CCNP / BSCI Exam Tutorial: Route Summarization And also the OSPF Null Interface
CCNP Test achievement, specifically about the BSCI Test, needs you comprehend the small print of route summarization. This ability not merely necessitates that you have a ease and comfort amount with binary conversions, but You should know the way and exactly where to apply route summarization with Each and every particular person protocol.
You even have to be aware of the “Unintended effects” of route summarization. With OSPF, there will basically be an extra interface made at The purpose of summarization, and this catches loads of CCNP candidates unexpectedly. Enable’s take a look at the null0 interface And just how it relates to OSPF summarization.
On R1, the following networks are redistributed into OSPF, after which you can summarized.
interface Loopback16
ip deal with sixteen.sixteen.sixteen.16 255.0.0.0
interface Loopback17
ip address seventeen.seventeen.17.seventeen 255.0.0.0
interface Loopback18
ip handle 18.18.18.eighteen 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 linked subnets
R1(config-router)#summary-address 16.0.0.0 252.0.0.0
The summary address seems on R2, a downstream router.
R2#demonstrate ip route ospf
O E2 sixteen.0.0.0/six [one hundred ten/twenty] by using 172.12.123.one, 00:00:05, Serial0
Permit’s return to R1 and evaluate its OSPF desk.
R1#exhibit ip route ospf
O sixteen.0.0.0/six is a summary, 00:01:51, Null0
The place did the null0 interface come from, and why could it be there? Packets despatched towards the null interface are dropped, and In such cases, that’s a superb issue.
If you configure summary routes in OSPF, a path to null0 might be put in into the OSPF routing table. This can help to forestall routing loops. Any packets destined with the routes that were summarized will have a longer match in the routing desk, as demonstrated under…
C 17.0.0.0/8 is straight connected, Loopback17
C sixteen.0.0.0/eight is specifically connected, Loopback16
C 19.0.0.0/8 is right linked, Loopback19
C 18.0.0.0/eight is specifically linked, Loopback18
O sixteen.0.0.0/6 is often a summary, 00:01:51, Null0
.. and packets that do not match among the summarized routes but do match the summary route will probably be dropped.
Avoiding routing loops when undertaking route 먹튀검증 redistribution and summarization is vital. OSPF presents us a little bit assist in that regard in this example, and as you study extra intricate redistribution scenarios on the solution to the CCNP and CCIE, you’ll recognize that we’ll consider all the assistance we can get!