CCNP / BSCI Test Tutorial: Route Summarization As well as OSPF Null Interface
CCNP exam success, significantly about the BSCI exam, demands you fully grasp the small print of route summarization. This talent not just involves you have a convenience amount with binary conversions, but You need to understand how and where by to apply route summarization with Each individual particular person protocol.
You even have to find out the “Unwanted side effects” of route summarization. With OSPF, there will basically be an additional interface designed at the point of summarization, which catches loads of CCNP candidates by surprise. Allow’s Have a look at the null0 interface and how it pertains to OSPF summarization.
On R1, the subsequent networks are redistributed into OSPF, then summarized.
interface Loopback16
ip deal with 16.16.sixteen.sixteen 255.0.0.0
interface Loopback17
ip deal with seventeen.17.seventeen.17 255.0.0.0
interface Loopback18
ip deal with 18.eighteen.18.18 255.0.0.0
interface Loopback19
ip handle 19.19.19.19 255.0.0.0
R1(config)#router ospf 1
R1(config-router)#redistribute 토토사이트 linked subnets
R1(config-router)#summary-tackle sixteen.0.0.0 252.0.0.0
The summary deal with seems on R2, a downstream router.
R2#display ip route ospf
O E2 16.0.0.0/six [a hundred and ten/twenty] by way of 172.12.123.1, 00:00:05, Serial0
Allow’s go back to R1 and have a look at its OSPF desk.
R1#exhibit ip route ospf
O sixteen.0.0.0/six is usually a summary, 00:01:fifty one, Null0
Where did the null0 interface come from, and why could it be there? Packets sent to your null interface are dropped, and In this instance, that’s a fantastic detail.
Once you configure summary routes in OSPF, a route to null0 will likely be set up into your OSPF routing table. This allows to prevent routing loops. Any packets destined to the routes that have been summarized will likely have a longer match from the routing table, as demonstrated underneath…
C 17.0.0.0/eight is straight related, Loopback17
C sixteen.0.0.0/eight is straight connected, Loopback16
C 19.0.0.0/8 is immediately linked, Loopback19
C 18.0.0.0/8 is immediately linked, Loopback18
O 16.0.0.0/six is usually a summary, 00:01:fifty one, Null0
.. and packets that do not match one of the summarized routes but do match the summary route are going to be dropped.
Avoiding routing loops when accomplishing route redistribution and http://www.thefreedictionary.com/토토사이트 summarization is important. OSPF presents us a little assist in that regard in this situation, and when you study far more advanced redistribution situations on your solution to the CCNP and CCIE, you’ll realize that we’ll choose all the help we might get!