CCNP / BSCI Examination Tutorial: Route Summarization And also the OSPF Null Interface
CCNP Examination accomplishment, notably on the BSCI exam, demands you recognize the details of route summarization. This talent not only necessitates that you've got a comfort and ease amount with binary conversions, but It's important to know how and where by to use route summarization with Just about every specific protocol.
You also have to know the “Negative effects” of route summarization. With OSPF, there will really be an extra interface produced at The purpose of summarization, which catches plenty of CCNP candidates abruptly. Allow’s Consider the null0 interface And just how it pertains to OSPF summarization.
On R1, the following networks are redistributed into OSPF, after which you can summarized.
interface Loopback16
ip handle 16.sixteen.16.16 255.0.0.0
interface Loopback17
ip deal with 17.17.seventeen.17 255.0.0.0
interface Loopback18
ip tackle eighteen.eighteen.18.eighteen 255.0.0.0
interface Loopback19
ip tackle 19.19.19.19 255.0.0.0
R1(config)#router ospf one
R1(config-router)#redistribute related subnets
R1(config-router)#summary-tackle 16.0.0.0 252.0.0.0
The summary deal with seems on R2, a downstream router.
R2#display ip route ospf
O E2 sixteen.0.0.0/six [one hundred ten/twenty] via 172.12.123.one, 00:00:05, Serial0
Let’s return to R1 and examine its OSPF table.
R1#show ip route ospf
O 16.0.0.0/six can be a summary, 00:01:51, Null0
Wherever did the null0 interface come from, and why can it be there? Packets despatched to your null interface are dropped, and In such cases, that’s a good thing.
When you configure summary routes in OSPF, a route to null0 are going to be installed in the OSPF routing table. This assists to avoid routing loops. Any packets destined for the routes which have been summarized will have a longer match while in the routing desk, as shown underneath…
C seventeen.0.0.0/8 is specifically linked, Loopback17
C 16.0.0.0/8 is straight related, Loopback16
C 19.0.0.0/8 is right related, Loopback19
C eighteen.0.0.0/8 is directly linked, Loopback18
O 16.0.0.0/six is actually a summary, 00:01:51, Null0
.. and packets that don't match one of several summarized routes but do match the summary route might be dropped.
Avoiding routing loops when executing route redistribution and summarization is vital. OSPF offers us a little bit help in that regard in this example, and as you 토토사이트 review additional complex redistribution scenarios on the technique to the CCNP and CCIE, you’ll know that we’ll acquire all the assistance we will get!