration of attachment circuits. Copyright (c) 2023 IETF Trust and the persons identified as authors of the code. All rights reserved. Redistribution and use in source and binary forms, with or without modification, is permitted pursuant to, and subject to the license terms contained in, the Revised BSD License set forth in Section 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info). This version of this YANG module is part of RFC xxx; see the RFC itself for full legal notices."; revision 2022-11-30 { description "Initial revision."; reference "RFC xxxx: A YANG Network Data Model for Attachment Circuits"; } // L2 conenction grouping l2-connection { description "Defines Layer 2 protocols and parameters that are required to enable AC connectivity."; container encapsulation { description "Container for Layer 2 encapsulation."; leaf encap-type { type identityref { base vpn-common:encapsulation-type; } default "vpn-common:priority-tagged"; description "Tagged interface type. By default, the type of the tagged interface is 'priority-tagged'."; } container dot1q { when "derived-from-or-self(../encap-type, " + "'vpn-common:dot1q')" { description "Only applies when the type of the tagged interface is 'dot1q'."; } description "Tagged interface."; uses ac-common:dot1q; container tag-operations { description "Sets the tag manipulation policy for this VPN network access. It defines a set of tag manipulations that allow for the insertion, removal, or rewriting of 802.1Q VLAN tags. These operations are indicated for the CE-PE direction. By default, tag operations are symmetric. As such, the reverse tag operation is assumed on the PE-CE direction."; choice op-choice { description "Selects the tag rewriting policy for a VPN network access."; leaf pop { type empty; description "Pop the outer tag."; } leaf push { type empty; description "Pushes one or two tags defined by the tag-1 and tag-2 leaves. It is assumed that, absent any policy, the default value of 0 will be used for the PCP setting."; } leaf translate { type empty; description "Translates the outer tag to one or two tags. PCP bits are preserved."; } } leaf tag-1 { when 'not(../pop)'; type dot1q-types:vlanid; description "A first tag to be used for push or translate operations. This tag will be used as the outermost tag as a result of the tag operation."; } leaf tag-1-type { type dot1q-types:dot1q-tag-type; default "dot1q-types:s-vlan"; description "Specifies a specific 802.1Q tag type of tag-1."; } leaf tag-2 { when '(../translate)'; type dot1q-types:vlanid; description "A second tag to be used for translation."; } leaf tag-2-type { type dot1q-types:dot1q-tag-type; default "dot1q-types:c-vlan"; description "Specifies a specific 802.1Q tag type of tag-2."; } } } container priority-tagged { when "derived-from-or-self(../encap-type, " + "'vpn-common:priority-tagged')" { description "Only applies when the type of the tagged interface is 'priority-tagged'."; } description "Priority tagged container."; uses ac-common:priority-tagged; } container qinq { when "derived-from-or-self(../encap-type, " + "'vpn-common:qinq')" { description "Only applies when the type of the tagged interface is 'QinQ'."; } description "Includes QinQ parameters."; uses ac-common:qinq; container tag-operations { description "Sets the tag manipulation policy for this VPN network access. It defines a set of tag manipulations that allow for the insertion, removal, or rewriting of 802.1Q VLAN tags. These operations are indicated for the CE-PE direction. By default, tag operations are symmetric. As such, the reverse tag operation is assumed on the PE-CE direction."; choice op-choice { description "Selects the tag rewriting policy for a VPN network access."; leaf pop { type uint8 { range "1|2"; } description "Pops one or two tags as a function of the indicated pop value."; } leaf push { type empty; description "Pushes one or two tags defined by the tag-1 and tag-2 leaves. It is assumed that, absent any policy, the default value of 0 will be used for PCP setting."; } leaf translate { type uint8 { range "1|2"; } description "Translates one or two outer tags. PCP bits are preserved. The following operations are supported: - translate 1 with tag-1 leaf is provided: only the outermost tag is translated to the value in tag-1. - translate 2 with both tag-1 and tag-2 leaves are provided: both outer and inner tags are translated to the values in tag-1 and tag-2, respectively. - translate 2 with tag-1 leaf is provided: the outer tag is popped while the inner tag is translated to the value in tag-1."; } } leaf tag-1 { when 'not(../pop)'; type dot1q-types:vlanid; description "A first tag to be used for push or translate operations. This tag will be used as the outermost tag as a result of the tag operation."; } leaf tag-1-type { type dot1q-types:dot1q-tag-type; default "dot1q-types:s-vlan"; description "Specifies a specific 802.1Q tag type of tag-1."; } leaf tag-2 { when 'not(../pop)'; type dot1q-types:vlanid; description "A second tag to be used for push or translate operations."; } leaf tag-2-type { type dot1q-types:dot1q-tag-type; default "dot1q-types:c-vlan"; description "Specifies a specific 802.1Q tag type of tag-2."; } } } } choice l2-service { description "The Layer 2 connectivity service can be provided by indicating a pointer to an L2VPN or by specifying a Layer 2 tunnel service."; container l2-tunnel-service { description "Defines a Layer 2 tunnel termination. It is only applicable when a tunnel is required. The supported values are 'pseudowire', 'vpls', and 'vxlan'. Other values may be defined, if needed."; uses ac-common:l2-tunnel-service; } case l2vpn { leaf l2vpn-id { type vpn-common:vpn-id; description "Indicates the L2VPN service associated with an Integrated Routing and Bridging (IRB) interface."; } } } } grouping l2-connection-if-ref { description "Defines Layer 2 protocols and parameters that are required to enable AC connectivity."; uses l2-connection; leaf l2-termination-point { type string; description "Specifies a reference to a local Layer 2 termination point, such as a Layer 2 sub-interface."; } leaf local-bridge-reference { type string; description "Specifies a local bridge reference to accommodate, for example, implementations that require internal bridging. A reference may be a local bridge domain."; } leaf bearer-reference { if-feature "vpn-common:bearer-reference"; type string; description "This is an internal reference for the service provider to identify the bearer associated with this VPN."; } container lag-interface { if-feature "vpn-common:lag-interface"; description "Container for configuration of Link Aggregation Group (LAG) interface attributes."; leaf lag-interface-id { type string; description "LAG interface identifier."; } container member-link-list { description "Container for the member link list."; list member-link { key "name"; description "Member link."; leaf name { type string; description "Member link name."; } } } } } grouping ip-connection { description "Defines IP connection parameters."; leaf l3-termination-point { type string; description "Specifies a reference to a local Layer 3 termination point, such as a bridge domain interface."; } container ipv4 { if-feature "vpn-common:ipv4"; description "IPv4-specific parameters."; leaf local-address { type inet:ipv4-address; description "The IP address used at the provider's interface."; } uses ac-common:ipv4-allocation-type; choice allocation-type { description "Choice of the IPv4 address allocation."; case dynamic { description "When the addresses are allocated by DHCP or other dynamic means local to the infrastructure."; choice address-assign { default "number"; description "A choice for how IPv4 addresses are assigned."; case number { leaf number-of-dynamic-address { type uint16; default "1"; description "Specifies the number of IP addresses to be assigned to the customer