CCNP / BSCI Exam Tutorial: Route Summarization Along with the OSPF Null Interface
CCNP Test accomplishment, significantly within the BSCI Examination, demands you realize the details of route summarization. This ability not just needs you have a comfort and ease stage with binary conversions, but It's important to know how and exactly where to use route summarization with Each and every personal protocol.
You even have to grasp the “Unwanted side effects” of route summarization. With OSPF, there'll really be an additional interface established at The purpose of summarization, and this catches many CCNP candidates unexpectedly. Enable’s Have a look at the null0 interface And just how it pertains to OSPF summarization.
On R1, the next networks are redistributed into OSPF, and then summarized.
interface Loopback16
ip address sixteen.sixteen.sixteen.16 255.0.0.0
interface Loopback17
ip handle seventeen.seventeen.17.seventeen 255.0.0.0
interface Loopback18
ip address eighteen.eighteen.eighteen.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 linked subnets
R1(config-router)#summary-address 16.0.0.0 252.0.0.0
The summary address appears on R2, a downstream router.
R2#demonstrate ip route ospf
O E2 16.0.0.0/six [110/twenty] by using 172.twelve.123.1, 00:00:05, Serial0
Let’s return to R1 and examine its OSPF table.
R1#display ip route ospf
O sixteen.0.0.0/six can be a summary, 00:01:51, Null0
Where by did the null0 interface originate from, and why is it there? Packets sent towards the null interface are dropped, and In such cases, that’s a very good point.
After you configure summary routes in OSPF, a path to null0 is going to be put in into your OSPF routing desk. This helps to circumvent routing loops. Any packets destined with the routes which have been summarized can have a longer match within the routing table, as revealed down below…
C seventeen.0.0.0/8 is right linked, Loopback17
C sixteen.0.0.0/eight is instantly linked, Loopback16
C 19.0.0.0/8 is straight connected, Loopback19
C eighteen.0.0.0/eight is directly linked, Loopback18
O sixteen.0.0.0/six is often a summary, 00:01:fifty one, Null0
.. and packets that do not match one of the summarized routes but do match the summary route might be dropped.
Stopping routing loops when accomplishing route redistribution and summarization is important. OSPF gives us a bit assist in that regard in this situation, 먹튀 and while you study additional advanced redistribution situations on your technique to the CCNP and CCIE, you’ll realize that we’ll get all the assistance we could get!