CCNP / BSCI Examination Tutorial: Route Summarization As well as OSPF Null Interface
CCNP Test accomplishment, significantly about the BSCI Examination, needs you realize the small print of route summarization. This 먹튀검증 talent not only necessitates that you've a comfort and ease stage with binary conversions, but It's important to know the way and in which to apply route summarization with Every single unique protocol.
You also have to understand the “Uncomfortable side effects” of route summarization. With OSPF, there'll actually be an additional interface established at the point of summarization, which catches a lot of CCNP candidates without warning. Let’s Consider the null0 interface And exactly how it pertains to OSPF summarization.
On R1, the following networks are redistributed into OSPF, then summarized.
interface Loopback16
ip handle 16.16.16.16 255.0.0.0
interface Loopback17
ip address 17.17.seventeen.seventeen 255.0.0.0
interface Loopback18
ip address eighteen.18.eighteen.18 255.0.0.0
interface Loopback19
ip handle 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 handle seems on R2, a downstream router.
R2#exhibit ip route ospf
O E2 16.0.0.0/6 [a hundred and ten/twenty] through 172.twelve.123.1, 00:00:05, Serial0
Enable’s return to R1 and examine its OSPF table.
R1#present ip route ospf
O 16.0.0.0/6 is often a summary, 00:01:51, Null0
Where did the null0 interface originate from, and why can it be there? Packets sent into the null interface are dropped, and In such a case, that’s an excellent issue.
If you configure summary routes in OSPF, a route to null0 will probably be put in in to the OSPF routing table. This will help to forestall routing loops. Any packets destined to the routes which have been summarized should have an extended match within the routing table, as proven beneath…
C seventeen.0.0.0/eight is directly connected, Loopback17
C 16.0.0.0/8 is specifically related, Loopback16
C 19.0.0.0/eight is directly linked, Loopback19
C 18.0.0.0/8 is right related, Loopback18
O sixteen.0.0.0/6 is really a summary, 00:01:51, Null0
.. and packets that do not match one of many summarized routes but do match the summary route are going to be dropped.
Avoiding routing loops when accomplishing route redistribution and summarization is significant. OSPF provides us a little assist in that regard in this situation, and when you analyze far more complicated redistribution situations with your way to the CCNP and CCIE, you’ll know that we’ll take all the assistance we might get!