CCNP / BSCI Test Tutorial: Route Summarization As well as OSPF Null Interface
CCNP exam achievement, particularly over the BSCI Test, needs you comprehend the small print of route summarization. This skill don't just necessitates that you've got a ease and comfort level with binary conversions, but You need to know how and the place to use route summarization 먹튀 with each personal protocol.
You also have to know the “Unintended effects” of route summarization. With OSPF, there will really be an additional interface designed at the point of summarization, which catches a great deal of CCNP candidates by surprise. Allow’s Check out the null0 interface and how it pertains to OSPF summarization.
On R1, the next networks are redistributed into OSPF, after which you can summarized.
interface Loopback16
ip deal with 16.sixteen.16.sixteen 255.0.0.0
interface Loopback17
ip handle 17.17.17.17 255.0.0.0
interface Loopback18
ip tackle eighteen.eighteen.eighteen.18 255.0.0.0
interface Loopback19
ip deal with 19.19.19.19 255.0.0.0
R1(config)#router ospf 1
R1(config-router)#redistribute related subnets
R1(config-router)#summary-address 16.0.0.0 252.0.0.0
The summary address seems on R2, a downstream router.
R2#clearly show ip route ospf
O E2 sixteen.0.0.0/six [a hundred and ten/twenty] by using 172.twelve.123.1, 00:00:05, Serial0
Let’s return to R1 and check out its OSPF table.
R1#display ip route ospf
O 16.0.0.0/6 is a summary, 00:01:fifty one, Null0
Exactly where did the null0 interface originate from, and why can it be there? Packets sent on the null interface are dropped, and in this case, that’s a superb factor.
After you configure summary routes in OSPF, a route to null0 are going to be mounted in to the OSPF routing table. This assists to circumvent routing loops. Any packets destined with the routes which have been summarized will have an extended match from the routing table, as proven underneath…
C seventeen.0.0.0/8 is instantly connected, Loopback17
C 16.0.0.0/8 is specifically connected, Loopback16
C 19.0.0.0/8 is straight related, Loopback19
C eighteen.0.0.0/8 is right linked, Loopback18
O sixteen.0.0.0/6 is actually a summary, 00:01:fifty one, Null0
.. and packets that don't match among the list of summarized routes but do match the summary route will likely be dropped.
Blocking routing loops when carrying out route redistribution and summarization is important. OSPF provides us just a little assist in that regard in this situation, and while you review extra complicated redistribution eventualities on your method to the CCNP and CCIE, you’ll realize that we’ll get all the help we may get!