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Router B and Router D are in the same confederation, but belong to different sub-ASs. They obtain
external route information from Router A and generate identical BGP route entries although they
have no direct connection in between.
BGP path selection configuration example
Network requirements
As shown in
, all routers run BGP. EBGP runs between Router A and Router B, and between
Router A and Router C. IBGP runs between Router B and Router D, and between Router D and Router C.
OSPF is the IGP protocol in AS 200.
Configure routing policies to make Router D give priority to the route 1.0.0.0/8 learned from Router C.
Figure 69
Network diagram
Device Interface
IP
address
Device
Interface IP
address
Router A
Eth1/1
1.0.0.1/8
Router D
Eth1/1 195.1.1.1/24
Eth1/2
192.1.1.1/24
Eth1/2
194.1.1.1/24
Eth1/3
193.1.1.1/24
Router C
Eth1/1 193.1.1.2/24
Router B
Eth1/1
192.1.1.2/24
Eth1/2 195.1.1.2/24
Eth1/2
194.1.1.2/24
Configuration procedure
1.
Configure IP addresses for interfaces. (Details not shown.)
2.
Configure OSPF on Router B, Router C, and Router D:
# Configure Router B.
<RouterB> system-view
[RouterB] ospf
[RouterB-ospf] area 0
[RouterB-ospf-1-area-0.0.0.0] network 192.1.1.0 0.0.0.255
[RouterB-ospf-1-area-0.0.0.0] network 194.1.1.0 0.0.0.255
[RouterB-ospf-1-area-0.0.0.0] quit
[RouterB-ospf-1] quit
# Configure Router C.
<RouterC> system-view
[RouterC] ospf
[RouterC-ospf] area 0
[RouterC-ospf-1-area-0.0.0.0] network 193.1.1.0 0.0.0.255