CCNP / BSCI Examination Tutorial: Route Summarization Along with the OSPF Null Interface
CCNP exam achievement, specifically about the BSCI Examination, requires you recognize the details of route summarization. This ability not simply demands that you've a comfort amount with binary conversions, but You should know the way and exactly where to use route summarization with Every single specific protocol.
You also have to understand the “Unwanted effects” of route summarization. With OSPF, there'll really be an additional interface developed at the point of summarization, which catches a lot of CCNP candidates without warning. Enable’s Consider the null0 interface And the way it relates to OSPF summarization.
On R1, the following networks are redistributed into OSPF, after which summarized.
interface Loopback16
ip tackle 16.sixteen.16.sixteen 255.0.0.0
interface Loopback17
ip deal with seventeen.seventeen.seventeen.17 255.0.0.0
interface Loopback18
ip deal with 18.18.18.18 255.0.0.0
interface Loopback19
ip handle 19.19.19.19 255.0.0.0
R1(config)#router ospf 1
R1(config-router)#redistribute linked subnets
R1(config-router)#summary-address sixteen.0.0.0 252.0.0.0
The summary deal with appears on R2, a downstream router.
R2#exhibit ip route ospf
O E2 sixteen.0.0.0/6 [110/twenty] by using 172.12.123.1, 00:00:05, Serial0
Permit’s return to R1 and check out its OSPF table.
R1#demonstrate ip route ospf
O 16.0.0.0/six can be a summary, 00:01:51, Null0
Wherever did the null0 interface originate from, and why is it there? Packets sent to your null interface are dropped, and In such a case, that’s a very good matter.
When you configure summary routes in OSPF, a route to null0 are going to be mounted into your OSPF routing desk. This aids to circumvent routing loops. Any https://en.wikipedia.org/wiki/?search=토토사이트 packets destined to the routes which have been summarized will have an extended 토토 match from the routing desk, as revealed under…
C 17.0.0.0/8 is right related, Loopback17
C sixteen.0.0.0/eight is specifically related, Loopback16
C 19.0.0.0/eight is immediately linked, Loopback19
C eighteen.0.0.0/8 is instantly connected, Loopback18
O sixteen.0.0.0/6 is actually a summary, 00:01:51, Null0
.. and packets that do not match one of several summarized routes but do match the summary route is going to be dropped.
Protecting against routing loops when accomplishing route redistribution and summarization is important. OSPF provides us a little help in that regard in this example, and when you examine additional complex redistribution eventualities on your method to the CCNP and CCIE, you’ll understand that we’ll consider all the assistance we might get!