Technical data

Gateway Routing Daemon (GATED) Configuration Reference
A.18 Control Statements
Nonrouting by Protocol
proto default | aggregate
restrict ;
proto default | aggregate
[ metric metric ]{
route_filter [ restrict | ( metric metric )];
};
These protocols can only be referenced by protocol.
• default refers to routes created by the gendefault option. It is recommended
that route generation be used instead.
• aggregate refers to routes synthesized from other routes when the aggregate
and generate statements are used. See Section A.18.6 for more information.
Exporting by AS Path
proto proto | all aspath aspath_regexp
origin any | ( [ igp ] [egp ] [ incomplete ] )
restrict ;
proto proto | all aspath aspath_regexp
origin any | ( [ igp ] [egp ] [ incomplete ] )
[ metric metric ]{
route_filter [ restrict | ( metric metric )];
};
When BGP is configured, all routes are assigned an AS path when they are
added to the routing table. For all interior routes, this AS path specifies IGP as
the origin and no AS in the AS path; the current AS is added when the route
is exported. For EGP routes, this AS path specifies EGP as the origin and the
source AS as the AS path. For BGP routes, the AS path is stored as learned from
BGP.
AS path regular expressions are described in Section A.18.2>
Exporting by Route Tag
proto proto | all tag tag restrict ;
proto proto | all tag tag
[ metric metric ] {
route_filter [ restrict | ( metric metric ) ] ;
};
Both OSPF and RIP version 2 currently support tags, all other protocols always
have a tag of zero. The source of exported routes may be selected based on this
tag. This is useful when routes are classified by tag when they are exported into
a given routing protocol.
A.18.6 Route Aggregation
Route aggregation is a method of generating a more general route given the
presence of a specific route. It is used, for example, at an autonomous system
border to generate a route to a network to be advertised using EGP, if one or
more subnets of that network have been learned using RIP. Older versions of
GATED automatically performed this function, generating an aggregate route
to a natural network (using the old Class A, B and C concept), if there is an
interface to a subnet of that natural network. However, that was not always
the correct thing to do, and, with the advent of classless interdomain routing it
is even more frequently the wrong thing to do. Therefore, aggregation must be
explicitly configured. No aggregation is performed unless explicitly requested in
an aggregate statement.
Gateway Routing Daemon (GATED) Configuration Reference A–41