CCNP / BSCI Test Tutorial: Route Summarization And The OSPF Null Interface
CCNP Examination accomplishment, significantly to the BSCI Test, calls for you understand the details of route summarization. This ability not simply calls for that you have a comfort degree with binary conversions, but You will need to know the way and exactly where to apply route summarization with Each individual specific protocol.
You also have to be aware of the “Negative effects” of route summarization. With OSPF, there will truly be an additional interface developed at the point of summarization, which catches a lot of CCNP candidates by surprise. Enable’s Look into the null0 interface And the way it pertains to OSPF summarization.
On R1, the following networks are redistributed into OSPF, after which summarized.
interface Loopback16
ip tackle 16.sixteen.sixteen.sixteen 255.0.0.0
interface Loopback17
ip deal with seventeen.seventeen.17.seventeen 255.0.0.0
interface Loopback18
ip handle 18.eighteen.18.eighteen 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#show ip route ospf
O E2 16.0.0.0/6 [one hundred ten/20] by means of 172.twelve.123.one, 00:00:05, Serial0
Permit’s return to R1 and have a look at its OSPF desk.
R1#demonstrate ip route ospf
O 16.0.0.0/six is often a summary, 00:01:51, Null0
Exactly where did the null0 interface originate from, and why can it be there? Packets sent to the null interface are dropped, and In such cases, that’s a good factor.
After you configure summary routes in OSPF, a route to null0 will probably be set up to the OSPF routing table. This allows to circumvent routing loops. Any packets destined for your routes that have been summarized could have an extended match inside the routing table, as proven underneath…
C 17.0.0.0/eight is directly linked, Loopback17
C sixteen.0.0.0/eight is instantly linked, Loopback16
C 19.0.0.0/8 is immediately linked, Loopback19
C eighteen.0.0.0/eight is directly related, Loopback18
O sixteen.0.0.0/six is a summary, 00:01:51, Null0
.. and packets that do not match one of several summarized routes but do match 토토사이트 the summary route will be dropped.
Preventing routing loops when undertaking route redistribution and summarization is important. OSPF offers us a bit assist in that regard in this case, and when you analyze much more complex redistribution scenarios on the way to the CCNP and CCIE, you’ll http://www.bbc.co.uk/search?q=토토사이트 recognize that we’ll just take all the help we could get!