CCNP / BSCI Exam Tutorial: Route Summarization Plus the OSPF Null Interface
CCNP exam achievement, significantly around the BSCI exam, requires you have an understanding of the small print of route summarization. This ability not only necessitates that you've got a ease and comfort amount with binary conversions, but You must understand how and exactly where to apply route summarization with Every specific protocol.
You even have to understand the “Negative effects” of route summarization. With OSPF, there'll truly be an additional interface established at The purpose of summarization, which catches a great deal of CCNP candidates abruptly. Enable’s Look into the null0 interface And the way it relates to OSPF summarization.
On R1, the subsequent networks are redistributed into OSPF, and afterwards summarized.
interface Loopback16
ip tackle sixteen.sixteen.16.sixteen 255.0.0.0
interface Loopback17
ip tackle 17.17.seventeen.17 255.0.0.0
interface Loopback18
ip handle eighteen.18.18.18 255.0.0.0
interface Loopback19
ip handle 19.19.19.19 255.0.0.0
R1(config)#router ospf one
R1(config-router)#redistribute related subnets
R1(config-router)#summary-handle sixteen.0.0.0 252.0.0.0
The summary address seems on R2, a downstream router.
R2#demonstrate ip route ospf
O E2 sixteen.0.0.0/six [one hundred ten/twenty] by way of 172.12.123.1, 00:00:05, Serial0
Enable’s return to R1 and check out its 토토사이트 OSPF desk.
R1#exhibit ip route ospf
O sixteen.0.0.0/six is actually a summary, 00:01:51, Null0
The place did the null0 interface come from, and why could it be there? Packets despatched for the null interface are dropped, and In such a case, that’s a good detail.
Whenever you configure summary routes in OSPF, a path to null0 are going to be mounted to the OSPF http://www.thefreedictionary.com/토토사이트 routing desk. This can help to forestall routing loops. Any packets destined for that routes that have been summarized will likely have a longer match within the routing desk, as shown beneath…
C 17.0.0.0/8 is immediately connected, Loopback17
C 16.0.0.0/eight is immediately connected, Loopback16
C 19.0.0.0/8 is right connected, Loopback19
C eighteen.0.0.0/eight is directly connected, Loopback18
O sixteen.0.0.0/six can be a summary, 00:01:fifty one, Null0
.. and packets that don't match among the summarized routes but do match the summary route will probably be dropped.
Stopping routing loops when accomplishing route redistribution and summarization is significant. OSPF gives us a little assist in that regard in this example, and as you analyze additional complex redistribution scenarios with your method to the CCNP and CCIE, you’ll understand that we’ll choose all the help we might get!