CCNP / BSCI Exam Tutorial: Route Summarization As well as the OSPF Null Interface
CCNP exam achievement, notably within the BSCI exam, needs you have an understanding of the details of route summarization. This ability not only needs that you've got a convenience degree with binary conversions, but It's important to know the way and the place to apply route summarization with Each individual specific protocol.
You even have to learn the “Unintended effects” of route summarization. With OSPF, there will actually be an extra interface produced at The purpose of summarization, and this catches plenty of CCNP candidates unexpectedly. Allow’s Look into the null0 interface And the way it pertains to OSPF summarization.
On R1, the following networks are redistributed into OSPF, and afterwards summarized.
interface Loopback16
ip deal with 16.16.sixteen.sixteen 255.0.0.0
interface Loopback17
ip deal with seventeen.seventeen.17.seventeen 255.0.0.0
interface Loopback18
ip handle eighteen.18.eighteen.18 255.0.0.0
interface Loopback19
ip address 19.19.19.19 255.0.0.0
R1(config)#router ospf one
R1(config-router)#redistribute related subnets
R1(config-router)#summary-handle 16.0.0.0 252.0.0.0
The summary address appears on R2, a downstream router.
R2#exhibit ip route ospf
O E2 16.0.0.0/6 [110/twenty] by means of 172.12.123.one, 00:00:05, Serial0
Let’s return to R1 and have a look at its OSPF desk.
R1#display ip route ospf
O sixteen.0.0.0/six can be a summary, 00:01:fifty one, Null0
Where by did the null0 interface come from, and why can it be there? Packets despatched to your null interface are dropped, and In this instance, that’s a fantastic detail.
Any time you configure summary routes in OSPF, a route to null0 will probably be mounted in the OSPF routing desk. This can help to forestall routing loops. Any packets destined for the 먹튀검증 routes which were summarized should have an extended match during the routing table, as revealed underneath…
C 17.0.0.0/eight is instantly linked, Loopback17
C 16.0.0.0/8 is immediately linked, Loopback16
C 19.0.0.0/8 is instantly connected, Loopback19
C 18.0.0.0/8 is right connected, Loopback18
O sixteen.0.0.0/six is a summary, 00:01:51, Null0
.. and packets that don't match on the list of summarized routes but do match the summary route are going to be dropped.
Avoiding routing loops when carrying out route redistribution and summarization is significant. OSPF gives us a bit assist in that regard in this example, and when you analyze a lot more sophisticated redistribution eventualities in your method to the CCNP and CCIE, you’ll understand that we’ll consider all the assistance we could get!