Route Confederations - Extreme Networks ExtremeWare XOS Guide Manual

To configure router 4.4.4.4, use the following commands:
create vlan to_rr
configure vlan to_rr add port 1:1
configure vlan to_rr ipaddress 30.0.0.1/24
enable ipforwarding vlan to_rr
configure bgp router 4.4.4.4
configure bgp as-number 100
create bgp neighbor 30.0.0.2 remote-as 100
enable bgp neighbor all
enable bgp

Route Confederations

BGP requires networks to use a fully meshed router configuration. This requirement does not scale well,
especially when BGP is used as an IGP. One way to reduce the size of a fully meshed AS is to divide the
AS into multiple sub-ASs and to group these sub-ASs into a routing confederation. Within the
confederation, each sub-AS must be fully meshed. The confederation is advertised to other networks as
a single AS.
Route Confederation Example
Figure 64 shows an example of a confederation.
Figure 64: Routing confederation
AS 200
A
EBGP
192.1.1.17/30
192.1.1.18/30
EBGP
E
In this example, AS 200 has five BGP speakers. Without a confederation, BGP would require that the
routes in AS 200 be fully meshed. Using the confederation, AS 200 is split into two sub-ASs: AS65001
and AS65002. Each sub-AS is fully meshed, and IBGP is running among its members. EBGP is used
ExtremeWare XOS 11.1 Concepts Guide
SubAS 65001
192.1.1.6/30 192.1.1.5/30
IBGP
192.1.1.21/30
C
192.1.1.13/30 192.1.1.14/30
IBGP
SubAS 65002
B
192.1.1.9/30
192.1.1.22/30
EBGP
192.1.1.10/30
D
BGP Features
EX_043
401