CCNP / BSCI Exam Tutorial: Route Summarization And also the OSPF Null Interface
CCNP exam results, specifically over the BSCI Examination, calls for you fully grasp the main points of route summarization. This ability don't just needs that you've a ease and comfort amount with binary conversions, but you have to understand how and where to apply route summarization with Every single unique protocol.
You also have to be aware of the “side effects” of route summarization. With OSPF, there will essentially be an additional interface created at The purpose of summarization, which catches lots of CCNP candidates without warning. Permit’s Look into the null0 interface And exactly how it relates to 토토사이트 OSPF summarization.
On R1, the following networks are redistributed into OSPF, after which summarized.
interface Loopback16
ip tackle 16.16.sixteen.16 255.0.0.0
interface Loopback17
ip address 17.17.seventeen.17 255.0.0.0
interface Loopback18
ip tackle eighteen.18.eighteen.18 255.0.0.0
interface Loopback19
ip deal with 19.19.19.19 255.0.0.0
R1(config)#router ospf 1
R1(config-router)#redistribute related subnets
R1(config-router)#summary-deal with sixteen.0.0.0 252.0.0.0
The summary address appears on R2, a downstream router.
R2#exhibit ip route ospf
O E2 sixteen.0.0.0/6 [110/20] by way of 172.twelve.123.one, 00:00:05, Serial0
Allow’s return to R1 and evaluate its OSPF table.
R1#display ip route ospf
O 16.0.0.0/6 is actually a summary, 00:01:51, Null0
The place did the null0 interface originate from, and why can it be there? Packets sent to your null interface are dropped, and In cases like this, that’s a fantastic issue.
Once you configure summary routes in OSPF, a route to null0 will probably be put in into the OSPF routing desk. This will help to stop routing loops. Any packets destined for that routes which have been summarized can have an extended match during the routing desk, as shown under…
C seventeen.0.0.0/eight is specifically connected, Loopback17
C sixteen.0.0.0/eight is specifically related, Loopback16
C 19.0.0.0/eight is right related, Loopback19
C eighteen.0.0.0/8 is instantly related, Loopback18
O 16.0.0.0/6 is often 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 probably be dropped.
Avoiding routing loops when performing route redistribution and summarization is important. OSPF presents us somewhat help in that regard in this example, and when you research extra sophisticated redistribution situations in your method to the CCNP and CCIE, you’ll know that we’ll acquire all the assistance we will get!