CCNP / BSCI Exam Tutorial: Route Summarization As well as OSPF Null Interface
CCNP exam achievements, significantly on the BSCI Examination, needs you realize the small print of route summarization. This ability don't just needs you have a ease and comfort degree with binary conversions, but It's important to know how and where by to use route summarization with Each and every individual protocol.
You even have to understand the “side effects” of route summarization. With OSPF, there will essentially be an extra interface created at the point of summarization, and this catches lots of CCNP candidates abruptly. Enable’s Have a look at the null0 interface And exactly how 토토 it relates to OSPF summarization.
On R1, the subsequent networks are redistributed into OSPF, and afterwards summarized.
interface Loopback16
ip deal with sixteen.sixteen.sixteen.sixteen 255.0.0.0
interface Loopback17
ip tackle 17.seventeen.seventeen.seventeen 255.0.0.0
interface Loopback18
ip handle 18.eighteen.18.18 255.0.0.0
interface Loopback19
ip handle 19.19.19.19 255.0.0.0
R1(config)#router ospf 1
R1(config-router)#redistribute related subnets
R1(config-router)#summary-handle sixteen.0.0.0 252.0.0.0
The summary tackle appears on R2, a downstream router.
R2#clearly show ip route ospf
O E2 16.0.0.0/six [110/20] by using 172.12.123.1, 00:00:05, Serial0
Permit’s return to R1 and evaluate its OSPF table.
R1#present ip route ospf
O sixteen.0.0.0/six is actually a summary, 00:01:51, Null0
Wherever did the null0 interface originate from, and why could it be there? Packets sent into the null interface are dropped, and In this instance, that’s a great point.
When you configure summary routes in OSPF, a path to null0 will probably be installed into your OSPF routing desk. This allows to prevent routing loops. Any packets destined for the routes that were summarized could have an extended match from the routing table, as shown beneath…
C 17.0.0.0/eight is instantly connected, Loopback17
C 16.0.0.0/eight is right connected, Loopback16
C 19.0.0.0/eight is instantly related, Loopback19
C eighteen.0.0.0/8 is straight connected, Loopback18
O sixteen.0.0.0/six is usually a summary, 00:01:51, Null0
.. and packets that do not match among the summarized routes but do match the summary route will probably be dropped.
Protecting against routing loops when carrying out route redistribution and summarization is vital. OSPF gives us a bit assist in that regard in this situation, and when you research a lot more advanced redistribution scenarios on your own solution to the CCNP and CCIE, you’ll understand that we’ll take all the assistance we may get!