on this access."; } } case explicit { container customer-addresses { description "Container for customer addresses to be allocated using DHCP."; list address-pool { key "pool-id"; description "Describes IP addresses to be dyncamically allocated. When only 'start-address' is present, it represents a single address. When both 'start-address' and 'end-address' are specified, it implies a range inclusive of both addresses."; leaf pool-id { type string; description "A pool identifier for the address range from 'start-address' to 'end-address'."; } leaf start-address { type inet:ipv6-address; mandatory true; description "Indicates the first address in the pool."; } leaf end-address { type inet:ipv6-address; description "Indicates the last address in the pool."; } } } } } choice provider-dhcp { description "Parameters related to DHCP-allocated addresses. IP addresses are allocated by DHCP, which is provided by the operator."; leaf dhcp-service-type { type enumeration { enum server { description "Local DHCP server."; } enum relay { description "Local DHCP relay. DHCP requests are relayed to a provider's server."; } } description "Indicates the type of DHCP service to be enabled on this access."; } choice service-type { description "Choice based on the DHCP service type."; case relay { description "Container for a list of the provider's DHCP servers (i.e., 'dhcp-service-type' is set to 'relay')."; leaf-list server-ip-address { type inet:ipv6-address; description "IPv6 addresses of the provider's DHCP server, for use by the local DHCP relay."; } } } } choice dhcp-relay { description "The DHCP relay is provided by the operator."; container customer-dhcp-servers { description "Container for a list of the customer's DHCP servers."; leaf-list server-ip-address { type inet:ipv6-address; description "IPv6 addresses of the customer's DHCP server."; } } } } case static-addresses { description "Lists the IPv6 addresses that are used."; leaf primary-address { type leafref { path "../address/address-id"; } description "Primary IP address of the connection."; } list address { key "address-id"; description "Lists the IPv6 addresses that are used."; leaf address-id { type string; description "An identifier of the static IPv6 address."; } leaf customer-address { type inet:ipv6-address; description "An IPv6 address of the customer side."; } } } } } container ipv6 { if-feature "vpn-common:ipv6"; description "IPv6-specific parameters."; leaf local-address { type inet:ipv6-address; description "IPv6 address of the provider side."; } uses ac-common:ipv6-allocation-type; choice allocation-type { description "Choice of the IPv6 address allocation."; case dynamic { description "When the addresses are allocated by DHCP or other dynamic means local to the infrastructure."; choice address-assign { default "number"; description "A choice for how IPv6 addresses are assigned."; case number { leaf number-of-dynamic-address { type uint16; default "1"; description "Specifies the number of IP addresses to be assigned to the customer on this access."; } } case explicit { container customer-addresses { description "Container for customer addresses to be allocated using DHCP."; list address-pool { key "pool-id"; description "Describes IP addresses to be dyncamically allocated. When only 'start-address' is present, it represents a single address. When both 'start-address' and 'end-address' are specified, it implies a range inclusive of both addresses."; leaf pool-id { type string; description "A pool identifier for the address range from 'start-address' to 'end-address'."; } leaf start-address { type inet:ipv6-address; mandatory true; description "Indicates the first address in the pool."; } leaf end-address { type inet:ipv6-address; description "Indicates the last address in the pool."; } } } } } choice provider-dhcp { description "Parameters related to DHCP-allocated addresses. IP addresses are allocated by DHCP, which is provided by the operator."; leaf dhcp-service-type { type enumeration { enum server { description "Local DHCP server."; } enum relay { description "Local DHCP relay. DHCP requests are relayed to a provider's server."; } } description "Indicates the type of DHCP service to be enabled on this access."; } choice service-type { description "Choice based on the DHCP service type."; case relay { description "Container for a list of the provider's DHCP servers (i.e., 'dhcp-service-type' is set to 'relay')."; leaf-list server-ip-address { type inet:ipv6-address; description "IPv6 addresses of the provider's DHCP server, for use by the local DHCP relay."; } } } } choice dhcp-relay { description "The DHCP relay is provided by the operator."; container customer-dhcp-servers { description "Container for a list of the customer's DHCP servers."; leaf-list server-ip-address { type inet:ipv6-address; description "IPv6 addresses of the customer's DHCP server."; } } } } case static-addresses { description "Lists the IPv6 addresses that are used."; leaf primary-address { type leafref { path "../address/address-id"; } description "Primary IP address of the connection."; } list address { key "address-id"; description "Lists the IPv6 addresses that are used."; leaf address-id { type string; description "An identifier of the static IPv6 address."; } leaf customer-address { type inet:ipv6-address; description "An IPv6 address of the customer side."; } } } } } } /* Routing */ //BGP-generic //BGP-extended grouping bgp-base { description "Configuration specific to BGP."; leaf description { type string; description "Includes a description of the BGP session. This description is meant to be used for diagnostic purposes. The semantic of the description is local to an implementation."; } leaf local-as { type inet:as-number; description "Indicates a local AS Number (ASN), if an ASN distinct from the ASN configured at the VPN node level is needed."; } leaf peer-as { type inet:as-number; mandatory true; description "Indicates the customer's ASN when the customer requests BGP routing."; } leaf address-family { type identityref { base vpn-common:address-family; } description "This node contains the address families to be activated. 'dual-stack' means that both IPv4 and IPv6 will be activated."; } leaf multihop { type uint8; description "Describes the number of IP hops allowed between a given BGP neighbor and the PE."; } leaf as-override { type boolean; default "false"; description "Defines whether ASN override is enabled, i.e., replacing the ASN of the customer specified in the AS_PATH attribute with the local ASN."; } leaf allow-own-as { type uint8; default "0"; description "If set, specifies the maximum number of occurrences of the provider's ASN that are permitted within the AS_PATH before it is rejected."; } leaf prepend-global-as { type boolean; default "false"; description "In some situations, the ASN that is provided at the VPN node level may be distinct from the ASN configured at the VPN network access level. When such ASNs are provided, they are both prepended to the BGP route updates for this access. To disable that behavior, 'prepend-global-as' must be set to 'false'. In such a case, the ASN that is provided at the VPN node level is not prepended to the BGP route updates for this access."; } leaf send-default-route { type boolean; default "false"; description "Defines whether default routes can be advertised to a peer. If set, the default routes are advertised to a peer."; } leaf site-of-origin { when "../address-family = 'vpn-common:ipv4' " + "or 'vpn-common:dual-stack'" { description "Only applies if IPv4 is activated."; } type rt-types:route-origin; description "The Site of Origin attribute is encoded as a Route Origin Extended Community. It is meant to uniquely identify the set of routes learned from a site via a particular CE-PE connection and is used to prevent routing loops."; reference "RFC 4364: BGP/MPLS IP