CCNP / BSCI Test Tutorial: Route Summarization As well as the OSPF Null Interface
CCNP exam success, specially around the BSCI exam, demands you realize the details of route summarization. This ability not just requires that you have a comfort amount with binary conversions, but It's important to know the way and where to apply route summarization with Every 토토 particular person protocol.
You even have to grasp the “Unintended effects” of route summarization. With OSPF, there will truly be an extra interface created at The purpose of summarization, which catches lots of CCNP candidates by surprise. Let’s Examine the null0 interface And the way it relates to OSPF summarization.
On R1, the following networks are redistributed into OSPF, then summarized.
interface Loopback16
ip handle 16.16.sixteen.sixteen 255.0.0.0
interface Loopback17
ip deal with 17.17.seventeen.seventeen 255.0.0.0
interface Loopback18
ip deal with eighteen.eighteen.18.18 255.0.0.0
interface Loopback19
ip tackle 19.19.19.19 255.0.0.0
R1(config)#router ospf 1
R1(config-router)#redistribute linked subnets
R1(config-router)#summary-deal with 16.0.0.0 252.0.0.0
The summary tackle seems on R2, a downstream router.
R2#show ip route ospf
O E2 16.0.0.0/six [110/20] by way of 172.twelve.123.1, 00:00:05, Serial0
Permit’s return to R1 and examine its OSPF table.
R1#show ip route ospf
O sixteen.0.0.0/six is usually a summary, 00:01:51, Null0
In which did the null0 interface originate from, and why can it be there? Packets despatched for the null interface are dropped, and In cases like this, that’s a very good thing.
After you configure summary routes in OSPF, a path to null0 is going to be put in into your OSPF routing desk. This assists to circumvent routing loops. Any packets destined for the routes which have been summarized may have a longer match within the routing table, as revealed beneath…
C 17.0.0.0/8 is specifically linked, Loopback17
C sixteen.0.0.0/8 is immediately related, Loopback16
C 19.0.0.0/8 is directly related, Loopback19
C 18.0.0.0/eight is straight related, Loopback18
O sixteen.0.0.0/six is really a summary, 00:01:51, Null0
.. and packets that do not match among the summarized routes but do match the summary route might be dropped.
Protecting against routing loops when performing route redistribution and summarization is vital. OSPF provides us a little help in that regard in this case, and while you study much more advanced redistribution eventualities on your approach to the CCNP and CCIE, you’ll know that we’ll get all the assistance we will get!