CCNP / BSCI Examination Tutorial: Route Summarization And also the OSPF Null Interface
CCNP exam achievements, significantly within the BSCI Examination, needs you realize the details of route summarization. This talent not simply demands you have a comfort degree with binary conversions, but It's important to know the way and wherever to apply route summarization with Every single unique protocol.
You even have to grasp the “side effects” of route summarization. With OSPF, there'll really be an additional interface developed at The purpose of summarization, which catches a lot of CCNP candidates unexpectedly. Permit’s Look into the null0 interface And the way it pertains to OSPF summarization.
On R1, the next networks are redistributed into OSPF, then summarized.
interface Loopback16
ip tackle 16.16.sixteen.16 255.0.0.0
interface Loopback17
ip tackle 17.17.seventeen.seventeen 255.0.0.0
interface Loopback18
ip address 18.eighteen.eighteen.eighteen 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 linked subnets
R1(config-router)#summary-deal with sixteen.0.0.0 252.0.0.0
The summary deal with appears on R2, a downstream router.
R2#show ip route ospf
O E2 sixteen.0.0.0/six [110/twenty] by way of 172.twelve.123.1, 00:00:05, Serial0
Enable’s return to R1 and take a look at its OSPF table.
R1#display ip route ospf
O 16.0.0.0/6 is a summary, 00:01:51, Null0
In which did the null0 interface come from, and why is it there? Packets despatched into the null interface are dropped, and In this instance, that’s an excellent thing.
Once you configure summary routes in OSPF, a path to null0 will probably be installed in the OSPF routing table. This will help to stop routing loops. Any packets destined for your routes that were summarized may have a longer match in the routing desk, as demonstrated down below…
C 17.0.0.0/eight is immediately connected, Loopback17
C 16.0.0.0/8 is immediately connected, Loopback16
C 19.0.0.0/8 is immediately connected, Loopback19
C eighteen.0.0.0/8 is right connected, Loopback18
O sixteen.0.0.0/6 is really a summary, 00:01:51, Null0
.. and packets that don't match one of many summarized routes but do match the summary route are going to be dropped.
Preventing routing loops when executing route redistribution and summarization is important. 토토 OSPF presents us a little bit help in that regard in this example, and when you research a lot more complicated redistribution situations on your solution to the CCNP and CCIE, you’ll know that we’ll get all the assistance we will get!