Virtual Private Networks (VPNs), Section 7"; } leaf ipv6-site-of-origin { when "../address-family = 'vpn-common:ipv6' " + "or 'vpn-common:dual-stack'" { description "Only applies if IPv6 is activated."; } type rt-types:ipv6-route-origin; description "The IPv6 Site of Origin attribute is encoded as an IPv6 Route Origin Extended Community. It is meant to uniquely identify the set of routes learned from a site via VRF information."; reference "RFC 5701: IPv6 Address Specific BGP Extended Community Attribute"; } list redistribute-connected { key "address-family"; description "Indicates, per address family, the policy to follow for connected routes."; leaf address-family { type identityref { base vpn-common:address-family; } description "Indicates the address family."; } leaf enable { type boolean; description "Enables the redistribution of connected routes."; } } container bgp-max-prefix { description "Controls the behavior when a prefix maximum is reached."; leaf max-prefix { type uint32; default "5000"; description "Indicates the maximum number of BGP prefixes allowed in the BGP session. It allows control of how many prefixes can be received from a neighbor. If the limit is exceeded, the action indicated in 'violate-action' will be followed."; reference "RFC 4271: A Border Gateway Protocol 4 (BGP-4), Section 8.2.2"; } leaf warning-threshold { type decimal64 { fraction-digits 5; range "0..100"; } units "percent"; default "75"; description "When this value is reached, a warning notification will be triggered."; } leaf violate-action { type enumeration { enum warning { description "Only a warning message is sent to the peer when the limit is exceeded."; } enum discard-extra-paths { description "Discards extra paths when the limit is exceeded."; } enum restart { description "The BGP session restarts after the indicated time interval."; } } description "If the BGP neighbor 'max-prefix' limit is reached, the action indicated in 'violate-action' will be followed."; } leaf restart-timer { type uint32; units "seconds"; description "Time interval after which the BGP session will be reestablished."; } } container bgp-timers { description "Includes two BGP timers that can be customized when building a VPN service with BGP used as the CE-PE routing protocol."; leaf keepalive { type uint16 { range "0..21845"; } units "seconds"; default "30"; description "This timer indicates the KEEPALIVE messages' frequency between a PE and a BGP peer. If set to '0', it indicates that KEEPALIVE messages are disabled. It is suggested that the maximum time between KEEPALIVE messages be one-third of the Hold Time interval."; reference "RFC 4271: A Border Gateway Protocol 4 (BGP-4), Section 4.4"; } leaf hold-time { type uint16 { range "0 | 3..65535"; } units "seconds"; default "90"; description "Indicates the maximum number of seconds that may elapse between the receipt of successive KEEPALIVE and/or UPDATE messages from the peer. The Hold Time must be either zero or at least three seconds."; reference "RFC 4271: A Border Gateway Protocol 4 (BGP-4), Section 4.2"; } } } grouping bgp-base-with-auth { description "Configuration specific to BGP."; uses bgp-base; uses ac-common:bgp-authentication; } //routing profile grouping routing-profile { description "Defines routing protocols."; list routing-protocol { key "id"; description "List of routing protocols used on the CE-PE link. This list can be augmented."; leaf id { type string; description "Unique identifier for the routing protocol."; } leaf type { type identityref { base vpn-common:routing-protocol-type; } description "Type of routing protocol."; } container bgp { when "derived-from-or-self(../type, " + "'vpn-common:bgp-routing')" { description "Only applies when the protocol is BGP."; } description "Configuration specific to BGP."; uses bgp-base; } container ospf { when "derived-from-or-self(../type, " + "'vpn-common:ospf-routing')" { description "Only applies when the protocol is OSPF."; } description "Configuration specific to OSPF."; uses ac-common:ospf-basic; leaf max-lsa { type uint32 { range "1..4294967294"; } description "Maximum number of allowed Link State Advertisements (LSAs) that the OSPF instance will accept."; } } container isis { when "derived-from-or-self(../type, " + "'vpn-common:isis-routing')" { description "Only applies when the protocol is IS-IS."; } description "Configuration specific to IS-IS."; uses ac-common:isis-basic; leaf level { type identityref { base vpn-common:isis-level; } description "Can be 'level-1', 'level-2', or 'level-1-2'."; reference "RFC 9181: A Common YANG Data Model for Layer 2 and Layer 3 VPNs"; } leaf metric { type uint16; default "1"; description "Metric of the PE-CE link. It is used in the routing state calculation and path selection."; } leaf mode { type enumeration { enum active { description "The interface sends or receives IS-IS protocol control packets."; } enum passive { description "Suppresses the sending of IS-IS updates through the specified interface."; } } default "active"; description "IS-IS interface mode type."; } } container rip { when "derived-from-or-self(../type, " + "'vpn-common:rip-routing')" { description "Only applies when the protocol is RIP. For IPv4, the model assumes that RIP version 2 is used."; } description "Configuration specific to RIP routing."; leaf address-family { type identityref { base vpn-common:address-family; } description "Indicates whether IPv4, IPv6, or both address families are to be activated."; } container timers { description "Indicates the RIP timers."; reference "RFC 2453: RIP Version 2"; leaf update-interval { type uint16 { range "1..32767"; } units "seconds"; default "30"; description "Indicates the RIP update time, i.e., the amount of time for which RIP updates are sent."; } leaf invalid-interval { type uint16 { range "1..32767"; } units "seconds"; default "180"; description "The interval before a route is declared invalid after no updates are received. This value is at least three times the value for the 'update-interval' argument."; } leaf holddown-interval { type uint16 { range "1..32767"; } units "seconds"; default "180"; description "Specifies the interval before better routes are released."; } leaf flush-interval { type uint16 { range "1..32767"; } units "seconds"; default "240"; description "Indicates the RIP flush timer, i.e., the amount of time that must elapse before a route is removed from the routing table."; } } leaf default-metric { type uint8 { range "0..16"; } default "1"; description "Sets the default metric."; } } container vrrp { when "derived-from-or-self(../type, " + "'vpn-common:vrrp-routing')" { description "Only applies when the protocol is the Virtual Router Redundancy Protocol (VRRP)."; } description "Configuration specific to VRRP."; reference "RFC 5798: Virtual Router Redundancy Protocol (VRRP) Version 3 for IPv4 and IPv6"; leaf address-family { type identityref { base vpn-common:address-family; } description "Indicates whether IPv4, IPv6, or both address families are to be enabled."; } leaf ping-reply { type boolean; default "false"; description "Controls whether the VRRP speaker should reply to ping requests."; } } } } grouping routing { description "Defines routing protocols."; list routing-protocol { key "id"; description "List of routing protocols used on the CE-PE link. This list can be augmented."; leaf id { type string; description "Unique identifier for the routing protocol."; } leaf type { type identityref { base vpn-common:routing-protocol-type; } description "Type of routing protocol."; } list routing-profiles { key "id"; description "Routing profiles."; leaf id { type leafref { path "/nw:networks/nw:network" + "/ac-ntw:specific-provisioning-profiles/valid-provider-identifiers" + "/routing-profile-identifier/id"; } //type ac-svc:routing-profile-reference; description "Routing profile to be used."; } leaf type { type identityref { base vpn-common:ie-type; } description "Import, export, or both."; } } container static { when "derived-from-or-self(../type, " + "'vpn-common:static-routing')" { description "Only applies when the protocol is a static routing protocol."; } description "Configuration specific to static routing."; container cascaded-lan-prefixes { description "LAN prefixes from the customer."; list ipv4-lan-prefixes { if-feature "vpn-common:ipv4"; key "lan next-hop"; description "List of LAN prefixes for the site."; uses ac-common:ipv4-static-rtg-entry; leaf bfd-enable { if-feature "vpn-common:bfd"; type boolean; description "Enables Bidirectional Forwarding Detection (BFD)."; } leaf preference { type uint32; description "Indicates the preference associated with the static route."; } uses vpn-common:service-status; } list ipv6-lan-prefixes { if-feature "vpn-common:ipv6"; key "lan next-hop"; description "List of LAN prefixes for the site."; uses ac-common:ipv4-static-rtg-entry; leaf bfd-enable { if-feature "vpn-common:bfd"; type boolean; description "Enables BFD."; } leaf preference { type uint32; description "Indicates the preference associated with the static route."; } uses vpn-common:service-status; } } } container bgp { when "derived-from-or-self(../type, " + "'vpn-common:bgp-routing')" { description "Only applies when the protocol is BGP."; } description "Configuration specific to BGP."; container peer-groups { description "Configuration for BGP peer-groups"; list peer-group { key "name"; description "List of BGP peer-groups configured on the local system - uniquely identified by peer-group name"; leaf name { type string; description "Name of the BGP peer-group"; } leaf local-address { type union { type inet:ip-address; type if:interface-ref; } description "Sets the local IP address to use for the BGP transport session. This may be expressed as either an IP address or a reference to an interface."; } uses bgp-base-with-auth; } } list neighbor { key "remote-address"; description "List of BGP neighbors."; leaf remote-address { type inet:ip-address; description "The remote IP address of this entry's BGP peer."; } leaf local-address { type union { type inet:ip-address; type if:interface-ref; } description "Sets the local IP address to use for the BGP transport session. This may be expressed as either an IP address or a reference to an interface."; } leaf peer-group { type leafref { path "../../peer-groups/peer-group/name"; } description "The peer-group with which this neighbor is associated."; } uses bgp-base-with-auth; uses vpn-common:service-status; } } container ospf { when "derived-from-or-self(../type, " + "'vpn-common:ospf-routing')" { description "Only applies when the protocol is OSPF."; } description "Configuration specific to OSPF."; uses ac-common:ospf-basic; container sham-links { if-feature "vpn-common:rtg-ospf-sham-link"; description "List of sham links."; reference "RFC 4577: OSPF as the Provider/Customer Edge Protocol for BGP/MPLS IP Virtual Private Networks (VPNs), Section 4.2.7 RFC 6565: OSPFv3 as a Provider Edge to Customer Edge (PE-CE) Routing Protocol, Section 5"; list sham-link { key "target-site"; description "Creates a sham link with another site."; leaf target-site { type string; description "Target site for the sham link connection. The site is referred to by its identifier."; } leaf metric { type uint16; default "1"; description "Metric of the sham link. It is used in the routing state calculation and path selection. The default value is set to '1'."; reference "RFC 4577: OSPF as the Provider/Customer Edge Protocol for BGP/MPLS IP Virtual Private Networks (VPNs), Section 4.2.7.3 RFC 6565: OSPFv3 as a Provider Edge to Customer Edge (PE-CE) Routing Protocol, Section 5.2"; } } } leaf max-lsa { type uint32 { range "1..4294967294"; } description "Maximum number of allowed Link State Advertisements (LSAs) that the OSPF instance will accept."; } uses ac-common:ospf-authentication; uses vpn-common:service-status; } container isis { when "derived-from-or-self(../type, " + "'vpn-common:isis-routing')" { description "Only applies when the protocol is IS-IS."; } description "Configuration specific to IS-IS."; uses ac-common:isis-basic; leaf level { type identityref { base vpn-common:isis-level; } description "Can be 'level-1', 'level-2', or 'level-1-2'."; reference "RFC 9181: A Common YANG Data Model for Layer 2 and Layer 3 VPNs"; } leaf metric { type uint16; default "1"; description "Metric of the PE-CE link. It is used in the routing state calculation and path selection."; } leaf mode { type enumeration { enum active { description "The interface sends or receives IS-IS protocol control packets."; } enum passive { description "Suppresses the sending of IS-IS updates through the specified interface."; } } default "active"; description "IS-IS interface mode type."; } uses ac-common:isis-authentication; uses vpn-common:service-status; } container rip { when "derived-from-or-self(../type, " + "'vpn-common:rip-routing')" { description "Only applies when the protocol is RIP. For IPv4, the model assumes that RIP version 2 is used."; } description "Configuration specific to RIP routing."; leaf address-family { type identityref { base vpn-common:address-family; } description "Indicates whether IPv4, IPv6, or both address families are to be activated."; } container timers { description "Indicates the RIP timers."; reference "RFC 2453: RIP Version 2"; leaf update-interval { type uint16 { range "1..32767"; } units "seconds"; default "30"; description "Indicates the RIP update time, i.e., the amount of time for which RIP updates are sent."; } leaf invalid-interval { type uint16 { range "1..32767"; } units "seconds"; default "180"; description "The interval before a route is declared invalid after no updates are received. This value is at least three times the value for the 'update-interval' argument."; } leaf holddown-interval { type uint16 { range "1..32767"; } units "seconds"; default "180"; description "Specifies the interval before better routes are released."; } leaf flush-interval { type uint16 { range "1..32767"; } units "seconds"; default "240"; description "Indicates the RIP flush timer, i.e., the amount of time that must elapse before a route is removed from the routing table."; } } leaf default-metric { type uint8 { range "0..16"; } default "1"; description "Sets the default metric."; } uses ac-common:rip-authentication; uses vpn-common:service-status; } container vrrp { when "derived-from-or-self(../type, " + "'vpn-common:vrrp-routing')" { description "Only applies when the protocol is the Virtual Router Redundancy Protocol (VRRP)."; } description "Configuration specific to VRRP."; reference "RFC 5798: Virtual Router Redundancy Protocol (VRRP) Version 3 for IPv4 and IPv6"; leaf address-family { type identityref { base vpn-common:address-family; } description "Indicates whether IPv4, IPv6, or both address families are to be enabled."; } leaf vrrp-group { type uint8 { range "1..255"; } description "Includes the VRRP group identifier."; } leaf backup-peer { type inet:ip-address; description "Indicates the IP address of the peer."; } leaf-list virtual-ip-address { type inet:ip-address; description "Virtual IP addresses for a single VRRP group."; reference "RFC 5798: Virtual Router Redundancy Protocol (VRRP) Version 3 for IPv4 and IPv6, Sections 1.2 and 1.3"; } leaf priority { type uint8 { range "1..254"; } default "100"; description "Sets the local priority of the VRRP speaker."; } leaf ping-reply { type boolean; default "false"; description "Controls whether the VRRP speaker should reply to ping requests."; } uses vpn-common:service-status; } } } // OAM grouping bfd { description "Grouping for BFD."; leaf session-type { type identityref { base vpn-common:bfd-session-type; } default "vpn-common:classic-bfd"; description "Specifies the BFD session type."; } leaf