CCNP / BSCI Examination Tutorial: Route Summarization Plus the OSPF Null 먹튀검증 Interface
CCNP Examination good results, especially around the BSCI Examination, requires you understand the details of route summarization. This ability not just demands that you've a comfort level with binary conversions, but It's important to know the way and the place to apply route summarization with Just about every specific protocol.
You also have to grasp the “Negative effects” of route summarization. With OSPF, there'll actually be an additional interface developed at The purpose of summarization, which catches a great deal of CCNP candidates without warning. Allow’s Look into the null0 interface And exactly how it relates to OSPF summarization.
On R1, the subsequent networks are redistributed into OSPF, and after that summarized.
interface Loopback16
ip address sixteen.sixteen.sixteen.sixteen 255.0.0.0
interface Loopback17
ip address 17.seventeen.17.seventeen 255.0.0.0
interface Loopback18
ip handle 18.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-tackle 16.0.0.0 252.0.0.0
The summary deal with appears on R2, a downstream router.
R2#clearly show ip route ospf
O E2 sixteen.0.0.0/6 [one hundred ten/twenty] through 172.twelve.123.one, 00:00:05, Serial0
Let’s return to R1 and evaluate its OSPF desk.
R1#present ip route ospf
O 16.0.0.0/6 is often a summary, 00:01:51, Null0
The place did the null0 interface come from, and why can it be there? Packets despatched into the null interface are dropped, and In cases like this, that’s a superb detail.
When you configure summary routes in OSPF, a route to null0 might be set up in to the OSPF routing desk. This can help to forestall routing loops. Any packets destined with the routes that have been summarized should have an extended match within the routing table, as revealed below…
C seventeen.0.0.0/8 is directly connected, Loopback17
C sixteen.0.0.0/8 is instantly linked, Loopback16
C 19.0.0.0/8 is right related, Loopback19
C 18.0.0.0/eight is right related, Loopback18
O 16.0.0.0/six can be a summary, 00:01:fifty one, Null0
.. and packets that do not match one of the summarized routes but do match the summary route will likely be dropped.
Blocking routing loops when carrying out route redistribution and summarization is vital. OSPF gives us just a little help in that regard in this situation, and as you analyze a lot more complicated redistribution eventualities on the strategy to the CCNP and CCIE, you’ll understand that we’ll consider all the help we can get!