CCNP / BSCI Test Tutorial: Route Summarization As well as OSPF Null Interface
CCNP Test good results, notably over the BSCI Test, needs you comprehend the main points of route summarization. This talent not just calls for you have a consolation stage with binary conversions, but You should know the way and where to apply route summarization with Each individual individual protocol.
You even have to grasp the “Unintended effects” of route summarization. With OSPF, there will actually be an extra interface created at the point of summarization, which catches a great deal of CCNP candidates without warning. Allow’s Have a look at the null0 interface and how it pertains to OSPF summarization.
On R1, the following networks are redistributed into 토토사이트 OSPF, after which you can summarized.
interface Loopback16
ip handle 16.16.16.sixteen 255.0.0.0
interface Loopback17
ip deal with 17.17.seventeen.seventeen 255.0.0.0
interface Loopback18
ip tackle eighteen.18.18.18 255.0.0.0
interface Loopback19
ip address 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 address seems on R2, a downstream router.
R2#demonstrate ip route ospf
O E2 16.0.0.0/six [110/20] by means of 172.12.123.1, 00:00:05, Serial0
Enable’s return to R1 and evaluate its OSPF desk.
R1#display ip route ospf
O 16.0.0.0/6 is usually a summary, 00:01:fifty one, Null0
The place did the null0 interface originate from, and why can it be there? Packets sent for the null interface are dropped, and In cases like this, that’s a very good point.
Whenever you configure summary routes in OSPF, a route to null0 will be put in in the OSPF routing desk. This will help to forestall routing loops. Any packets destined for the routes which were summarized may have a longer match while in the routing table, as demonstrated below…
C seventeen.0.0.0/eight is specifically linked, Loopback17
C 16.0.0.0/8 is directly related, Loopback16
C 19.0.0.0/eight is right linked, Loopback19
C eighteen.0.0.0/8 is right connected, Loopback18
O sixteen.0.0.0/six is often a summary, 00:01:51, Null0
.. and packets that do not match among the summarized routes but do match the summary route is going to be dropped.
Preventing routing loops when accomplishing route redistribution and summarization is important. OSPF provides us a bit assist in that regard in this situation, and while you study a lot more elaborate redistribution eventualities on your own strategy to the CCNP and CCIE, you’ll recognize that we’ll get all the help we will get!