CCNP / BSCI Test Tutorial: Route Summarization And also the OSPF Null Interface
CCNP Test success, particularly over the BSCI Test, calls for you recognize the small print of route summarization. This skill don't just calls for that you've a convenience level with binary conversions, but you have to know the way and wherever to use route summarization with each specific protocol.
You even have to know the “Uncomfortable side effects” of route summarization. With OSPF, there will essentially be an extra interface produced at the point of summarization, which catches plenty of CCNP candidates unexpectedly. Permit’s take a look at the null0 interface and how it pertains to OSPF summarization.
On R1, the next networks are redistributed into OSPF, and then summarized.
interface Loopback16
ip address sixteen.sixteen.16.16 255.0.0.0
interface Loopback17
ip address 17.seventeen.seventeen.seventeen 255.0.0.0
interface Loopback18
ip tackle 18.18.eighteen.eighteen 255.0.0.0
interface Loopback19
ip deal with 19.19.19.19 255.0.0.0
R1(config)#router ospf 1
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#demonstrate ip route ospf
O E2 16.0.0.0/6 [110/twenty] by way of 172.12.123.1, 00:00:05, Serial0
Allow’s go back to R1 and check out its OSPF desk.
R1#demonstrate ip route ospf
O 16.0.0.0/6 can be a summary, 00:01:51, Null0
Where did the null0 interface originate from, and why could it be there? Packets sent towards the null interface are dropped, and In such cases, that’s a great point.
After you configure summary routes in OSPF, a path to null0 will probably be put in to the OSPF routing desk. This allows to prevent routing loops. Any packets destined for that routes that were summarized could have a longer match in the routing table, as demonstrated underneath…
C 17.0.0.0/eight is immediately linked, Loopback17
C 16.0.0.0/eight is right connected, Loopback16
C 19.0.0.0/eight is immediately related, Loopback19
C eighteen.0.0.0/eight is directly 토토사이트 connected, Loopback18
O sixteen.0.0.0/six can be a summary, 00:01:fifty one, Null0
.. and packets that do not match on the list of summarized routes but do match the summary route is going to be dropped.
Blocking routing loops when carrying out route redistribution and summarization is significant. OSPF presents us a little bit help in that regard in this case, and while you study additional elaborate redistribution eventualities on the technique to the CCNP and CCIE, you’ll understand that we’ll acquire all the help we will get!