CCNP / BSCI Test Tutorial: Route Summarization Along with the OSPF Null Interface
CCNP Test achievement, specially within the BSCI Test, requires you recognize the small print of route summarization. This talent not simply needs that you've got a consolation level with binary conversions, but You must know the way and the place to use route summarization with Every particular person protocol.
You even have to understand the “Unwanted side effects” of route summarization. With OSPF, there will basically be an extra interface created at The purpose of summarization, which catches plenty of CCNP candidates by surprise. Let’s take a look at the null0 interface And the way it relates to OSPF summarization.
On R1, the following networks are redistributed into OSPF, then summarized.
interface Loopback16
ip deal with 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 handle 19.19.19.19 255.0.0.0
R1(config)#router ospf 1
R1(config-router)#redistribute related subnets
R1(config-router)#summary-tackle 16.0.0.0 252.0.0.0
The summary handle appears on R2, a downstream router.
R2#demonstrate ip route ospf
O E2 sixteen.0.0.0/six [a hundred and ten/twenty] by way of 172.12.123.one, 00:00:05, Serial0
Permit’s return to R1 and take a look at its OSPF table.
R1#display ip route ospf
O 16.0.0.0/six can be a summary, 00:01:fifty one, Null0
Exactly where did the null0 interface https://www.totomvp.net/ originate from, and why can it be there? Packets despatched into the null interface are dropped, and in this case, that’s a superb matter.
After you configure summary routes in OSPF, a path to null0 will probably be mounted to the OSPF routing desk. This helps to forestall http://www.bbc.co.uk/search?q=토토사이트 routing loops. Any packets destined with the routes that have been summarized can have a longer match in the routing table, as revealed underneath…
C seventeen.0.0.0/eight is directly related, Loopback17
C sixteen.0.0.0/8 is right related, Loopback16
C 19.0.0.0/eight is specifically connected, Loopback19
C 18.0.0.0/eight is specifically related, Loopback18
O sixteen.0.0.0/6 is a summary, 00:01:fifty one, Null0
.. and packets that don't match among the summarized routes but do match the summary route might be dropped.
Blocking routing loops when performing route redistribution and summarization is vital. OSPF offers us a bit assist in that regard in this case, and as you analyze extra complex redistribution scenarios on the method to the CCNP and CCIE, you’ll realize that we’ll acquire all the help we could possibly get!