3Com 7757 Configuration Manual page 357

Importing Routes
c
Configuring BGP Route
Aggregation
Configuring the Way to Advertise/Receive Routing Information
With BGP employed, an AS can send its interior routing information to its
neighbor ASs. However, the interior routing information is not generated by BGP,
it is obtained by importing IGP routing information to BGP routing table. Once IGP
routing information is imported to BGP routing table, it is advertised to BGP peers.
You can filter IGP routing information by routing protocols before the IGP routing
information is imported to BGP routing table.
Table 291 Import routes
Operation
Enter system view
Enable BGP, and enter BGP
view
Import and advertise routing
information generated by
other protocols.
Advertise network segment
routes to BGP routing table
CAUTION:
If a route is imported to the BGP routing table through the import-route
■
command, its Origin attribute is Incomplete.
The network segment route to be advertised must be in the local IP routing
■
table. You can use routing policy to control route advertising with more
flexibility.
The Origin attribute of the network segment routes advertised to BGP routing
■
table through the network command is IGP.
In a medium-/large-sized BGP network, you can reduce the number of the routes
to be advertised to BGP peers through route aggregation to save the spaces of
BGP peer routing tables. BGP supports two route aggregation modes: automatic
aggregation mode and manual aggregation mode.
Automatic aggregation mode, where IGP sub-network routes imported by BGP
■
are aggregated. In this mode, only the aggregated routes are advertised. The
imported IGP sub-network routes are not advertised. Note that the default
routes and the routes imported by using the network command cannot be
automatically aggregated.
Manual aggregation mode, where local BGP routes are aggregated. The
■
priority of manual aggregation is higher than that of automatic aggregation.
Command
system-view
bgp as-number
import-route protocol
[ process-id ] [ med
med-value | route-policy
route-policy-name ]*
network network-address
[ mask ] [ route-policy
route-policy-name ]
357
Description
-
Required
By default, BGP is disabled.
Required
By default, BGP does not
import nor advertise the
routing information generated
by other protocols.
Optional
By default, BGP does not
advertise any network segment
routes. Optional
By default, BGP does not
advertise any network segment
routes. Optional
By default, BGP does not
advertise any network segment
routes.