CCNP / BSCI Test Tutorial: Route Summarization Plus the OSPF Null Interface
CCNP Test results, especially within the BSCI Test, calls for you realize the details of route summarization. This ability not simply requires that you've got a consolation level with binary conversions, but You should know the way and where by to apply route summarization with each person protocol.
You even have to learn the “Unwanted effects” of route summarization. With OSPF, there'll essentially be an extra interface developed at the point of summarization, which catches plenty of CCNP candidates unexpectedly. Let’s Look into the null0 interface And exactly how it pertains to OSPF summarization.
On R1, the next networks are redistributed into OSPF, and afterwards summarized.
interface Loopback16
ip deal with 16.sixteen.sixteen.16 255.0.0.0
interface Loopback17
ip deal with seventeen.17.seventeen.17 255.0.0.0
interface Loopback18
ip tackle eighteen.eighteen.18.eighteen 255.0.0.0
interface Loopback19
ip handle 19.19.19.19 255.0.0.0
R1(config)#router ospf one
R1(config-router)#redistribute connected subnets
R1(config-router)#summary-deal with 16.0.0.0 252.0.0.0
The summary tackle seems on R2, a downstream router.
R2#exhibit ip route ospf
O E2 16.0.0.0/6 [one hundred ten/twenty] by way of 172.12.123.1, 00:00:05, Serial0
Enable’s go back to R1 and examine its OSPF table.
R1#present ip route ospf
O sixteen.0.0.0/6 can be a summary, 00:01:51, Null0
Where by did the null0 interface originate from, and why is it there? Packets sent into the null interface are dropped, and In such cases, that’s an excellent detail.
After you configure summary routes in OSPF, a path to null0 will be mounted into your OSPF routing desk. This assists to stop routing loops. Any packets destined with the routes which were summarized could have a longer match during the routing table, as demonstrated beneath…
C 17.0.0.0/8 is straight connected, Loopback17
C sixteen.0.0.0/8 is specifically linked, Loopback16
C 19.0.0.0/8 is right linked, Loopback19
C eighteen.0.0.0/8 is immediately related, Loopback18
O 16.0.0.0/6 is actually a summary, 00:01:51, Null0
.. 토토 and packets that do not match one of the summarized routes but do match the summary route will be dropped.
Preventing routing loops when accomplishing route redistribution and summarization is vital. OSPF presents us somewhat help in that regard in this example, and while you review a lot more elaborate redistribution eventualities on the technique to the CCNP and CCIE, you’ll recognize that we’ll consider all the help we will get!