CCNP / BSCI Examination Tutorial: Route Summarization As well as OSPF Null Interface
CCNP Test success, particularly on the BSCI Examination, calls for you have an understanding of the main points of route summarization. This ability not just requires that you have a comfort and ease level with binary conversions, but you have to understand how and wherever to apply route summarization with Every single person protocol.
You even have to find out the “Unwanted effects” of route summarization. With OSPF, there will in fact be an extra interface designed at The purpose of summarization, which catches a lot of CCNP candidates abruptly. Permit’s Check out the null0 interface And the way it relates to OSPF summarization.
On R1, the subsequent networks are redistributed into OSPF, after which you can summarized.
interface Loopback16
ip address sixteen.sixteen.16.16 255.0.0.0
interface Loopback17
ip tackle seventeen.17.17.seventeen 255.0.0.0
interface Loopback18
ip tackle eighteen.18.18.18 255.0.0.0
interface Loopback19
ip tackle 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 handle appears on R2, a downstream router.
R2#present ip route ospf
O E2 sixteen.0.0.0/6 [110/20] through 172.12.123.one, 00:00:05, Serial0
Allow’s return to R1 and examine its OSPF desk.
R1#demonstrate ip route ospf
O 16.0.0.0/six is usually a summary, 00:01:fifty one, Null0
Wherever did the null0 interface originate from, and why is it there? Packets sent towards the null interface are dropped, and in this case, that’s a very good matter.
Any time you configure summary routes in OSPF, a path to null0 will be installed into the OSPF routing table. This assists to circumvent routing loops. Any packets destined for that routes which were summarized should have a longer match in the routing table, as proven underneath…
C 17.0.0.0/eight is instantly linked, Loopback17
C sixteen.0.0.0/eight is instantly related, Loopback16
C 19.0.0.0/8 is specifically linked, 먹튀검증 Loopback19
C eighteen.0.0.0/eight is directly connected, Loopback18
O sixteen.0.0.0/6 is really a summary, 00:01:fifty one, Null0
.. and packets that don't match among the summarized routes but do match the summary route might be dropped.
Stopping routing loops when doing route redistribution and summarization is vital. OSPF offers us a little bit assist in that regard in this example, and when you examine a lot more sophisticated redistribution scenarios on your technique to the CCNP and CCIE, you’ll realize that we’ll get all the help we could get!