CCNP / BSCI Exam Tutorial: Route Summarization And also the OSPF Null Interface
CCNP Examination success, especially about the BSCI Examination, requires you understand the small print of route summarization. This ability not simply needs you have a comfort and ease degree with binary conversions, but You must know the way and where by to use route summarization with Every specific protocol.
You also have to know the “Negative effects” of route summarization. With OSPF, there'll essentially be an additional interface developed at the point of summarization, which catches loads of CCNP candidates without warning. Allow’s Consider the null0 interface And just how it pertains to OSPF summarization.
On R1, the following networks are redistributed into OSPF, then summarized.
interface Loopback16
ip deal with 16.16.sixteen.sixteen 255.0.0.0
interface Loopback17
ip address seventeen.seventeen.seventeen.17 255.0.0.0
interface Loopback18
ip deal with 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 related subnets
R1(config-router)#summary-deal with sixteen.0.0.0 252.0.0.0
The summary tackle seems on R2, a downstream router.
R2#demonstrate ip route ospf
O E2 sixteen.0.0.0/six [one hundred ten/twenty] by using 172.twelve.123.one, 00:00:05, Serial0
Let’s return to R1 and examine its OSPF table.
R1#demonstrate ip route ospf
O sixteen.0.0.0/six is often a summary, http://query.nytimes.com/search/sitesearch/?action=click&contentCollection®ion=TopBar&WT.nav=searchWidget&module=SearchSubmit&pgtype=Homepage#/토토사이트 00:01:51, Null0
Where by did the null0 interface originate from, and why can it be there? Packets despatched for the null interface are dropped, and in this case, that’s a very good factor.
If you configure summary routes in OSPF, a route to null0 are going to be set up in the OSPF routing table. This assists to prevent routing loops. Any packets destined to the routes which have been summarized will likely have a longer match inside the routing desk, as demonstrated down below…
C 17.0.0.0/8 is specifically related, Loopback17
C sixteen.0.0.0/eight is specifically linked, Loopback16
C 19.0.0.0/eight is immediately linked, Loopback19
C 18.0.0.0/eight is directly connected, Loopback18
O 16.0.0.0/six is really a summary, 00:01:51, Null0
.. and packets that don't match one of the summarized routes but do match the summary route will likely be dropped.
Stopping routing loops when executing route redistribution and summarization is vital. OSPF presents us a little bit assist in that regard in this situation, and while you study much more complex redistribution scenarios on your own way to the CCNP and CCIE, you’ll understand that we’ll take all 토토 the help we could possibly get!