desired-min-tx-interval { type uint32; units "microseconds"; default "1000000"; description "The minimum interval between transmissions of BFD Control packets, as desired by the operator."; reference "RFC 5880: Bidirectional Forwarding Detection (BFD), Section 6.8.7"; } leaf required-min-rx-interval { type uint32; units "microseconds"; default "1000000"; description "The minimum interval between received BFD Control packets that the PE should support."; reference "RFC 5880: Bidirectional Forwarding Detection (BFD), Section 6.8.7"; } leaf local-multiplier { type uint8 { range "1..255"; } default "3"; description "Specifies the detection multiplier that is transmitted to a BFD peer. The detection interval for the receiving BFD peer is calculated by multiplying the value of the negotiated transmission interval by the received detection multiplier value."; reference "RFC 5880: Bidirectional Forwarding Detection (BFD), Section 6.8.7"; } leaf holdtime { type uint32; units "milliseconds"; description "Expected BFD holdtime. The customer may impose some fixed values for the holdtime period if the provider allows the customer to use this function. If the provider doesn't allow the customer to use this function, fixed values will not be set."; reference "RFC 5880: Bidirectional Forwarding Detection (BFD), Section 6.8.18"; } } // AC profile grouping ac-profile { description "Grouping for attachment circuit profiles."; // Layer 2 container l2-connection { description "Defines Layer 2 protocols and parameters that are required to enable AC connectivity."; //uses l2-connection; } // Layer 3 container ip-connection { description "Defines IP connection parameters."; } // Routing container routing-protocols { description "Defines routing protocols."; uses routing-profile; } // OAM container oam { description "Defines the Operations, Administration, and Maintenance (OAM) mechanisms used."; container bfd { if-feature "vpn-common:bfd"; description "Container for BFD."; uses bfd; } } } //AC network provisioning grouping ac { description "Grouping for attachment circuits."; leaf description { type string; description "Associates a description with an AC."; } // Layer 2 container l2-connection { description "Defines Layer 2 protocols and parameters that are required to enable AC connectivity."; uses l2-connection-if-ref; } // Layer 3 container ip-connection { description "Defines IP connection parameters."; uses ip-connection; } // Routing container routing-protocols { description "Defines routing protocols."; uses routing; } // OAM container oam { description "Defines the Operations, Administration, and Maintenance (OAM) mechanisms used."; container bfd { description "Container for BFD."; leaf profile { type leafref { path "/nw:networks/nw:network" + "/ac-ntw:specific-provisioning-profiles" + "/valid-provider-identifiers" + "/bfd-profile-identifier/id"; } //type ac-svc:bfd-profile-reference; description "Well-known service provider profile name. The provider can propose some profiles to the customer, depending on the service level the customer wants to achieve."; } uses bfd; container authentication { presence "Enables BFD authentication"; description "Parameters for BFD authentication."; leaf key-chain { type key-chain:key-chain-ref; description "Name of the key chain."; } leaf meticulous { type boolean; description "Enables meticulous mode."; reference "RFC 5880: Bidirectional Forwarding Detection (BFD), Section 6.7"; } } uses vpn-common:service-status; } } // Security container security { description "Site-specific security parameters."; container encryption { if-feature "vpn-common:encryption"; description "Container for AC security encryption."; leaf enabled { type boolean; default "false"; description "If set to 'true', traffic encryption on the connection is required. Otherwise, it is disabled."; } leaf layer { when "../enabled = 'true'" { description "Included only when encryption is enabled."; } type enumeration { enum layer2 { description "Encryption occurs at Layer 2."; } enum layer3 { description "Encryption occurs at Layer 3. For example, IPsec may be used when a customer requests Layer 3 encryption."; } } description "Indicates the layer on which encryption is applied."; } } container encryption-profile { when "../encryption/enabled = 'true'" { description "Indicates the layer on which encryption is enabled."; } description "Container for the encryption profile."; choice profile { description "Choice for the encryption profile."; case provider-profile { leaf profile-name { type leafref { path "/nw:networks/nw:network" + "/ac-ntw:specific-provisioning-profiles" + "/valid-provider-identifiers" + "/encryption-profile-identifier/id"; } //type ac-svc:encryption-profile-reference; description "Name of the service provider's profile to be applied."; } } case customer-profile { leaf customer-key-chain { type key-chain:key-chain-ref; description "Customer-supplied key chain."; } } } } } } augment "/nw:networks/nw:network" { description "Add a list of profiles."; // References to the profiles defined in the AC-SVC container specific-provisioning-profiles { description "Contains a set of valid profiles to reference in the AC activation."; uses vpn-common:vpn-profile-cfg; } list ac-profile { key "name"; description "Maintains a list of AC profiles."; leaf name { type string; description "Name of the AC."; } uses ac-ntw:ac-profile; } } augment "/nw:networks/nw:network/nw:node" + "/sap:service/sap:sap" { when '../../../nw:network-types/sap:sap-network' { description "Augmentation parameters apply only for SAP networks."; } description "Augments SAPs with AC provisioning details."; list ac { key "name"; description "List of ACs."; leaf name { type string; description "A local AC identifier."; } leaf ac-ref { type ac-svc:attachment-circuit-reference; description "A reference to the AC as exposed at the service level."; } list ac-profile { key "profile-id"; description "List of AC profiles."; leaf profile-id { type leafref { path "/nw:networks/nw:network/ac-profile/name"; } description "A reference to an AC profile."; } } uses ac-ntw:ac; } } } ]]>

Security Considerations The YANG module specified in this document defines a schema for data that is designed to be accessed via network management protocols such as NETCONF or RESTCONF . The lowest NETCONF layer is the secure transport layer, and the mandatory-to-implement secure transport is Secure Shell (SSH) . The lowest RESTCONF layer is HTTPS, and the mandatory-to-implement secure transport is TLS . The Network Configuration Access Control Model (NACM) provides the means to restrict access for particular NETCONF or RESTCONF users to a preconfigured subset of all available NETCONF or RESTCONF protocol operations and content. There are a number of data nodes defined in this YANG module that are writable/creatable/deletable (i.e., config true, which is the default). These data nodes may be considered sensitive or vulnerable in some network environments. Write operations (e.g., edit-config) and delete operations to these data nodes without proper protection or authentication can have a negative effect on network operations. These are the subtrees and data nodes and their sensitivity/ vulnerability in the "ietf-ac-ntw" module:

• TBC
• TBC

Some of the readable data nodes in this YANG module may be considered sensitive or vulnerable in some network environments. It is thus important to control read access (e.g., via get, get-config, or notification) to these data nodes. These are the subtrees and data nodes and their sensitivity/vulnerability in the "ietf-ac-svc" module:

• TBC
• TBC

IANA Considerations IANA is requested to register the following URI in the "ns" subregistry within the "IETF XML Registry" : IANA is requested to register the following YANG module in the "YANG Module Names" subregistry within the "YANG Parameters" registry.

