Cisco CCNP / BSCI Exam Tutorial: Using OSPF’s “Summary-Address” Command
BSCI exam success, not to mention earning your CCNP, can come down to your OSPF route summarization skills. There are a few different commands and situations you need to be ready for, and one of these situations is the proper use of the “summary-address” command.
The summary-address command should be used on an ASBR in order to summarize routes that are being injected into the OSPF domain via redistribution. In the following example, four routes are being redisitributed into OSPF on R1, making R1 an ASBR.
interface Loopback16
ip address 16.16.16.16 255.0.0.0
!
interface Loopback17
ip address 17.17.17.17 255.0.0.0
!
interface Loopback18
ip address 18.18.18.18 255.0.0.0
!
interface Loopback19
ip address 19.19.19.19 255.0.0.0
R1(config)#router ospf 1
R1(config-router)#redistribute connected subnets
These four routes are seen on downstream router R2 as External Type-2, the default for routes redistributed into OSPF.
R2#show ip route ospf
O E2 17.0.0.0/8...