A Border Gateway Protocol 4 (BGP-4), January Canonical URL: https:// ; File formats: Plain Text PDF; Status: DRAFT. Border Gateway Protocol (BGP) is a standardized exterior gateway protocol designed to RFC corrected errors, clarified ambiguities and updated the. RFC (part 1 of 4): A Border Gateway Protocol 4 (BGP-4).

Author: Kataxe Maushicage
Country: Malta
Language: English (Spanish)
Genre: Science
Published (Last): 27 July 2012
Pages: 149
PDF File Size: 14.28 Mb
ePub File Size: 14.36 Mb
ISBN: 581-2-68651-883-4
Downloads: 3486
Price: Free* [*Free Regsitration Required]
Uploader: Mikatilar

This segment is then placed between the two consecutive ASes identified in a of the aggregated attribute.

This requires a reboot on most routers. These mechanisms include support for advertising a 4721 of destinations as an IP prefix, and eliminating the concept of network “class” within BGP.

Border Gateway Protocol

With the introduction 4217 32 bits AS numbers, some issues were immediately obvious with the community attribute that only defines a 16 bits ASN field, which prevents the matching between this field and the real ASN value.

The output of the Decision Process is the set of routes that will be advertised to peers; the selected routes will be stored in the local speaker’s Adj-RIBs-Out, according to policy. The IANA registry therefore provides different number ranges for btp attribute types.

Once the interface goes down, and there are no more preferred routes, the Loc-RIB route would be installed in the main routing table. By eligible to be submittedBGP will submit the routes that it considers best to the main routing table process.

RFC A Border Gateway Protocol 4 (BGP-4) – Wikidata

Terms “active” and “passive” Use of the Marker field for authentication has been deprecated. Since this classic definition was developed, it bbgp become common for a single AS to use several IGPs and, sometimes, several sets of metrics within an AS. Note that the latter may result in formation of persistent routing loops.

On the Internet, a BGP routing change may cause outages for several minutes. Efc method of doing this is to limit the rate of updates.


Other commercial routers may need a specific software executable image that contains BGP, or a license that enables it. During the peering handshake, when OPEN messages are exchanged, BGP speakers can negotiate [7] optional capabilities of the session, including multiprotocol extensions and various recovery modes. To facilitate this, it is a useful optimization to order the path attributes according to type code. Border Gateway Protocol BGP is a standardized exterior gateway protocol designed to exchange routing and reachability information among autonomous systems AS on the Internet.

Please integrate the section’s contents into the article as a whole, or rewrite the material. Aggregation can occur as part of the Decision Process to reduce the amount of routing information that will be placed in the Adj-RIBs-Out. It should also be noted that the community attribute is transitive, but communities applied by the customer very rarely become propagated outside the next-hop AS.

All other cases are outside the scope of this document. MEDs, defined in the main BGP standard, were originally intended to show to another neighbor AS the advertising AS’s preference as to which of several links are preferred for inbound traffic.

In large networks, this number of sessions may degrade performance of routers, due to either a lack of memory, or high CPU process requirements. Views Read Edit View history.

RFC – part 4 of 4

With the elimination of IP routing protocols that do not support classless routing, and the elimination of router and host implementations that do not support classless routing, there is no longer a need to de-aggregate.

However, absent a standard mechanism for effecting such changes in a coordinated fashion between peers, one cannot assume that BGP-4 implementations complying with this RFC will support frequent key 42711. As long as that directly connected route’s interface is bbp, the BGP route to the destination will not be put into the routing table. To alleviate the problem, BGP implements two options: For a multi-homed network, if it announces the same network blocks across all of its BGP peers, the result may be that one or several of its inbound links rdc congested while the other links remain under-utilized, because external networks all picked that set of congested paths as optimal.


BGP is an inter-Autonomous System routing protocol.

Supported Standards for BGP

Mutually recursive routes routes resolving each other or themselves also fail the resolvability check. Efficient Organization of Routing Information This is also described in the following procedure: If a particular AS has multiple BGP speakers and is providing transit service for other ASes, btp care must be taken to ensure a consistent view of routing 471 the AS.

Route aggregation and information reduction techniques see Section 9. Once candidate routes are received from neighbors, the Loc-RIB software applies additional tie-breakers to routes to the same destination.

From Wikipedia, the free encyclopedia. Such manipulation is outside the scope of the standard but is bg used. This is also described in the following procedure. If AS2 wants to send data to prefix These route-propagation rules effectively require that all iBGP peers inside an AS are interconnected in a full mesh.

Finally, we would like to thank all the members of the IDR Working Group for their ideas and the support they have given to this document. On the other hand, BGP can support any policy conforming to the destination-based forwarding paradigm. 42271, each should key also be chosen to be difficult for an attacker to guess.