References Normative References Orange Juniper Telefonica Nokia Huawei Technologies This document specifies a YANG service data model for Attachment Circuits (ACs). The model can be used for the provisioning of ACs prior or during service provisioning (e.g., Network Slice Service). The document specifies also a module that updates other service and network modules with the required information to bind specific services to ACs that are created using the AC service model. The AC service model is designed with the intent to be reusable. Whether a service model reuses structures defined in the AC service model or simply include an AC reference is a design choice of these service models. Relying upon the AC model to manage ACs over which a service is delivered has the merit to decorrelate the management of a service vs. upgrade the AC components to reflect recent AC technologies or features. Each AC is identified with a unique identifier within a domain. The mapping between this AC and a network node (typically, a Provider Edge (PE)) that terminates an AC is hidden to the application/ customer that makes use of the AC service model. Such an information is internal to the network controller. Thus, the details about the (network node-specific) attachment interfaces are not exposed in this service model. As a complement to the Layer 3 Virtual Private Network Service Model (L3SM), which is used for communication between customers and service providers, this document defines an L3VPN Network Model (L3NM) that can be used for the provisioning of Layer 3 Virtual Private Network (L3VPN) services within a service provider network. The model provides a network-centric view of L3VPN services. The L3NM is meant to be used by a network controller to derive the configuration information that will be sent to relevant network devices. The model can also facilitate communication between a service orchestrator and a network controller/orchestrator. This document defines an L2VPN Network Model (L2NM) that can be used to manage the provisioning of Layer 2 Virtual Private Network (L2VPN) services within a network (e.g., a service provider network). The L2NM complements the L2VPN Service Model (L2SM) by providing a network-centric view of the service that is internal to a service provider. The L2NM is particularly meant to be used by a network controller to derive the configuration information that will be sent to relevant network devices. Also, this document defines a YANG module to manage Ethernet segments and the initial versions of two IANA-maintained modules that include a set of identities of BGP Layer 2 encapsulation types and pseudowire types. Orange Telefonica Nokia Huawei Nokia This document defines a YANG data model for representing an abstract view of the provider network topology that contains the points from which its services can be attached (e.g., basic connectivity, VPN, network slices). Also, the model can be used to retrieve the points where the services are actually being delivered to customers (including peer networks). This document augments the 'ietf-network' data model by adding the concept of Service Attachment Points (SAPs). The SAPs are the network reference points to which network services, such as Layer 3 Virtual Private Network (L3VPN) or Layer 2 Virtual Private Network (L2VPN), can be attached. One or multiple services can be bound to the same SAP. Both User-Network Interface (UNI) and Network-to- Network Interface (NNI) are supported in the SAP data model. Datastores are a fundamental concept binding the data models written in the YANG data modeling language to network management protocols such as the Network Configuration Protocol (NETCONF) and RESTCONF. This document defines an architectural framework for datastores based on the experience gained with the initial simpler model, addressing requirements that were not well supported in the initial model. This document updates RFC 7950. In many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. RFC 2119 specifies common key words that may be used in protocol specifications. This document aims to reduce the ambiguity by clarifying that only UPPERCASE usage of the key words have the defined special meanings. This document introduces a collection of common data types to be used with the YANG data modeling language. This document obsoletes RFC 6021. This document describes the key chain YANG data model. Key chains are commonly used for routing protocol authentication and other applications requiring symmetric keys. A key chain is a list containing one or more elements containing a Key ID, key string, send/accept lifetimes, and the associated authentication or encryption algorithm. By properly overlapping the send and accept lifetimes of multiple key chain elements, key strings and algorithms may be gracefully updated. By representing them in a YANG data model, key distribution can be automated. This document defines a collection of common data types using the YANG data modeling language. These derived common types are designed to be imported by other modules defined in the routing area. This document defines a YANG data model for the management of network interfaces. It is expected that interface-type-specific data models augment the generic interfaces data model defined in this document. The data model includes definitions for configuration and system state (status information and counters for the collection of statistics). The YANG data model in this document conforms to the Network Management Datastore Architecture (NMDA) defined in RFC 8342. This document obsoletes RFC 7223. This document defines a common YANG module that is meant to be reused by various VPN-related modules such as Layer 3 VPN and Layer 2 VPN network models. The Network Configuration Protocol (NETCONF) defined in this document provides mechanisms to install, manipulate, and delete the configuration of network devices. It uses an Extensible Markup Language (XML)-based data encoding for the configuration data as well as the protocol messages. The NETCONF protocol operations are realized as remote procedure calls (RPCs). This document obsoletes RFC 4741. [STANDARDS-TRACK] This document describes an HTTP-based protocol that provides a programmatic interface for accessing data defined in YANG, using the datastore concepts defined in the Network Configuration Protocol (NETCONF). This document describes a method for invoking and running the Network Configuration Protocol (NETCONF) within a Secure Shell (SSH) session as an SSH subsystem. This document obsoletes RFC 4742. [STANDARDS-TRACK] This document specifies version 1.3 of the Transport Layer Security (TLS) protocol. TLS allows client/server applications to communicate over the Internet in a way that is designed to prevent eavesdropping, tampering, and message forgery. This document updates RFCs 5705 and 6066, and obsoletes RFCs 5077, 5246, and 6961. This document also specifies new requirements for TLS 1.2 implementations. The standardization of network configuration interfaces for use with the Network Configuration Protocol (NETCONF) or the RESTCONF protocol requires a structured and secure operating environment that promotes human usability and multi-vendor interoperability. There is a need for standard mechanisms to restrict NETCONF or RESTCONF protocol access for particular users to a preconfigured subset of all available NETCONF or RESTCONF protocol operations and content. This document defines such an access control model. This document obsoletes RFC 6536. This document describes an IANA maintained registry for IETF standards which use Extensible Markup Language (XML) related items such as Namespaces, Document Type Declarations (DTDs), Schemas, and Resource Description Framework (RDF) Schemas. YANG is a data modeling language used to model configuration and state data manipulated by the Network Configuration Protocol (NETCONF), NETCONF remote procedure calls, and NETCONF notifications. [STANDARDS-TRACK] Informative References Data models provide a programmatic approach to represent services and networks. Concretely, they can be used to derive configuration information for network and service components, and state information that will be monitored and tracked. Data models can be used during the service and network management life cycle (e.g., service instantiation, service provisioning, service optimization, service monitoring, service diagnosing, and service assurance). Data models are also instrumental in the automation of network management, and they can provide closed-loop control for adaptive and deterministic service creation, delivery, and maintenance. This document describes a framework for service and network management automation that takes advantage of YANG modeling technologies. This framework is drawn from a network operator perspective irrespective of the origin of a data model; thus, it can accommodate YANG modules that are developed outside the IETF. This document captures the current syntax used in YANG module tree diagrams. The purpose of this document is to provide a single location for this definition. This syntax may be updated from time to time based on the evolution of the YANG language.

