CCNP / BSCI Test Tutorial: Route Summarization As well as OSPF Null Interface
CCNP exam accomplishment, specifically within the BSCI exam, needs you understand the main points of route summarization. This ability don't just needs 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 Just about every person protocol.
You also have to know the “Unwanted side effects” of route summarization. With OSPF, there'll truly be 먹튀검증 an additional interface made at The purpose of summarization, which catches a great deal of CCNP candidates without warning. Let’s Have a look at the null0 interface And exactly how it relates to OSPF summarization.
On R1, the following networks are redistributed into OSPF, after which summarized.
interface Loopback16
ip tackle sixteen.16.sixteen.16 255.0.0.0
interface Loopback17
ip tackle seventeen.seventeen.seventeen.seventeen 255.0.0.0
interface Loopback18
ip deal with 18.eighteen.eighteen.eighteen 255.0.0.0
interface Loopback19
ip address 19.19.19.19 255.0.0.0
R1(config)#router ospf one
R1(config-router)#redistribute linked subnets
R1(config-router)#summary-address 16.0.0.0 252.0.0.0
The summary tackle seems on R2, a downstream router.
R2#demonstrate ip route ospf
O E2 sixteen.0.0.0/six [110/twenty] via 172.12.123.one, 00:00:05, Serial0
Enable’s go back to R1 and look at its OSPF table.
R1#display ip route ospf
O 16.0.0.0/6 can be a summary, 00:01:fifty one, Null0
The place 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 a great detail.
If you configure summary routes in OSPF, a path to null0 are going to be mounted in to the OSPF routing table. This can help to circumvent routing loops. Any packets destined for that routes which have been summarized could have a longer match in the routing desk, as demonstrated below…
C 17.0.0.0/eight is immediately connected, Loopback17
C sixteen.0.0.0/eight is right linked, Loopback16
C 19.0.0.0/8 is specifically linked, Loopback19
C eighteen.0.0.0/8 is immediately linked, Loopback18
O 16.0.0.0/6 is really a summary, 00:01:51, Null0
.. and packets that do not match one of several summarized routes but do match the summary route will be dropped.
Avoiding routing loops when accomplishing route redistribution and summarization is important. OSPF provides us just a little assist in that regard in this example, and while you review additional advanced redistribution scenarios with your way to the CCNP and CCIE, you’ll know that we’ll consider all the help we will get!