CCNP / BSCI Test Tutorial: Route Summarization As well as OSPF Null Interface
CCNP Examination good results, specifically within the BSCI exam, demands you realize the main points of route summarization. This skill don't just needs that you have a comfort level with binary conversions, but You will need to know the way and wherever to use route summarization with Every single unique protocol.
You also have to learn the “Uncomfortable side effects” of route summarization. With OSPF, there'll really be an extra interface established at The purpose of 먹튀 summarization, and this catches plenty of CCNP candidates by surprise. Allow’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, and then summarized.
interface Loopback16
ip tackle 16.16.16.sixteen 255.0.0.0
interface Loopback17
ip address seventeen.17.17.17 255.0.0.0
interface Loopback18
ip address 18.eighteen.eighteen.18 255.0.0.0
interface Loopback19
ip address 19.19.19.19 255.0.0.0
R1(config)#router ospf 1
R1(config-router)#redistribute linked subnets
R1(config-router)#summary-handle sixteen.0.0.0 252.0.0.0
The summary deal with appears on R2, a downstream router.
R2#clearly show ip route ospf
O E2 16.0.0.0/six [110/twenty] by means of 172.12.123.one, 00:00:05, Serial0
Allow’s go back to R1 and check out its OSPF desk.
R1#show ip route ospf
O 16.0.0.0/6 is actually a summary, 00:01:51, Null0
In which did the null0 interface originate from, and why can it be there? Packets sent to the null interface are dropped, and In such a case, that’s a great issue.
If you configure summary routes in OSPF, a path to null0 will be set up into the OSPF routing desk. This helps to forestall routing loops. Any packets destined to the routes that have been summarized should have an extended match while in the routing table, as shown below…
C seventeen.0.0.0/eight is instantly linked, Loopback17
C 16.0.0.0/eight is specifically related, Loopback16
C 19.0.0.0/eight is straight linked, Loopback19
C eighteen.0.0.0/eight is directly related, Loopback18
O 16.0.0.0/6 is often a summary, 00:01:51, Null0
.. and packets that don't match one of the summarized routes but do match the summary route will probably be dropped.
Stopping routing loops when carrying out route redistribution and summarization is significant. OSPF gives us somewhat help in that regard in this case, and while you review more intricate redistribution eventualities with your method to the CCNP and CCIE, you’ll know that we’ll just take all the help we could possibly get!