CCNP / BSCI Test Tutorial: Route Summarization Plus the OSPF Null Interface
CCNP Test good results, significantly within the BSCI Test, needs you have an understanding of the small print of route summarization. This skill not simply calls for that you have a consolation level with binary conversions, but You should know how and where to apply route summarization with Every personal protocol.
You also have to learn the “Unwanted effects” of route summarization. With OSPF, there will basically be an extra interface produced at the point of summarization, which catches a great deal of CCNP candidates abruptly. Let’s Look into the null0 interface And the way it pertains to OSPF summarization.
On R1, the subsequent networks are redistributed into 토토사이트 OSPF, after which summarized.
interface Loopback16
ip handle sixteen.sixteen.16.16 255.0.0.0
interface Loopback17
ip handle seventeen.seventeen.seventeen.seventeen 255.0.0.0
interface Loopback18
ip handle 18.eighteen.eighteen.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 connected subnets
R1(config-router)#summary-deal with sixteen.0.0.0 252.0.0.0
The summary deal with appears on R2, a downstream router.
R2#demonstrate ip route ospf
O E2 16.0.0.0/six [a hundred and ten/20] by using 172.twelve.123.one, 00:00:05, Serial0
Allow’s go back to R1 and evaluate its OSPF desk.
R1#display ip route ospf
O 16.0.0.0/6 is a summary, 00:01:51, Null0
The place did the null0 interface originate from, and why can it be there? Packets sent for the null interface are dropped, and In this instance, that’s a great detail.
After you configure summary routes in OSPF, a route to null0 are going to be set up into the OSPF routing desk. This helps to prevent routing loops. Any packets destined to the routes that were summarized will likely have an extended match within the routing table, as shown down below…
C 17.0.0.0/8 is specifically connected, Loopback17
C 16.0.0.0/8 is straight related, Loopback16
C 19.0.0.0/8 is instantly related, Loopback19
C 18.0.0.0/8 is directly connected, Loopback18
O 16.0.0.0/6 is usually 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 likely be dropped.
Stopping routing loops when doing route redistribution and summarization is significant. OSPF offers us slightly help in that regard in this case, and while you study more sophisticated redistribution eventualities on the way to the CCNP and CCIE, you’ll understand that we’ll take all the assistance we might get!