Full Tree /nw:networks/network/ac-profile/name +--rw description? string +--rw l2-connection | +--rw encapsulation | | +--rw encap-type? identityref | | +--rw dot1q | | | +--rw tag-type? identityref | | | +--rw cvlan-id? uint16 | | | +--rw tag-operations | | | +--rw (op-choice)? | | | | +--:(pop) | | | | | +--rw pop? empty | | | | +--:(push) | | | | | +--rw push? empty | | | | +--:(translate) | | | | +--rw translate? empty | | | +--rw tag-1? dot1q-types:vlanid | | | +--rw tag-1-type? | | | | dot1q-types:dot1q-tag-type | | | +--rw tag-2? dot1q-types:vlanid | | | +--rw tag-2-type? | | | dot1q-types:dot1q-tag-type | | +--rw priority-tagged | | | +--rw tag-type? identityref | | +--rw qinq | | +--rw tag-type? identityref | | +--rw svlan-id uint16 | | +--rw cvlan-id uint16 | | +--rw tag-operations | | +--rw (op-choice)? | | | +--:(pop) | | | | +--rw pop? uint8 | | | +--:(push) | | | | +--rw push? empty | | | +--:(translate) | | | +--rw translate? uint8 | | +--rw tag-1? dot1q-types:vlanid | | +--rw tag-1-type? | | | dot1q-types:dot1q-tag-type | | +--rw tag-2? dot1q-types:vlanid | | +--rw tag-2-type? | | dot1q-types:dot1q-tag-type | +--rw (l2-service)? | | +--:(l2-tunnel-service) | | | +--rw l2-tunnel-service | | | +--rw type? identityref | | | +--rw pseudowire | | | | +--rw vcid? uint32 | | | | +--rw far-end? union | | | +--rw vpls | | | | +--rw vcid? uint32 | | | | +--rw far-end* union | | | +--rw vxlan | | | +--rw vni-id uint32 | | | +--rw peer-mode? identityref | | | +--rw peer-ip-address* inet:ip-address | | +--:(l2vpn) | | +--rw l2vpn-id? vpn-common:vpn-id | +--rw l2-termination-point? string | +--rw local-bridge-reference? string | +--rw bearer-reference? string | | {vpn-common:bearer-reference}? | +--rw lag-interface {vpn-common:lag-interface}? | +--rw lag-interface-id? string | +--rw member-link-list | +--rw member-link* [name] | +--rw name string +--rw ip-connection | +--rw l3-termination-point? string | +--rw ipv4 {vpn-common:ipv4}? | | +--rw local-address? | | | inet:ipv4-address | | +--rw prefix-length? uint8 | | +--rw address-allocation-type? | | | identityref | | +--rw (allocation-type)? | | +--:(dynamic) | | | +--rw (address-assign)? | | | | +--:(number) | | | | | +--rw number-of-dynamic-address? uint16 | | | | +--:(explicit) | | | | +--rw customer-addresses | | | | +--rw address-pool* [pool-id] | | | | +--rw pool-id string | | | | +--rw start-address | | | | | inet:ipv6-address | | | | +--rw end-address? | | | | inet:ipv6-address | | | +--rw (provider-dhcp)? | | | | +--:(dhcp-service-type) | | | | | +--rw dhcp-service-type? | | | | | enumeration | | | | +--:(service-type) | | | | +--rw (service-type)? | | | | +--:(relay) | | | | +--rw server-ip-address* | | | | inet:ipv6-address | | | +--rw (dhcp-relay)? | | | +--:(customer-dhcp-servers) | | | +--rw customer-dhcp-servers | | | +--rw server-ip-address* | | | inet:ipv6-address | | +--:(static-addresses) | | +--rw primary-address? | | | -> ../address/address-id | | +--rw address* [address-id] | | +--rw address-id string | | +--rw customer-address? inet:ipv6-address | +--rw ipv6 {vpn-common:ipv6}? | +--rw local-address? | | inet:ipv6-address | +--rw prefix-length? uint8 | +--rw address-allocation-type? | | identityref | +--rw (allocation-type)? | +--:(dynamic) | | +--rw (address-assign)? | | | +--:(number) | | | | +--rw number-of-dynamic-address? uint16 | | | +--:(explicit) | | | +--rw customer-addresses | | | +--rw address-pool* [pool-id] | | | +--rw pool-id string | | | +--rw start-address | | | | inet:ipv6-address | | | +--rw end-address? | | | inet:ipv6-address | | +--rw (provider-dhcp)? | | | +--:(dhcp-service-type) | | | | +--rw dhcp-service-type? | | | | enumeration | | | +--:(service-type) | | | +--rw (service-type)? | | | +--:(relay) | | | +--rw server-ip-address* | | | inet:ipv6-address | | +--rw (dhcp-relay)? | | +--:(customer-dhcp-servers) | | +--rw customer-dhcp-servers | | +--rw server-ip-address* | | inet:ipv6-address | +--:(static-addresses) | +--rw primary-address? | | -> ../address/address-id | +--rw address* [address-id] | +--rw address-id string | +--rw customer-address? inet:ipv6-address +--rw routing-protocols | +--rw routing-protocol* [id] | +--rw id string | +--rw type? identityref | +--rw routing-profiles* [id] | | +--rw id leafref | | +--rw type? identityref | +--rw static | | +--rw cascaded-lan-prefixes | | +--rw ipv4-lan-prefixes* [lan next-hop] | | | {vpn-common:ipv4}? | | | +--rw lan inet:ipv4-prefix | | | +--rw lan-tag? string | | | +--rw next-hop union | | | +--rw metric? uint32 | | | +--rw bfd-enable? boolean {vpn-common:bfd}? | | | +--rw preference? uint32 | | | +--rw status | | | +--rw admin-status | | | | +--rw status? identityref | | | | +--rw last-change? yang:date-and-time | | | +--ro oper-status | | | +--ro status? identityref | | | +--ro last-change? yang:date-and-time | | +--rw ipv6-lan-prefixes* [lan next-hop] | | {vpn-common:ipv6}? | | +--rw lan inet:ipv4-prefix | | +--rw lan-tag? string | | +--rw next-hop union | | +--rw metric? uint32 | | +--rw bfd-enable? boolean {vpn-common:bfd}? | | +--rw preference? uint32 | | +--rw status | | +--rw admin-status | | | +--rw status? identityref | | | +--rw last-change? yang:date-and-time | | +--ro oper-status | | +--ro status? identityref | | +--ro last-change? yang:date-and-time | +--rw bgp | | +--rw peer-groups | | | +--rw peer-group* [name] | | | +--rw name string | | | +--rw local-address? union | | | +--rw description? string | | | +--rw local-as? inet:as-number | | | +--rw peer-as inet:as-number | | | +--rw address-family? identityref | | | +--rw multihop? uint8 | | | +--rw as-override? boolean | | | +--rw allow-own-as? uint8 | | | +--rw prepend-global-as? boolean | | | +--rw send-default-route? boolean | | | +--rw site-of-origin? | | | | rt-types:route-origin | | | +--rw ipv6-site-of-origin? | | | | rt-types:ipv6-route-origin | | | +--rw redistribute-connected* [address-family] | | | | +--rw address-family identityref | | | | +--rw enable? boolean | | | +--rw bgp-max-prefix | | | | +--rw max-prefix? uint32 | | | | +--rw warning-threshold? decimal64 | | | | +--rw violate-action? enumeration | | | | +--rw restart-timer? uint32 | | | +--rw bgp-timers | | | | +--rw keepalive? uint16 | | | | +--rw hold-time? uint16 | | | +--rw authentication | | | +--rw enable? boolean | | | +--rw keying-material | | | +--rw (option)? | | | +--:(ao) | | | | +--rw enable-ao? boolean | | | | +--rw ao-keychain? | | | | key-chain:key-chain-ref | | | +--:(md5) | | | | +--rw md5-keychain? | | | | key-chain:key-chain-ref | | | +--:(explicit) | | | +--rw key-id? uint32 | | | +--rw key? string | | | +--rw crypto-algorithm? | | | identityref | | +--rw neighbor* [remote-address] | | +--rw remote-address inet:ip-address | | +--rw local-address? union | | +--rw peer-group? | | | -> ../../peer-groups/peer-group/name | | +--rw description? string | | +--rw local-as? inet:as-number | | +--rw peer-as inet:as-number | | +--rw address-family? identityref | | +--rw multihop? uint8 | | +--rw as-override? boolean | | +--rw allow-own-as? uint8 | | +--rw prepend-global-as? boolean | | +--rw send-default-route? boolean | | +--rw site-of-origin? | | | rt-types:route-origin | | +--rw ipv6-site-of-origin? | | | rt-types:ipv6-route-origin | | +--rw redistribute-connected* [address-family] | | | +--rw address-family identityref | | | +--rw enable? boolean | | +--rw bgp-max-prefix | | | +--rw max-prefix? uint32 | | | +--rw warning-threshold? decimal64 | | | +--rw violate-action? enumeration | | | +--rw restart-timer? uint32 | | +--rw bgp-timers | | | +--rw keepalive? uint16 | | | +--rw hold-time? uint16 | | +--rw authentication | | | +--rw enable? boolean | | | +--rw keying-material | | | +--rw (option)? | | | +--:(ao) | | | | +--rw enable-ao? boolean | | | | +--rw ao-keychain? | | | | key-chain:key-chain-ref | | | +--:(md5) | | | | +--rw md5-keychain? | | | | key-chain:key-chain-ref | | | +--:(explicit) | | | +--rw key-id? uint32 | | | +--rw key? string | | | +--rw crypto-algorithm? identityref | | +--rw status | | +--rw admin-status | | | +--rw status? identityref | | | +--rw last-change? yang:date-and-time | | +--ro oper-status | | +--ro status? identityref | | +--ro last-change? yang:date-and-time | +--rw ospf | | +--rw address-family? identityref | | +--rw area-id yang:dotted-quad | | +--rw metric? uint16 | | +--rw sham-links {vpn-common:rtg-ospf-sham-link}? | | | +--rw sham-link* [target-site] | | | +--rw target-site string | | | +--rw metric? uint16 | | +--rw max-lsa? uint32 | | +--rw authentication | | | +--rw enable? boolean | | | +--rw keying-material | | | +--rw (option)? | | | +--:(auth-key-chain) | | | | +--rw key-chain? | | | | key-chain:key-chain-ref | | | +--:(auth-key-explicit) | | | +--rw key-id? uint32 | | | +--rw key? string | | | +--rw crypto-algorithm? identityref | | +--rw status | | +--rw admin-status | | | +--rw status? identityref | | | +--rw last-change? yang:date-and-time | | +--ro oper-status | | +--ro status? identityref | | +--ro last-change? yang:date-and-time | +--rw isis | | +--rw address-family? identityref | | +--rw area-address area-address | | +--rw level? identityref | | +--rw metric? uint16 | | +--rw mode? enumeration | | +--rw authentication | | | +--rw enable? boolean | | | +--rw keying-material | | | +--rw (option)? | | | +--:(auth-key-chain) | | | | +--rw key-chain? | | | | key-chain:key-chain-ref | | | +--:(auth-key-explicit) | | | +--rw key-id? uint32 | | | +--rw key? string | | | +--rw crypto-algorithm? identityref | | +--rw status | | +--rw admin-status | | | +--rw status? identityref | | | +--rw last-change? yang:date-and-time | | +--ro oper-status | | +--ro status? identityref | | +--ro last-change? yang:date-and-time | +--rw rip | | +--rw address-family? identityref | | +--rw timers | | | +--rw update-interval? uint16 | | | +--rw invalid-interval? uint16 | | | +--rw holddown-interval? uint16 | | | +--rw flush-interval? uint16 | | +--rw default-metric? uint8 | | +--rw authentication | | | +--rw enable? boolean | | | +--rw keying-material | | | +--rw (option)? | | | +--:(auth-key-chain) | | | | +--rw key-chain? | | | | key-chain:key-chain-ref | | | +--:(auth-key-explicit) | | | +--rw key? string | | | +--rw crypto-algorithm? identityref | | +--rw status | | +--rw admin-status | | | +--rw status? identityref | | | +--rw last-change? yang:date-and-time | | +--ro oper-status | | +--ro status? identityref | | +--ro last-change? yang:date-and-time | +--rw vrrp | +--rw address-family? identityref | +--rw vrrp-group? uint8 | +--rw backup-peer? inet:ip-address | +--rw virtual-ip-address* inet:ip-address | +--rw priority? uint8 | +--rw ping-reply? boolean | +--rw status | +--rw admin-status | | +--rw status? identityref | | +--rw last-change? yang:date-and-time | +--ro oper-status | +--ro status? identityref | +--ro last-change? yang:date-and-time +--rw oam | +--rw bfd | +--rw profile? leafref | +--rw session-type? identityref | +--rw desired-min-tx-interval? uint32 | +--rw required-min-rx-interval? uint32 | +--rw local-multiplier? uint8 | +--rw holdtime? uint32 | +--rw authentication! | | +--rw key-chain? key-chain:key-chain-ref | | +--rw meticulous? boolean | +--rw status | +--rw admin-status | | +--rw status? identityref | | +--rw last-change? yang:date-and-time | +--ro oper-status | +--ro status? identityref | +--ro last-change? yang:date-and-time +--rw security +--rw encryption {vpn-common:encryption}? | +--rw enabled? boolean | +--rw layer? enumeration +--rw encryption-profile +--rw (profile)? +--:(provider-profile) | +--rw profile-name? leafref +--:(customer-profile) +--rw customer-key-chain? key-chain:key-chain-ref ]]>

Acknowledgments TODO acknowledge.