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12.2 Commands for configuring a Route Server

Now we will describe the commands that have been added to quagga in order to support the route server features.

Route-Server: neighbor peer-group route-server-client
Route-Server: neighbor A.B.C.D route-server-client
Route-Server: neighbor X:X::X:X route-server-client

This command configures the peer given by peer, A.B.C.D or X:X::X:X as an RS-client.

Actually this command is not new, it already existed in standard Quagga. It enables the transparent mode for the specified peer. This means that some BGP attributes (as-path, next-hop and MED) of the routes announced to that peer are not modified.

With the route server patch, this command, apart from setting the transparent mode, creates a new Loc-RIB dedicated to the specified peer (those named ‘Loc-RIB for X’ in Figure 12.2.). Starting from that moment, every announcement received by the route server will be also considered for the new Loc-RIB.

Route-Server: neigbor {A.B.C.D|X.X::X.X|peer-group} route-map WORD {import|export}

This set of commands can be used to specify the route-map that represents the Import or Export policy of a peer which is configured as a RS-client (with the previous command).

Route-Server: match peer {A.B.C.D|X:X::X:X}

This is a new match statement for use in route-maps, enabling them to describe import/export policies. As we said before, an import/export policy represents a set of input/output filters of the RS-client. This statement makes possible that a single route-map represents the full set of filters that a BGP speaker would use for its different peers in a non-RS scenario.

The match peer statement has different semantics whether it is used inside an import or an export route-map. In the first case the statement matches if the address of the peer who sends the announce is the same that the address specified by {A.B.C.D|X:X::X:X}. For export route-maps it matches when {A.B.C.D|X:X::X:X} is the address of the RS-Client into whose Loc-RIB the announce is going to be inserted (how the same export policy is applied before different Loc-RIBs is shown in Figure 12.2.).

Route-map Command: call WORD

This command (also used inside a route-map) jumps into a different route-map, whose name is specified by WORD. When the called route-map finishes, depending on its result the original route-map continues or not. Apart from being useful for making import/export route-maps easier to write, this command can also be used inside any normal (in or out) route-map.

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