CCNP / BSCI Test Tutorial: Route Summarization As well as OSPF Null Interface
CCNP exam results, specially to the BSCI Test, requires you recognize the details of route summarization. This skill not merely requires that you've a comfort and ease amount with binary conversions, but You must know how and wherever to apply route summarization with Each and every unique protocol.
You even have to find out the “Unwanted effects” of route summarization. With OSPF, there will essentially be an additional interface created at the point of summarization, which catches a lot of CCNP candidates abruptly. Enable’s Look into the null0 interface And exactly how it pertains to OSPF summarization.
On R1, the following networks are redistributed into OSPF, then summarized.
interface Loopback16
ip address sixteen.16.16.sixteen 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 address 19.19.19.19 255.0.0.0
R1(config)#router ospf one
R1(config-router)#redistribute connected subnets
R1(config-router)#summary-tackle 16.0.0.0 252.0.0.0
The summary tackle seems on R2, a downstream router.
R2#show ip route ospf
O E2 sixteen.0.0.0/6 [one hundred ten/20] through 172.12.123.one, 00:00:05, Serial0
Enable’s go back to R1 and take a look at its OSPF desk.
R1#exhibit ip route ospf
O sixteen.0.0.0/6 is often a summary, 00:01:fifty one, Null0
Wherever did the null0 interface come from, and why can it be there? Packets despatched for the null interface are dropped, and in this case, that’s an excellent factor.
Any time you configure summary routes in OSPF, a route to null0 might be put in to the OSPF routing table. This helps to circumvent routing loops. Any packets destined for the routes which were summarized may have an extended match inside the routing desk, as revealed below…
C seventeen.0.0.0/eight is right related, Loopback17
C 16.0.0.0/eight is directly related, Loopback16
C 19.0.0.0/8 is right related, Loopback19
C eighteen.0.0.0/eight is immediately related, Loopback18
O sixteen.0.0.0/six is really a summary, 00:01:51, Null0
.. and packets that do not match one of several summarized 토토사이트 routes but do match the summary route will be dropped.
Avoiding routing loops when carrying out route redistribution and summarization is vital. OSPF offers us slightly assist in that regard in this situation, and when you examine extra sophisticated redistribution eventualities on your technique to the CCNP and CCIE, you’ll understand that we’ll just take all the help we can get!