CCNP / BSCI Exam Tutorial: Route Summarization As well as the OSPF Null Interface
CCNP exam achievements, specially on the BSCI Test, needs you understand the main points of route summarization. This talent not just requires that you've a comfort and ease level with binary conversions, but You need to know the way and where by to apply route summarization with each particular person protocol.
You even have to find out the “side effects” of route summarization. With OSPF, there'll really be an extra interface developed at The purpose of summarization, and this catches a great deal of CCNP candidates by surprise. Allow’s Check out the null0 interface and how it relates to OSPF summarization.
On R1, the next networks are redistributed into OSPF, and afterwards summarized.
interface Loopback16
ip tackle 16.16.16.sixteen 255.0.0.0
interface Loopback17
ip tackle 17.17.seventeen.seventeen 255.0.0.0
interface Loopback18
ip deal with eighteen.18.18.18 255.0.0.0
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 address seems on R2, a downstream router.
R2#demonstrate ip route ospf
O E2 16.0.0.0/6 [a hundred and ten/20] by way of 172.twelve.123.1, 00:00:05, Serial0
Allow’s go back to R1 and evaluate its OSPF table.
R1#present ip route ospf
O 16.0.0.0/six is actually a summary, 00:01:fifty one, Null0
Where did the null0 interface originate from, and http://query.nytimes.com/search/sitesearch/?action=click&contentCollection®ion=TopBar&WT.nav=searchWidget&module=SearchSubmit&pgtype=Homepage#/토토사이트 why could it be there? Packets despatched on the null interface are dropped, and In such a case, that’s a very good thing.
Once you configure summary routes in OSPF, a route to null0 is going to be put in in to the OSPF routing desk. This can help to forestall routing loops. Any 먹튀 packets destined for that routes which have been summarized may have a longer match during the routing table, as shown beneath…
C 17.0.0.0/8 is immediately connected, Loopback17
C sixteen.0.0.0/eight is right related, Loopback16
C 19.0.0.0/8 is specifically linked, Loopback19
C eighteen.0.0.0/8 is straight connected, Loopback18
O 16.0.0.0/six can be a summary, 00:01:fifty one, Null0
.. and packets that do not match one of the summarized routes but do match the summary route is going to be dropped.
Preventing routing loops when executing route redistribution and summarization is vital. OSPF provides us slightly help in that regard in this case, and while you study additional intricate redistribution situations in your approach to the CCNP and CCIE, you’ll understand that we’ll acquire all the help we might get!