CCNP / BSCI Examination Tutorial: Route Summarization Plus the OSPF Null Interface
CCNP Test results, specifically around the BSCI Test, demands you understand the main points of route summarization. This skill not only involves you have a consolation level with binary conversions, but you have to know the way and the place to apply route summarization with Each individual unique protocol.
You also have to know the “Unintended effects” of route summarization. With OSPF, there'll in fact be an additional interface produced at The purpose of summarization, which catches lots of CCNP candidates by surprise. Let’s Consider the null0 interface and how it pertains to OSPF 먹튀 summarization.
On R1, the following networks are redistributed into OSPF, after which you can summarized.
interface Loopback16
ip tackle sixteen.16.16.sixteen 255.0.0.0
interface Loopback17
ip deal with 17.seventeen.17.seventeen 255.0.0.0
interface Loopback18
ip tackle 18.18.eighteen.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 linked subnets
R1(config-router)#summary-tackle sixteen.0.0.0 252.0.0.0
The summary handle seems on R2, a downstream router.
R2#display ip route ospf
O E2 sixteen.0.0.0/6 [110/twenty] via 172.twelve.123.one, 00:00:05, Serial0
Enable’s go back to R1 and look at its OSPF desk.
R1#show ip route ospf
O sixteen.0.0.0/6 is often a summary, 00:01:fifty one, Null0
Wherever did the null0 interface originate from, and why can it be there? Packets sent to your null interface are dropped, and In cases like this, that’s a superb point.
Once you configure summary routes in OSPF, a route to null0 is going to be installed in the OSPF routing desk. This assists to prevent routing loops. Any packets destined with the routes which have been summarized could have an extended match while in the routing desk, as shown below…
C 17.0.0.0/8 is straight connected, Loopback17
C 16.0.0.0/eight is directly connected, Loopback16
C 19.0.0.0/8 is specifically related, Loopback19
C eighteen.0.0.0/eight is right linked, Loopback18
O 16.0.0.0/six can be a summary, 00:01:51, Null0
.. and packets that don't match one of the summarized routes but do match the summary route is going to be dropped.
Preventing routing loops when doing route redistribution and summarization is significant. OSPF offers us a bit help in that regard in this example, and when you study much more elaborate redistribution eventualities on your own technique to the CCNP and CCIE, you’ll understand that we’ll just take all the help we may get!