CCNP / BSCI Examination Tutorial: Route Summarization As well as OSPF Null Interface
CCNP Examination good results, significantly over the BSCI exam, needs you recognize the small print of route summarization. This talent not only demands you have a comfort and ease level with 먹튀검증 binary conversions, but you have to know how and in which to apply route summarization with Every single unique protocol.
You even have to know the “Unwanted effects” of route summarization. With OSPF, there will actually be an additional interface established at the point of summarization, and this catches lots of CCNP candidates by surprise. Permit’s Check out the null0 interface and how it pertains to OSPF summarization.
On R1, the following networks are redistributed into OSPF, after which you can summarized.
interface Loopback16
ip deal with 16.16.16.sixteen 255.0.0.0
interface Loopback17
ip address 17.seventeen.seventeen.17 255.0.0.0
interface Loopback18
ip deal with eighteen.eighteen.eighteen.eighteen 255.0.0.0
interface Loopback19
ip handle 19.19.19.19 255.0.0.0
R1(config)#router ospf one
R1(config-router)#redistribute connected subnets
R1(config-router)#summary-deal with sixteen.0.0.0 252.0.0.0
The summary deal with seems on R2, a downstream router.
R2#demonstrate ip route ospf
O E2 16.0.0.0/6 [110/twenty] by using 172.twelve.123.one, 00:00:05, Serial0
Permit’s return to R1 and evaluate its OSPF table.
R1#show ip route ospf
O sixteen.0.0.0/6 is actually a summary, 00:01:51, Null0
Where by did the null0 interface come from, and why could it be there? Packets sent towards the null interface are dropped, and In cases like this, that’s a fantastic point.
If you configure summary routes in OSPF, a route to null0 might be put in into your OSPF routing table. This assists to avoid routing loops. Any packets destined to the routes which were summarized will have a longer match inside the routing desk, as proven beneath…
C 17.0.0.0/eight is specifically linked, Loopback17
C sixteen.0.0.0/eight is specifically related, Loopback16
C 19.0.0.0/8 is instantly linked, Loopback19
C eighteen.0.0.0/eight is specifically connected, Loopback18
O sixteen.0.0.0/six is often a summary, 00:01:fifty one, Null0
.. and packets that don't match among the list of summarized routes but do match the summary route are going to be dropped.
Protecting against routing loops when carrying out route redistribution and summarization is significant. OSPF offers us somewhat help in that regard in this situation, and while you analyze much more elaborate redistribution scenarios on the strategy to the CCNP and CCIE, you’ll recognize that we’ll take all the assistance we can get!