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).

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Border Gateway Protocol

This information is sufficient for constructing a graph of AS connectivity, from which routing loops may be pruned, and, at the AS level, some policy decisions may be enforced. For each newly received or replacement feasible route, the local BGP speaker determines a degree rcf preference as follows: BGP may be used for routing within an hgp system.

Therefore, in addition to local Routing Table stability, this check also improves behavior of the protocol in the network. With damping, a route’s flapping is exponentially decayed.

This, in turn, reflects the set of policy decisions that can and cannot be enforced using BGP. If AS2 wants to send data to rfv For example, a directly connected prefix, learned from the router’s own hardware, is usually most preferred. In the “Active” state, the router resets the ConnectRetry timer to zero and returns to the “Connect” state. Multiple Networks Per Message Route Resolvability Condition As indicated in Section 9. BGP provides mechanisms by which a BGP speaker can inform its peers that a previously advertised route is no longer available for use.

RFC – part 1 of 4

External peer Peer that is in a different Autonomous System than the local system. 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 become congested while the other links remain under-utilized, because external networks all picked that set of congested paths as optimal.


This allows for automatic and decentralized routing of traffic across the Internet, but it also leaves the Internet potentially vulnerable to accidental or malicious disruption, known as BGP hijacking.

It notes that a distinct key should be used for communication with each protected peer. Views Read Edit View history.

In common practice, [14] only one of the confederation AS numbers is seen by the Internet as a whole. This causes scaling problems, since the number of required connections grows quadratically with the number of routers involved.

The IANA registry therefore provides different number ranges for the attribute types. If such a message exists, the new address prefix is appended to it. In the “OpenSent” state, the router sends an Open message and waits for one in return in order to transition to the “OpenConfirm” state.

Intellectual Property The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the rdc or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights.

Supported Standards for BGP

New text has been added to define semantics associated with IP prefixes. We show that the current damping design leads to the intended behavior only under persistent route flapping. Autonomous System AS The classic definition of an Autonomous System is a set of routers under a single technical administration, using an interior gateway protocol IGP and common metrics to determine how to route packets within the AS, and using an inter-AS routing protocol to determine how to route packets to other ASes.

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Controlling Routing Traffic Overhead If such a route were ever used, a routing loop could result.

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

The suggested default amount of jitter SHALL be determined by multiplying the base value of the appropriate timer by a random factor, which bbp uniformly distributed in the range from 0. Path Attribute Ordering Implementations that combine update messages as described above in Section 6. Other commercial routers may need a specific software executable image that contains BGP, or a license that enables it.

These mechanisms include support for advertising a set of destinations as an IP prefix and eliminating the concept of network “class” within BGP.

Frequency of Route Advertisement It is critical that BGP speakers within an AS do not make conflicting decisions regarding route selection that would cause forwarding loops to occur. Breaking Ties Phase However, a bit in the type field within the attribute decides whether the encoded extended community is of a transitive or non-transitive nature. A group of destinations which share some common property.

Due to the extended attribute range, its usage can be manifold.