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. The combination of unit type and unsigned integer value is used
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.This document retains the basic format of Link Bandwidth Extended
Community, uses several special subtypes to identify different bandwidth
units, and uses a combination of units and integers to accurately
represent a specific bandwidth value.bps Link Bandwidth, subtype is TBD. The value of bandwidth in the
Local Administrator subfield is an unsigned integer. The unit of
this type of link bandwidth is bps.Kbps Link Bandwidth, subtype is TBD. The value of bandwidth in
the Local Administrator subfield is an unsigned integer. The unit of
this type of link bandwidth is Kbps.Mbps Link Bandwidth, subtype is TBD. The value of bandwidth in
the Local Administrator subfield is an unsigned integer. The unit of
this type of link bandwidth is Mbps.Gbps Link Bandwidth, subtype is TBD. The value of bandwidth in
the Local Administrator subfield is an unsigned integer. The unit of
this type of link bandwidth is Gbps.Tbps Link Bandwidth, subtype is TBD. The value of bandwidth in
the Local Administrator subfield is an unsigned integer. The unit of
this type of link bandwidth is Tbps.We can use different unit bandwidth values to identify the required
bandwidth.The subtypes defined here can be used for both optional transitive
and non-transitive extended community attributes.In network deployment, a routing policy may be used to match the link
bandwidth advertised by BGP link bandwidth extended community, based on
the mechanisms of this document, the operator can specify the bandwidth
in different units as required, so that exact value matching can be
achieved.Bandwidths of different units may be used together. For example, an
link bandwidth extended community with the type Gbps and value 1, and
another link bandwidth extended community with the type Mbps and value
500 may be used to represent 1.500 Gbps. However, it is RECOMMENDED to
use a single link bandwidth extended community with the type Mbps and
value 1500 Mbps to achieve the same purpose.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.