CCNP / BSCI Exam Tutorial: Route Summarization And also the OSPF Null Interface
CCNP exam success, specially over the BSCI Test, needs you understand the main points of route summarization. This skill not only calls for that you've got a ease and comfort stage with binary conversions, but You need to understand how and the place to apply route summarization with Every single particular person protocol.
You even have to find out the “Unintended effects” of route summarization. With OSPF, there'll in fact be an additional interface created at The purpose of summarization, and this catches loads of CCNP candidates abruptly. Permit’s Consider the null0 interface And the way it relates to OSPF summarization.
On R1, the subsequent networks are redistributed into OSPF, after which you can summarized.
interface Loopback16
ip address 16.16.16.sixteen 255.0.0.0
interface Loopback17
ip handle 17.17.seventeen.17 255.0.0.0
interface Loopback18
ip deal with 18.eighteen.18.eighteen 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 connected subnets
R1(config-router)#summary-handle 16.0.0.0 252.0.0.0
The summary handle appears on R2, a downstream router.
R2#present ip route ospf
O E2 16.0.0.0/six [one hundred ten/20] via 172.twelve.123.one, 00:00:05, Serial0
Enable’s return to R1 and have a look at its OSPF desk.
R1#present ip route ospf
O 16.0.0.0/6 can be a summary, 00:01:51, Null0
The place did the null0 interface originate from, and why could it be there? Packets despatched towards the null interface are dropped, and In cases like this, that’s an excellent factor.
Once you configure summary routes in OSPF, a route to null0 will probably be set up into the OSPF routing table. This will help to prevent routing loops. Any packets destined with the routes which were summarized will have an extended match in the routing desk, as shown under…
C 17.0.0.0/8 is instantly linked, Loopback17
C 16.0.0.0/8 is right related, Loopback16
C 19.0.0.0/8 is instantly connected, Loopback19
C eighteen.0.0.0/8 is right connected, Loopback18
O sixteen.0.0.0/6 is 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 probably be dropped.
Protecting against routing loops when carrying out route redistribution and summarization is vital. OSPF provides us just a little help in that regard in this case, and as you research extra sophisticated redistribution eventualities with your solution to the CCNP and CCIE, you’ll recognize 먹튀검증 that we’ll choose all the assistance we could get!