CCNP / BSCI Examination Tutorial: Route Summarization As well as the OSPF Null Interface
CCNP Examination achievements, specifically to the BSCI exam, needs you realize the main points of route summarization. This skill not only demands you have a comfort degree with binary conversions, but you have to know the way and the place to use route summarization with Every personal protocol.
You also have to grasp the “side effects” of route summarization. With OSPF, there'll actually be an extra interface established at the point of summarization, which catches many CCNP candidates unexpectedly. Let’s Have a look at the null0 interface And exactly how it pertains to OSPF summarization.
On R1, the subsequent networks are redistributed into OSPF, and afterwards summarized.
interface Loopback16
ip address 16.16.sixteen.sixteen 255.0.0.0
interface Loopback17
ip deal with 17.seventeen.seventeen.17 255.0.0.0
interface Loopback18
ip tackle 18.eighteen.eighteen.18 255.0.0.0
interface Loopback19
ip address 19.19.19.19 255.0.0.0
R1(config)#router ospf 1
R1(config-router)#redistribute linked subnets
R1(config-router)#summary-tackle sixteen.0.0.0 252.0.0.0
The summary tackle seems on R2, a downstream router.
R2#display ip route ospf
O E2 sixteen.0.0.0/six [110/20] by using 172.12.123.1, 00:00:05, Serial0
Allow’s return to R1 and take a look at its OSPF table.
R1#present ip route ospf
O 16.0.0.0/six is often a summary, 00:01:51, Null0
In which did the null0 interface originate from, and why is it there? Packets sent to your null interface are dropped, and In cases like this, that’s a good factor.
When you configure summary routes in OSPF, a path to null0 will be set up in to the OSPF routing table. This helps to prevent routing loops. Any packets destined to the routes that were summarized will likely have an extended match from the routing desk, as demonstrated under…
C seventeen.0.0.0/eight is instantly connected, Loopback17
C sixteen.0.0.0/8 is instantly connected, Loopback16
C 19.0.0.0/8 is straight connected, Loopback19
C eighteen.0.0.0/8 is right linked, Loopback18
O 16.0.0.0/six is usually a summary, 00:01:51, Null0
.. and packets that don't match one of the summarized 토토 routes but do match the summary route will be dropped.
Preventing routing loops when doing route redistribution and summarization is vital. OSPF gives us a little bit assist in that regard in this situation, and as you examine a lot more complicated redistribution eventualities with your technique to the CCNP and CCIE, you’ll recognize that we’ll choose all the assistance we will get!