CCNP / BSCI Exam Tutorial: Route Summarization And also the OSPF Null Interface
CCNP Examination results, significantly within the BSCI Test, needs you comprehend the details of route summarization. This talent not only demands that you've got a comfort and ease degree with binary conversions, but you have to know the way and exactly where to apply route summarization with Each and every personal protocol.
You also have to find out the “Unwanted side effects” of route summarization. With OSPF, there'll in fact be an additional interface designed at the point of summarization, which catches a lot of CCNP candidates unexpectedly. Permit’s Look into the null0 interface And just how it relates to OSPF summarization.
On R1, the next networks are redistributed into OSPF, after which you can summarized.
interface Loopback16
ip deal with sixteen.sixteen.16.16 255.0.0.0
interface Loopback17
ip address seventeen.17.17.seventeen 255.0.0.0
interface Loopback18
ip handle eighteen.18.eighteen.18 255.0.0.0
interface Loopback19
ip handle 19.19.19.19 255.0.0.0
R1(config)#router ospf one
R1(config-router)#redistribute related subnets
R1(config-router)#summary-handle 16.0.0.0 252.0.0.0
The summary address seems on R2, a downstream router.
R2#present ip route ospf
O E2 sixteen.0.0.0/six [one hundred ten/twenty] by means of 172.twelve.123.one, 00:00:05, Serial0
Let’s return to R1 and have a look at its OSPF table.
R1#clearly show ip route ospf
O 16.0.0.0/six is a summary, 00:01:51, Null0
The place did the null0 interface come from, and why can it be there? Packets sent to your null interface are dropped, and In such cases, that’s a very good thing.
Once you configure summary routes in OSPF, a route to null0 might be mounted in the OSPF routing desk. This allows to circumvent routing loops. Any packets destined to the routes which have been summarized will have an extended match while in the routing table, as shown under…
C 17.0.0.0/eight is instantly related, Loopback17
C 16.0.0.0/eight is directly linked, Loopback16
C 19.0.0.0/eight is immediately connected, Loopback19
C eighteen.0.0.0/8 is right linked, Loopback18
O sixteen.0.0.0/six is actually a summary, 00:01:51, Null0
.. and packets that don't match on the list of summarized routes but do match the summary route are going to 먹튀검증 be dropped.
Stopping routing loops when carrying out route redistribution and summarization is important. OSPF gives us just a little assist in that regard in this case, and while you analyze a lot more complicated redistribution scenarios on your way to the CCNP and CCIE, you’ll know that we’ll choose all the assistance we may get!