CCNP / BSCI Examination Tutorial: Route Summarization And also the OSPF Null Interface
CCNP Test achievements, specifically to the BSCI exam, calls for you recognize the main points of route summarization. This skill not only involves that you have a ease and comfort level with binary conversions, but You will need to know the way and where by to apply route summarization with Every single specific protocol.
You also have to grasp the “Unintended effects” of route summarization. With OSPF, there will essentially be an extra interface made at The purpose of summarization, which catches a lot of CCNP candidates abruptly. Let’s Have a look at the null0 interface And just how it pertains to OSPF summarization.
On R1, the subsequent networks are redistributed into OSPF, after which you can summarized.
interface Loopback16
ip tackle 16.sixteen.sixteen.16 255.0.0.0
interface Loopback17
ip handle 17.17.17.17 255.0.0.0
interface Loopback18
ip handle 18.eighteen.18.eighteen 255.0.0.0
interface Loopback19
ip tackle 19.19.19.19 255.0.0.0
R1(config)#router ospf one
R1(config-router)#redistribute connected subnets
R1(config-router)#summary-address sixteen.0.0.0 252.0.0.0
The summary deal with seems on R2, a downstream router.
R2#clearly show ip route ospf
O E2 sixteen.0.0.0/6 [a hundred and ten/twenty] via 172.twelve.123.one, 00:00:05, Serial0
Permit’s go back to R1 and check out its OSPF desk.
R1#display ip route ospf
O 16.0.0.0/6 can be a summary, 00:01:fifty one, Null0
Exactly where did the null0 interface originate from, and why can it be there? Packets sent to your null interface are dropped, and In such cases, that’s a good point.
Any time you configure summary routes in OSPF, a route to null0 will likely be put in in the OSPF 토토사이트 routing desk. This allows to forestall routing loops. Any packets destined for that routes that have been summarized will likely have an extended match while in the routing desk, as proven beneath…
C seventeen.0.0.0/eight is specifically related, Loopback17
C sixteen.0.0.0/8 is straight linked, Loopback16
C 19.0.0.0/8 is immediately related, Loopback19
C 18.0.0.0/8 is right connected, Loopback18
O 16.0.0.0/six can be a summary, 00:01:51, Null0
.. and packets that don't match one of many summarized routes but do match the summary route will probably be dropped.
Preventing routing loops when executing route redistribution and summarization is significant. OSPF gives us just a little help in that regard in this situation, and when you study a lot more complicated redistribution eventualities on your own solution to the CCNP and CCIE, you’ll realize that we’ll get all the assistance we might get!