BMP Loc-RIB: Peer address

In this section, we describe a solution based on BMPv4 TLVs. describes a BMPv4 TLV used to convey the peer address. introduces optional TLVs for the case of paths imported from another VRF.

In BMPv4, TLV's can be used to provide optional information along with monitored paths. Peer Address information can be included using one such TLV. A TLV type "Rx Peer-Address TLV" needs to be reserved from the BMP Route Monitoring TLVs registry. The value of the TLV is the "Address Type" code followed by the address of the peer from which the monitored path was received. The address type 0 is reserved. A set of address types is described in the following subsections. The value of the type field of this TLV is &IANA_RX_PEER_ADDR_TLV;. The length field is one (for the "Address Type" field) plus the length of the "Rx Peer Address" field. The "Index" field is, as described by , not included in the length. The TLV structure is illustrated in .

The "Rx Peer-Address TLV" may describe a self originated path by setting the value of the "Address Type" to 1. The "Rx Peer Address" is empty. The "Length" is thus set to 1.

In case of a BGP peering established using IPv4, the "Address Type" is set to 2. The "Rx Peer Address" is the 4 bytes IPv4 Address of the peer. The "Length" is thus set to 5.

In case of a BGP peering established using an IPv6 Global Link Address, the "Address Type" is set to 3. The "Rx Peer Address" is the 16 bytes IPv6 Global Link Address of the peer. The "Length" is thus set to 17.

In some scenarii, for example in the case case of a BGP peering established using IPv6 Link Local Addresses, an interface identifier is needed to disambiguate the address. The "Address Type" is set to 4. The "Rx Peer Address" is the 16 bytes IPv6 Address of the peer, followed by an interface ID of a variable size S. The "Length" is thus set to 1 + 16 + S.

In the same cases as but with interfaces identified using a name instead of an ID, the "Address Type" is set to 5. The "Rx Peer Address" is the 16 bytes IPv6 Address of the peer, followed by an interface name of a variable size S, encoded in UTF-8 without specific termination characters. The "Length" is thus set to 1 + 16 + S.

Path information advertised through BMP Loc-RIB might be related to a path imported from another VRF. In that scenario, the sole knowledge of the remote peer IP address is not sufficient to obtain a clear picture of where this path was coming from.

A TLV type "Origin VRF TLV" needs to be reserved from the BMP Route Monitoring TLVs registry. It describes the VRF context in which this path was received from a peer or where it was self-originated. It contains a variable length field matching the definition of VRF/Table name from . The value of the type field of this TLV is &IANA_ORIGIN_VRF_TLV;. The length field of this BMPv4 TLV is the length, in bytes, of the UTF-8 string of the VRF name. When this TLV is present, the Rx Peer-Address TLV associated with that path refers to the IP address of the peer from which it was received, in the VRF context refered in this TLV. This TLV is illustrated in .

A TLV type "Previous VRF TLV" needs to be reserved from the BMP Route Monitoring TLVs registry. It describes the VRF from which this path was imported. It contains a variable length field matching the definition of VRF/Table name from . The value of the type field of this TLV is &IANA_PREV_VRF_TLV;. The length field of this is the length, in bytes, of the UTF-8 string of the VRF name. This TLV is illustrated in .

As an example, if BMP Loc-RIB describes a path P in VRF C, which was received from a peer I in VRF A, imported into VRF B, and finally imported from VRF B into VRF C, the Origin VRF Name is A, the Previous VRF Name is B, the VRF/Table Name TLV (as per is C, and the Rx Peer-Adress TLV is I.

A TLV type "Previous VRF Sequence" needs to be reserved from the BMP Route Monitoring TLVs registry. It describes the entire chain of VRFs through which this path was imported before landing in the current VRF. The list starts with the previous VRF, and ends with the Origin VRF in which this path was received or originated. One entry of this list has the format described in . The length field is an 8 bit value capturing the length, in bytes, of the Name field. The name field is the VRF name of the described VRF of the sequence, matching the definition of VRF/Table name from . A complete Previous VRF Sequence TLV structure is illustrated in .

The value of the type field of this TLV is &IANA_PREV_VRF_SEQ_TLV;. The length of a "Previous VRF Sequence" TLV is the sum of the total lengths of each VRF entry in the sequence (1 byte for the length field + the value of the length field). This does not include the length of the Index field as defined in . In the example above , the sequence listed in the Previous VRF sequence would be [B, A].

This document requests that IANA assign the following new parameters to the "BMP Route Monitoring TLVs" registry Type = &IANA_RX_PEER_ADDR_TLV;: Rx Peer-Address TLV type. The value of this TLV is defined in Type = &IANA_ORIGIN_VRF_TLV;: Origin VRF TLV type. The value of this TLV is defined in Type = &IANA_PREV_VRF_TLV;: Previous VRF TLV type. The value of this TLV is defined in Type = &IANA_PREV_VRF_SEQ_TLV;: Previous VRF Sequence TLV type. The value of this TLV is defined in This document also requests the definition of a "Local-RIB Peer Address" registry seeded as follows: Type = 1: Self-Originated address type. Set to 1 if the route described by the BGP PDU enclosed in the BMP Route Monitoring Message was originated from the BMP station (router). Type = 2: IPv4 address type. Set to 2 if the following Peer Address contained in the Rx Peer-Address TLV is an IPv4 address. Type = 3: Global Link IPv6 address type. Set to 3 if the following Peer Address contained in the Rx Peer-Address TLV is a Global Link IPv6 address. Type = 4: IPv6 + Interface ID address type. Set to 4 if the following Peer Address contained in the Rx Peer-Address TLV is an IPv6 address followed by a numerical interface ID of variable size. Type = 5: IPv6 + Interface Name address type. Set to 5 if the following Peer Address contained in the Rx Peer-Address TLV is an IPv6 address followed by an interface name encoded as an UTF-8 string of variable size.