CCNP / BSCI Examination Tutorial: Route Summarization And also the OSPF Null Interface
CCNP Examination good results, especially about the BSCI exam, calls for you comprehend the small print of route summarization. This skill don't just requires you have a comfort degree with binary conversions, but It's important to know how and wherever to use route summarization with Each individual specific protocol.
You even have to know the “Uncomfortable side effects” of route summarization. With OSPF, there'll really be an additional interface produced at the point of summarization, which catches loads of CCNP candidates without warning. Let’s Have a look at the null0 interface And the way it pertains to OSPF summarization.
On R1, the subsequent networks are redistributed into OSPF, and then summarized.
interface Loopback16
ip 토토사이트 address 16.16.16.16 255.0.0.0
interface Loopback17
ip handle seventeen.17.seventeen.17 255.0.0.0
interface Loopback18
ip address eighteen.18.eighteen.18 255.0.0.0
interface Loopback19
ip deal with 19.19.19.19 255.0.0.0
R1(config)#router ospf one
R1(config-router)#redistribute linked subnets
R1(config-router)#summary-deal with sixteen.0.0.0 252.0.0.0
The summary deal with appears on R2, a downstream router.
R2#present ip route ospf
O E2 16.0.0.0/6 [a hundred and ten/20] by way of 172.twelve.123.1, 00:00:05, Serial0
Enable’s return to R1 and check out its OSPF table.
R1#exhibit ip route ospf
O 16.0.0.0/six is actually a summary, 00:01:51, Null0
Exactly where did the null0 interface come from, and why could it be there? Packets despatched into the null interface are dropped, and In such a case, that’s a great thing.
Whenever you configure summary routes in OSPF, a route to null0 are going to be set up into your OSPF routing table. This assists to forestall routing loops. Any packets destined with the routes that have been summarized should have an extended match inside the routing desk, as proven under…
C 17.0.0.0/8 is specifically connected, Loopback17
C 16.0.0.0/eight is directly linked, Loopback16
C 19.0.0.0/8 is straight connected, Loopback19
C eighteen.0.0.0/eight is right linked, Loopback18
O 16.0.0.0/6 is often a summary, 00:01:51, Null0
.. and packets that do not match among the list of summarized routes but do match the summary route might be dropped.
Blocking routing loops when performing route redistribution and summarization is important. OSPF provides us a little bit help in that regard in this example, and when you study additional advanced redistribution eventualities with your technique to the CCNP and CCIE, you’ll realize that we’ll consider all the assistance we could get!