CCNP / BSCI Examination Tutorial: Route Summarization Plus the OSPF Null Interface
CCNP Examination 토토사이트 achievement, specifically within the BSCI Examination, requires you recognize the main points of route summarization. This ability not only requires that you've a comfort and ease amount with binary conversions, but You should understand how and in which to apply route summarization with Just about every personal protocol.
You also have to be aware of the “Negative effects” of route summarization. With OSPF, there will truly be an extra interface designed at The purpose of summarization, and this catches a lot of CCNP candidates without warning. Let’s Consider the null0 interface And the way it relates to OSPF summarization.
On R1, the next networks are redistributed into OSPF, and after that summarized.
interface Loopback16
ip handle 16.sixteen.16.sixteen 255.0.0.0
interface Loopback17
ip tackle seventeen.seventeen.seventeen.17 255.0.0.0
interface Loopback18
ip handle eighteen.eighteen.eighteen.eighteen 255.0.0.0
interface Loopback19
ip deal with 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 address seems on R2, a downstream router.
R2#display ip route ospf
O E2 16.0.0.0/six [one hundred ten/twenty] through 172.12.123.one, 00:00:05, Serial0
Allow’s return to R1 and take a look at its OSPF table.
R1#demonstrate ip route ospf
O 16.0.0.0/six is a summary, 00:01:fifty one, Null0
Exactly where did the null0 interface originate from, and why can it be there? Packets despatched on the null interface are dropped, and In such cases, that’s a good issue.
Once you configure summary routes in OSPF, a path to null0 might be mounted into your OSPF routing desk. This can help to prevent routing loops. Any packets destined with the routes that were summarized can have an extended match during the routing table, as shown under…
C seventeen.0.0.0/8 is directly linked, Loopback17
C 16.0.0.0/8 is specifically linked, Loopback16
C 19.0.0.0/8 is instantly linked, Loopback19
C 18.0.0.0/8 is directly related, Loopback18
O sixteen.0.0.0/six is usually a summary, 00:01:51, Null0
.. and packets that don't match among the summarized routes but do match the summary route might be dropped.
Avoiding routing loops when performing route redistribution and summarization is important. OSPF gives us somewhat help in that regard in this case, and as you review more advanced redistribution scenarios on the approach to the CCNP and CCIE, you’ll recognize that we’ll get all the help we could get!