CCNP / BSCI Exam Tutorial: Route Summarization Along with the OSPF Null Interface
CCNP Test achievements, notably around the BSCI Examination, demands you realize the main points of route summarization. This talent not only necessitates that you have a comfort and ease amount with binary conversions, but You will need to know the way and in which to apply route summarization with Each and every unique protocol.
You even have to grasp the “Negative effects” of route summarization. With OSPF, there will in fact be an extra interface produced at the point of summarization, and this catches many CCNP candidates without warning. Enable’s Check out the null0 interface and how it relates to OSPF summarization.
On R1, the following networks are redistributed into OSPF, and then summarized.
interface Loopback16
ip deal with 16.sixteen.sixteen.16 255.0.0.0
interface Loopback17
ip tackle seventeen.17.17.17 255.0.0.0
interface Loopback18
ip handle eighteen.eighteen.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 related subnets
R1(config-router)#summary-tackle sixteen.0.0.0 252.0.0.0
The summary tackle seems on R2, a downstream router.
R2#display ip route ospf
O E2 sixteen.0.0.0/6 [a hundred and ten/20] by way of 172.12.123.one, 00:00:05, Serial0
Permit’s return to R1 and examine its OSPF desk.
R1#show ip route ospf
O 16.0.0.0/six is actually a summary, 00:01:51, Null0
In which did the null0 interface come from, and why can it be there? Packets sent to your null interface are dropped, and In 먹튀 this instance, that’s a superb factor.
If you configure summary routes in OSPF, a route to null0 are going to be mounted into the OSPF routing desk. This will help to avoid routing loops. Any packets destined for that routes that have been summarized should have a longer match within the routing table, as demonstrated below…
C 17.0.0.0/eight is straight connected, Loopback17
C 16.0.0.0/eight is straight connected, Loopback16
C 19.0.0.0/8 is right connected, Loopback19
C 18.0.0.0/eight is immediately linked, Loopback18
O sixteen.0.0.0/six can be a summary, 00:01:51, Null0
.. and packets that don't match one of the summarized routes but do match the summary route will be dropped.
Avoiding routing loops when performing route redistribution and summarization is significant. OSPF gives us just a little assist in that regard in this case, and as you study more elaborate redistribution eventualities on your solution to the CCNP and CCIE, you’ll realize that we’ll get all the help we could possibly get!