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| -rw-r--r-- | doc/bird.sgml | 29 |
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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"; } <sect1>BGP +<p>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. + +<p>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). + +<p>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. + +<p>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. + +<sect2>Configuration + +<sect2>Attributes + +<sect2>Example + <sect1>Device <p>The Device protocol is not a real routing protocol as it doesn't generate |