Bgp Command Set - ADTRAN AOS Version R10.1.0 Command Reference Manual

Command Reference Guide
BGP C
OMMAND
BGP is an Exterior Gateway Protocol (EGP) that is used within the Internet and multinational
organizations. EGP is one of two different types of dynamic routing protocols. The other protocol is
Interior Gateway Protocol (IGP). The difference between the two protocols is that IGPs (for example,
Routing Information Protocol (RIP), Open Shortest Path First (OSPF)) operate within an autonomous
system (AS), whereas EGPs allow routes to be exchanged between different autonomous systems.
Typically, an AS is defined by the boundaries of an organization. As an EGP, BGP routes must regulate
traffic between networks controlled by organizations with different policies. BGP is designed to allow
administrators to customize a policy for route exchange. The following are some characteristics of BGP
that make it an appropriate protocol for connecting different autonomous systems:
• BGP can filter both the routes it receives and those that it sends according to bit length, thereby mini-
mizing the number of routes exchanged.
• BGP uses policies to determine best routes rather than per-hop counts used in RIP or link states used in
OSPF. Each AS can set their own policy.
• BGP routers communicate only with manually configured neighbors.
• You can configure different policies for route exchange with different neighbors.
• Multiple VPN Routing and Forwarding (Multi-VRF) BGP allows each VRF instance from the service
provider its own BGP session within the router, thus extending the VRF instance from the service pro-
vider to the router.
In AOS firmware release 18.03.00, Multi-VRF BGP functionality was incorporated into AOS. This release
allows BGP configuration to occur on different VRF instances, and changes the hierarchical structure of
BGP within AOS, as well as the configuration steps necessary for BGP configuration. In addition, in AOS
firmware release R10.1.0, support for multiprotocol BGP and Internet Protocol version 6 (IPv6) BGP were
added.
The following are new features of BGP included with Multi-VRF BGP.
Address families (AFs) are used in BGP to maintain a separation between Internet protocol types within a
VRF instance. With the advent of Multi-VRF BGP in 18.03.00, AOS implemented the use of AFs into the
BGP hierarchical structure. An AF is a configuration structure that can reside at the default VRF instance
and within a nondefault VRF instance. Creating an address family enables processing of that address
family within a VRF, and it provides a place for AF-specific configuration.
In addition to the use of AFs, Multi-VRF BGP also allows the recognition and configuration of VRF
instances specific to BGP functionality within the router. This allows the VRF constructs from the service
provider to be incorporated into the customer router.
Multi-VRF is an application of the typical BGP functionality. As the name suggests, Multi-VRF BGP
extends traditional service provider multi-VRF functionality of BGP to the customer edge router. This type
of feature is typically used in Layer 3 virtual private network (VPN) applications where the VPN is
extended to the customer device using Multi-VRF. Multi-VRF BGP allows the customer edge router to
dynamically exchange customer VPN routers to and through the provider's VPN cloud, thus eliminating
the reliance on the provider to manage static routes. Multi-VRF takes place on the link between the service
provider's routers and the customer edge equipment.
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Copyright © 2012 ADTRAN, Inc.

BGP Command Set

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