CCNP / BSCI Examination Tutorial: Route Summarization Along with the OSPF Null Interface
CCNP exam achievements, specially on the BSCI Examination, calls for you fully grasp the small print of route summarization. This ability not just calls for you have a comfort amount with binary conversions, but You must know how and exactly where to use route summarization with Each and every person protocol.
You even have to understand the “Uncomfortable side effects” of route summarization. With OSPF, there will truly be an extra interface developed at the point of summarization, which catches many CCNP candidates abruptly. 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 you can summarized.
interface Loopback16
ip deal with 16.16.16.16 255.0.0.0
interface Loopback17
ip handle seventeen.seventeen.17.seventeen 255.0.0.0
interface Loopback18
ip handle eighteen.18.18.eighteen 255.0.0.0
interface Loopback19
ip address 19.19.19.19 255.0.0.0
R1(config)#router ospf 1
R1(config-router)#redistribute related subnets
R1(config-router)#summary-handle 16.0.0.0 252.0.0.0
The summary deal with seems on R2, a downstream router.
R2#present ip route ospf
O E2 16.0.0.0/6 [one hundred ten/twenty] by way of 172.twelve.123.1, 00:00:05, Serial0
Permit’s go back to R1 and look at its OSPF table.
R1#clearly show ip route ospf
O sixteen.0.0.0/six is usually a summary, 00:01:fifty one, Null0
In which did the null0 interface originate from, and why could it be there? Packets sent on the null interface are dropped, and In cases like this, that’s a fantastic matter.
Once you configure summary routes in OSPF, a route to null0 might be set up in the OSPF routing desk. This helps to avoid routing loops. Any packets destined for that routes that were summarized may have a longer match inside 토토사이트 the routing table, as demonstrated below…
C 17.0.0.0/eight is specifically linked, Loopback17
C sixteen.0.0.0/8 is directly connected, Loopback16
C 19.0.0.0/8 is specifically linked, Loopback19
C 18.0.0.0/eight is straight related, Loopback18
O sixteen.0.0.0/six is often a summary, 00:01:fifty one, Null0
.. and packets that do not match on the list of summarized routes but do match the summary route might be dropped.
Protecting against routing loops when performing route redistribution and summarization is vital. OSPF presents us a bit assist in that regard in this example, and when you examine much more complicated redistribution situations in your technique to the CCNP and CCIE, you’ll recognize that we’ll take all the assistance we will get!