From 56ab03c71f35c6c360b58b88f9e524c97714fdf6 Mon Sep 17 00:00:00 2001 From: Martin Mares Date: Mon, 29 May 2000 13:47:18 +0000 Subject: [PATCH] Added introduction to BGP. --- doc/bird.sgml | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) diff --git a/doc/bird.sgml b/doc/bird.sgml index ca7af0ec..a3669572 100644 --- a/doc/bird.sgml +++ b/doc/bird.sgml @@ -453,6 +453,35 @@ if 1234 = i then printn "."; else { print "*** FAIL: if 1 else"; } BGP +

The Border Gateway Protocol is the routing protocol used for backbone +level routing in today's Internet. Contrary to other protocols, its convergence +doesn't rely on all routers following the same rules for route selection, +making it possible to implement any routing policy at any router in the +network, the only restriction being that if a router advertises a route, +it must accept and forward packets according to it. + +

BGP works in terms of autonomous systems (often abbreviated as AS). Each +AS is a part of the network with common management and common routing policy. +Routers within each AS usually communicate using either a interior routing +protocol (such as OSPF or RIP) or an interior variant of BGP (called iBGP). +Boundary routers at the border of the AS communicate with their peers +in the neighboring AS'es via exterior BGP (eBGP). + +

Each BGP router sends to its neighbors updates of the parts of its +routing table it wishes to export along with complete path information +(a list of AS'es the packet will travel through if it uses that particular +route) in order to avoid routing loops. + +

In BIRD, each instance of BGP corresponds to one neighboring router. +This allows to set routing policy and all other parameters differently +for each neighbor. + +Configuration + +Attributes + +Example + Device

The Device protocol is not a real routing protocol as it doesn't generate