CCNP / BSCI Examination Tutorial: Route Summarization Along with the OSPF Null Interface
CCNP Examination achievements, particularly to the BSCI Test, calls for you fully grasp the main points of route summarization. This ability not just requires that you've a convenience amount with binary conversions, but you have to know the way and in which to apply route summarization with Just about every individual protocol.
You even have to understand the “Uncomfortable side effects” of route summarization. With OSPF, there'll truly be an additional interface produced at The purpose of summarization, which catches a great deal of CCNP candidates unexpectedly. Let’s Look into the null0 interface And the way it pertains to OSPF summarization.
On R1, the subsequent networks are redistributed into OSPF, then summarized.
interface Loopback16
ip tackle 16.sixteen.sixteen.16 255.0.0.0
interface Loopback17
ip handle 17.17.17.seventeen 255.0.0.0
interface Loopback18
ip handle eighteen.18.18.eighteen 255.0.0.0
interface Loopback19
ip tackle 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 address appears on R2, a downstream router.
R2#show ip route ospf
O E2 16.0.0.0/6 [110/twenty] by using 172.12.123.one, 00:00:05, Serial0
Let’s go back to R1 and examine its OSPF table.
R1#demonstrate ip route ospf
O sixteen.0.0.0/six can be a summary, 00:01:fifty one, Null0
Exactly where did the null0 interface come from, and why can it be there? Packets despatched into the null interface are dropped, and In cases like this, that’s a good point.
Whenever you configure summary routes in OSPF, a route to null0 will likely be installed in the OSPF routing desk. This will help to avoid routing loops. Any packets destined to the routes which have been summarized could have a longer match in the routing table, as demonstrated below…
C 먹튀검증 seventeen.0.0.0/eight is specifically linked, Loopback17
C 16.0.0.0/eight is directly linked, Loopback16
C 19.0.0.0/8 is instantly related, Loopback19
C eighteen.0.0.0/8 is immediately connected, Loopback18
O sixteen.0.0.0/6 is often a summary, 00:01:fifty one, Null0
.. and packets that do not match one of several summarized routes but do match the summary route might be dropped.
Stopping routing loops when doing route redistribution and summarization is significant. OSPF offers us a bit assist in that regard in this case, and as you review much more advanced redistribution eventualities in your way to the CCNP and CCIE, you’ll know that we’ll just take all the help we may get!