CCNP / BSCI Examination Tutorial: Route Summarization As well as OSPF Null Interface
CCNP Examination success, specially around the BSCI exam, needs you have an understanding of the details of route summarization. This ability not just necessitates that you've got a ease and comfort degree with binary conversions, but You should know how and where to use route summarization with Each individual individual protocol.
You even have to learn the “Unwanted effects” of route summarization. With OSPF, there will actually be an additional interface developed at the point of summarization, and this catches lots 토토 of CCNP candidates unexpectedly. Permit’s Examine the null0 interface And just how it relates to OSPF summarization.
On R1, the following networks are redistributed into OSPF, then summarized.
interface Loopback16
ip tackle sixteen.16.16.sixteen 255.0.0.0
interface Loopback17
ip tackle 17.17.17.17 255.0.0.0
interface Loopback18
ip deal with eighteen.18.18.18 255.0.0.0
interface Loopback19
ip handle 19.19.19.19 255.0.0.0
R1(config)#router ospf one
R1(config-router)#redistribute related subnets
R1(config-router)#summary-address 16.0.0.0 252.0.0.0
The summary tackle appears on R2, a downstream router.
R2#display ip route ospf
O E2 16.0.0.0/six [a hundred and ten/20] by using 172.12.123.1, 00:00:05, Serial0
Permit’s go back to R1 and check out its OSPF desk.
R1#present ip route ospf
O sixteen.0.0.0/six is often a summary, 00:01:fifty one, Null0
Where by did the null0 interface come from, and why can it be there? Packets despatched to your null interface are dropped, and in this case, that’s a great factor.
After you configure summary routes in OSPF, a route to null0 is going to be installed in the OSPF routing desk. This can help to circumvent routing loops. Any packets destined to the routes which were summarized may have a longer match within the routing table, as demonstrated down below…
C 17.0.0.0/eight is instantly connected, Loopback17
C 16.0.0.0/eight is straight linked, Loopback16
C 19.0.0.0/eight is instantly connected, Loopback19
C 18.0.0.0/eight is straight linked, Loopback18
O sixteen.0.0.0/6 can be a summary, 00:01:51, Null0
.. and packets that do not match among the list of summarized routes but do match the summary route are going to be dropped.
Blocking routing loops when executing route redistribution and summarization is significant. OSPF presents us a little http://edition.cnn.com/search/?text=토토사이트 bit help in that regard in this situation, and as you review a lot more sophisticated redistribution scenarios with your way to the CCNP and CCIE, you’ll realize that we’ll consider all the assistance we will get!