CCNP / BSCI Examination Tutorial: Route Summarization Along with the OSPF Null Interface
CCNP Examination achievement, specifically to the BSCI Test, demands you have an understanding of the main points of route summarization. This skill not just calls for you have a comfort and ease amount with binary conversions, 먹튀 but You should understand how and in which to use route summarization with Each individual person protocol.
You even have to be aware of the “Uncomfortable side effects” of route summarization. With OSPF, there'll basically be an extra interface made at The purpose of summarization, and this catches a great deal of CCNP candidates without warning. Allow’s Consider the null0 interface And the way it relates to OSPF summarization.
On R1, the following networks are redistributed into OSPF, and after that summarized.
interface Loopback16
ip address sixteen.16.16.16 255.0.0.0
interface Loopback17
ip deal with 17.seventeen.seventeen.seventeen 255.0.0.0
interface Loopback18
ip handle 18.18.18.eighteen 255.0.0.0
interface Loopback19
ip deal with 19.19.19.19 255.0.0.0
R1(config)#router ospf 1
R1(config-router)#redistribute connected subnets
R1(config-router)#summary-tackle 16.0.0.0 252.0.0.0
The summary tackle seems on R2, a downstream router.
R2#display ip route ospf
O E2 16.0.0.0/6 [one hundred ten/twenty] by means of 172.12.123.one, 00:00:05, Serial0
Allow’s go back to R1 and check out its OSPF table.
R1#display ip route ospf
O sixteen.0.0.0/six is really a summary, 00:01:51, Null0
Exactly where did the null0 interface originate from, and why is it there? Packets sent into the null interface are dropped, and In such a case, that’s an excellent point.
If you configure summary routes in OSPF, a route to null0 are going to be put in in to the OSPF routing desk. This will help to avoid routing loops. Any packets destined for your routes which were summarized should have an extended match during the routing desk, as proven beneath…
C seventeen.0.0.0/8 is right linked, Loopback17
C sixteen.0.0.0/eight is instantly related, Loopback16
C 19.0.0.0/8 is specifically linked, Loopback19
C eighteen.0.0.0/8 is specifically linked, Loopback18
O sixteen.0.0.0/six is usually a summary, 00:01:51, Null0
.. and packets that don't match among the summarized routes but do match the summary route will likely be dropped.
Blocking routing loops when doing route redistribution and summarization is vital. OSPF offers us a little help in that regard in this case, and while you research far more sophisticated redistribution eventualities in your technique to the CCNP and CCIE, you’ll realize that we’ll take all the assistance we will get!