Bgp Introduction - Edge-Core ES4626 User Manual

Example:
Switch#show ipv6 ospf virtual-links
Virtual Link VLINK1 to router 5.6.7.8 is up
Transit area 0.0.0.1 via interface Vlan1, instance ID 0
Local address 3ffe:1234:1::1/128
Remote address 3ffe:5678:3::1/128
Transmit Delay is 1 sec, State Point-To-Point,
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
Hello due in 00:00:01
Adjacency state Up
17.8 BGP

17.8.1 BGP Introduction

BGP stands for a Border Gateway Protocol.It's a dynamic routing protocol
inter-autonomous system. Its basic function is automatically exchanging routing
information without loops. By exchanging routing reachable information with autonomous
number of AS sequence attributes, BGP could create autonomous topological map to
eliminate routing loop and implement policies configured by users. Generally, the
switches in an AS may use several IGPs (Interior Gateway Protocol) in order to exchange
routing information in the AS, such as RIP and OSPF which are IGPs; and exchange
information among ASes with EGP (Exterior Gateway Protocol). For example, BGP is
one kind of EGP. The AS is usually established on a single administrative department.
BGP is often used on the switches among ISPs or the departments of Multi-national
Corporation.
BGP has been used since1989, its earliest three versions are RFC1105（BGP-1）、
RFC1163 （BGP-2）and RFC1267（BGP-3）.Currently, the most popular one is RFC1771
（BGP-4）. The ES4626/ES4650 switch supports BGP-4.
Characteristics of BGP-4
1．
BGP-4 is suitable for the distributed structure and supports Classless InterDomain
Routing (CIDR). BGP-4 is becoming the virtual exterior routing protocol standard used for
the global Internet. The features of BGP-4 are as follows.
BGP is an exterior routing protocol, unlike interior routing protocol, such as OSPF
and RIP, BGP can't discovery and calculate routes, but it can control the transmission of
routes and select the best route.
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