Distribution of Traffic Engineering Extended
Administrative Groups Using the Border Gateway Protocol - Link State (BGP-LS)Microsoftjefftant.ietf@gmail.comHuaweiYuhua District101 Software AvenueNanjingJiangsu210012Chinawangzitao@huawei.comHuaweiYuhua District101 Software AvenueNanjingJiangsu210012Chinabill.wu@huawei.comCisco Systemsketant@cisco.com
Routing Area
IDR Working GroupInter-Domain RoutingAdministrative groups are link attributes used for traffic
engineering. This document defines an extension to the Border Gateway Protocol -
Link State (BGP-LS) for advertisement of extended administrative groups (EAGs).IntroductionAdministrative groups (commonly referred to as "colors" or "link colors")
are link attributes that are advertised by link-state protocols like IS-IS , OSPFv2 , and OSPFv3 .
The Border Gateway Protocol - Link State (BGP-LS) advertisement of the originally defined (non-extended) administrative groups is encoded
using the Administrative Group (color) TLV 1088 as defined in .These administrative groups are defined as a fixed-length 32-bit
bitmask. As networks grew and more use cases were introduced, the 32-bit
length was found to be constraining, and hence extended administrative
groups (EAGs) were introduced in .The EAG TLV () is not a replacement for the Administrative
Group (color) TLV; as explained in , both values can coexist.
It is out of scope for this document to specify the behavior of the
BGP-LS consumer . This document specifies an extension to BGP-LS for advertisement of the
extended administrative groups.Requirements LanguageThe 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.Advertising Extended Administrative Groups in BGP-LSThis document defines an extension that enables BGP-LS speakers to
signal the EAG of links in a network to a BGP-LS consumer of network
topology such as a centralized controller. The centralized controller
can leverage this information in traffic engineering computations and
other use cases. When a BGP-LS speaker is originating the topology
learned via link-state routing protocols like OSPF or IS-IS, the EAG
information of the links is sourced from the underlying extensions as
defined in .The EAG of a link is encoded in a new Link Attribute TLV using the following format:Where:
Type:
1173
Length:
variable length that represents the total length of the value field in octets.
The length value MUST be a multiple of 4. If the length is not a multiple of 4, the TLV MUST be considered malformed.
Value:
one or more sets of 32-bit bitmasks that indicate the
administrative groups (colors) that are enabled on the link when
those specific bits are set.
IANA ConsiderationsIANA has assigned a code point from the "BGP-LS Node Descriptor, Link Descriptor, Prefix Descriptor, and Attribute TLVs" registry as described in the following table.
Code Point
Description
IS-IS TLV/Sub-TLV
1173
Extended Administrative Group
22/14
Manageability ConsiderationsThe new protocol extensions introduced in this document augment the
existing IGP topology information that is distributed via . Procedures and protocol extensions defined in this
document do not affect the BGP protocol operations and management other
than as discussed in Section "Manageability Considerations" of . Specifically, the tests for malformed attributes, to perform
syntactic checks as described in Section "Fault Management" of , now encompass the new BGP-LS Attribute TLV defined
in this document. The semantic or content checking for the TLV
specified in this document and its association with the BGP-LS Network Layer Reachability Information (NLRI)
types or its BGP-LS Attribute are left to the consumer of the BGP-LS
information (e.g., an application or a controller) and not to BGP itself.A consumer of the BGP-LS information retrieves this information over
a BGP-LS session (refer to Sections and of ).Security ConsiderationsThe procedures and protocol extensions defined in this document do not
affect the BGP security model. See the "Security Considerations" section of
for a discussion of BGP security.
This document only introduces a new Attribute TLV, and any syntactic
error in it would result in the BGP-LS Attribute being discarded .
Also, refer to and for analyses of security issues for BGP.
Security considerations for acquiring and distributing BGP-LS information are discussed in .
The TLV introduced in this document is used to propagate the EAG
extensions defined in .
It is assumed that the IGP instances originating this TLV will support any required security mechanisms for OSPF and IS-IS, in order to prevent any security
issues when propagating the Sub-TLVs into BGP-LS.Security concerns for OSPF are addressed in , , and .
Further security analysis for the OSPF protocol is done in .Security considerations for IS-IS are specified by .The advertisement of the link attribute information defined in this
document presents no significant additional risk beyond that associated with the
existing link attribute information already supported in .ReferencesNormative ReferencesInformative ReferencesAcknowledgmentsThe authors would like to thank , , , , and for their reviews and valuable comments.