CCNP / BSCI Examination Tutorial: Route Summarization As well as the OSPF Null Interface
CCNP Test success, specifically over the BSCI Test, requires you comprehend the small print of route summarization. This ability not merely necessitates you have a consolation level with binary conversions, but You should know the way and wherever to use route summarization with Each individual unique protocol.
You also have to learn the “side effects” of route summarization. With OSPF, there'll in fact be an additional interface made at The purpose of summarization, which catches plenty of CCNP candidates without warning. Enable’s take a look at the null0 interface And exactly how it relates to OSPF summarization.
On R1, the subsequent networks are redistributed into OSPF, and then summarized.
interface Loopback16
ip address sixteen.16.16.sixteen 255.0.0.0
interface Loopback17
ip tackle 17.seventeen.seventeen.seventeen 255.0.0.0
interface Loopback18
ip deal with eighteen.eighteen.eighteen.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 appears on R2, a downstream router.
R2#display ip route ospf
O E2 16.0.0.0/six [a hundred and ten/twenty] by using 172.12.123.one, 00:00:05, Serial0
Enable’s go back to R1 and look at its OSPF desk.
R1#exhibit ip route ospf
O 16.0.0.0/six is usually a summary, 00:01:51, Null0
Where by did the null0 interface come from, and why can it be there? Packets despatched into the null interface are dropped, and In cases like this, that’s a good detail.
After you configure summary routes in OSPF, a path to null0 will likely be put in in the OSPF routing desk. This can help to avoid routing loops. Any packets destined for that routes which were summarized should have a longer match while in the routing desk, as shown underneath…
C seventeen.0.0.0/eight is straight linked, Loopback17
C sixteen.0.0.0/eight is right linked, Loopback16
C 19.0.0.0/eight is instantly linked, Loopback19
C 18.0.0.0/eight is immediately connected, Loopback18
O sixteen.0.0.0/6 is a summary, 00:01:51, Null0
.. and packets that don't match on the list of summarized routes but do match the summary route will be dropped.
Stopping routing loops when executing route redistribution and summarization is vital. OSPF provides us a little assist in that regard in this situation, and here while you review a lot more elaborate redistribution scenarios on the solution to the https://www.washingtonpost.com/newssearch/?query=토토사이트 CCNP and CCIE, you’ll realize that we’ll acquire all the help we will get!