CCNP / BSCI Exam Tutorial: Route Summarization As well as the OSPF Null Interface
CCNP exam achievement, specifically over the BSCI Examination, calls for you recognize the main points of route summarization. This ability not just involves that you have a comfort and ease stage with binary conversions, but You will need to know how and wherever to use route summarization with Each and every individual protocol.
You also have to find out the “side effects” of route summarization. With OSPF, there'll really be 토토 an additional interface made at The purpose of summarization, and this catches lots of CCNP candidates without warning. Let’s Consider the null0 interface And just how it relates to OSPF summarization.
On R1, the following networks are redistributed into OSPF, and afterwards summarized.
interface Loopback16
ip handle 16.sixteen.16.16 255.0.0.0
interface Loopback17
ip tackle seventeen.seventeen.17.seventeen 255.0.0.0
interface Loopback18
ip deal with 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 connected subnets
R1(config-router)#summary-handle 16.0.0.0 252.0.0.0
The summary handle seems on R2, a downstream router.
R2#demonstrate ip route ospf
O E2 sixteen.0.0.0/six [one hundred ten/20] by means of 172.twelve.123.1, 00:00:05, Serial0
Let’s go back to R1 and have a look at its OSPF table.
R1#show ip route ospf
O 16.0.0.0/six is often a summary, 00:01:51, Null0
Where by did the null0 interface come from, and why can it be there? Packets sent to the null interface are dropped, and In this instance, that’s an excellent issue.
Whenever you configure summary routes in OSPF, a route to null0 are going to be put in to the OSPF routing desk. This allows to circumvent routing loops. Any packets destined for the routes which have been summarized may have a longer match while in the routing table, as shown below…
C seventeen.0.0.0/eight is straight related, Loopback17
C 16.0.0.0/eight is instantly linked, Loopback16
C 19.0.0.0/8 is directly https://www.washingtonpost.com/newssearch/?query=토토사이트 related, Loopback19
C eighteen.0.0.0/8 is right linked, Loopback18
O 16.0.0.0/6 is usually a summary, 00:01:fifty one, Null0
.. and packets that don't match one of several summarized routes but do match the summary route will likely be dropped.
Protecting against routing loops when doing route redistribution and summarization is important. OSPF offers us a little bit help in that regard in this case, and while you review far more complex redistribution situations in your approach to the CCNP and CCIE, you’ll realize that we’ll acquire all the help we may get!