CCNP / BSCI Examination Tutorial: Route Summarization Along with the OSPF Null Interface
CCNP Examination achievements, notably to the BSCI Examination, needs you recognize the details of route summarization. This ability not merely requires you have a comfort amount with binary conversions, but You will need to understand how and where to use route summarization with Just about every specific protocol.
You even have to know the “Unintended effects” of route summarization. With OSPF, there'll truly be an additional interface made at the point of summarization, which catches loads of CCNP candidates abruptly. Enable’s Have a look at the null0 interface and how it pertains to OSPF summarization.
On R1, the next networks are redistributed into OSPF, after which you can summarized.
interface Loopback16
ip tackle 16.16.16.16 255.0.0.0
interface Loopback17
ip address seventeen.17.seventeen.seventeen 255.0.0.0
interface Loopback18
ip deal with eighteen.eighteen.18.18 255.0.0.0
interface Loopback19
ip tackle 19.19.19.19 255.0.0.0
R1(config)#router ospf 1
R1(config-router)#redistribute related subnets
R1(config-router)#summary-deal with 16.0.0.0 252.0.0.0
The summary address appears on R2, a downstream router.
R2#demonstrate ip route ospf
O E2 16.0.0.0/6 [one hundred ten/20] through 172.12.123.1, 00:00:05, Serial0
Enable’s go back to R1 and take a look at its OSPF table.
R1#present ip route ospf
O sixteen.0.0.0/six is a summary, 00:01:fifty one, Null0
Where did the null0 interface come from, and why is it there? Packets despatched towards the null interface are dropped, and In cases like this, that’s an excellent thing.
Once you 토토사이트 configure summary routes in OSPF, a route to null0 will be set up in to the OSPF routing table. This assists to circumvent routing loops. Any packets destined for your routes which were summarized could have a longer match inside the routing desk, as proven down below…
C seventeen.0.0.0/eight is straight linked, Loopback17
C 16.0.0.0/8 is specifically related, Loopback16
C 19.0.0.0/8 is straight linked, Loopback19
C eighteen.0.0.0/eight is specifically connected, Loopback18
O 16.0.0.0/six is actually a summary, 00:01:fifty one, Null0
.. and packets that do not match among the summarized routes but do match the summary route will be dropped.
Protecting against routing loops when undertaking route redistribution and summarization is significant. OSPF offers us a little assist in that regard in this situation, and when you study a lot more intricate redistribution situations on the technique to the CCNP and CCIE, you’ll realize that we’ll choose all the assistance we may get!