Extension of Link Bandwidth Extended
CommunityHuawei TechnologiesHuawei Campus, No. 156 Beiqing RoadBeijing100095Chinaliwenyan@huawei.comHuawei TechnologiesHuawei Campus, No. 156 Beiqing RoadBeijing100095Chinarainsword.wang@huawei.comHuawei TechnologiesHuawei Campus, No. 156 Beiqing RoadBeijing100095Chinajie.dong@huawei.com defines a BGP link
bandwidth extended community attribute, which can enable devices to
implement unequal-cost load-balancing. However, the bandwidth value
encapsulated by the extended community attribute is of the
floating-point type, which is inconvenient to use. In this document, a
set of new types of link bandwidth extended community are introduced to
facilitate the configuration and calculation of link bandwidth.The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119.In , the link bandwidth
extended community attribute is added to implement unequal-cost load
balancing based on the bandwidth on a path. As defined in the draft, the
bandwidth of a link is expressed in 4-octets in IEEE floating-point
format.In practice, the use of this floating-point format may result errors
in configuration and computation. When an operator needs to manually
specify the bandwidth, you also need to consider the conversion from the
bandwidth value to the floating-point number. This mode is not
user-friendly, especially when the routing policy is used for bandwidth
matching.This document introduce a more intuitive expression of link bandwidth
in BGP. It uses an unsigned long integer value to describe the link
bandwidth value. This is easier for operators to use and understand, and
can avoid configuration and computation errors.The type of Link Bandwidth Extended Community is 0x40, and the
subtype is 0x04. In the attribute value, the global administrator
subfield is set to the AS number of the route to which the Link
Bandwidth attribute is added. In the local administrator subfield, the
link bandwidth value is set
to the IEEE floating-point type.A new type of IPv6 Address Specific Extended Community is added in this document. The ASN field of this
attribute is set to the AS number of the route to which the link
bandwidth attribute is added. The Link Bandwidth value field (8 bytes)
is set to the link bandwidth. The following extended contents are
added:The value of the high-order octet of the extended Type, refer to
, It is recommended that 0x03 and 0x43 be
used.New Link Bandwidth, subtype is TBD. The value of the Link
Bandwidth subfield is an unsigned long integer, in bytes per
second.The subtypes defined here can be used for both optional transitive
and non-transitive extended community attributes.The extended link bandwidth extended community attribute in this
document should not be used together with the standard link bandwidth
extended community attribute. If a route carries both the standard link
bandwidth extended community attribute and the unit link bandwidth
extended community attribute, the standard link bandwidth extended
community attribute is ignored.In actual deployment, if a routing policy is used to match link
bandwidth attributes, you can directly perform exact value matching.This document defines a specific application of the two-octet AS
specific extended community. IANA is requested to assign new sub-types
for both non-transitive and transitive extended communities.There are no additional security risks introduced by this design.