CCNP / BSCI Exam Tutorial: Route Summarization As well as OSPF Null 먹튀 Interface
CCNP Test achievements, specifically about the BSCI Examination, needs you realize the main points of route summarization. This skill not only needs you have a ease and comfort amount with binary conversions, but you have to know how and the place to apply route summarization with Every single personal protocol.
You even have to understand the “Unwanted effects” of route summarization. With OSPF, there'll in fact be an additional interface made at the point of summarization, and this catches lots of CCNP candidates without warning. Enable’s Have a look at the null0 interface and how it pertains to OSPF summarization.
On R1, the following networks are redistributed into OSPF, and then summarized.
interface Loopback16
ip address sixteen.sixteen.sixteen.sixteen 255.0.0.0
interface Loopback17
ip tackle 17.17.seventeen.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 one
R1(config-router)#redistribute connected subnets
R1(config-router)#summary-tackle 16.0.0.0 252.0.0.0
The summary handle seems on R2, a downstream router.
R2#clearly show ip route ospf
O E2 sixteen.0.0.0/6 [one hundred ten/twenty] through 172.twelve.123.one, 00:00:05, Serial0
Let’s return to R1 and evaluate its OSPF table.
R1#demonstrate ip route ospf
O sixteen.0.0.0/six can be a summary, 00:01:fifty one, Null0
Wherever did the null0 interface come from, and why is it there? Packets sent to the null interface are dropped, and In this instance, that’s a fantastic factor.
When you configure summary routes in OSPF, a route to null0 will likely be put in into your OSPF routing table. This can help to prevent routing loops. Any packets destined for the routes that have been summarized will have an extended match inside the routing desk, as demonstrated underneath…
C 17.0.0.0/8 is right related, Loopback17
C sixteen.0.0.0/eight is right related, Loopback16
C 19.0.0.0/8 is immediately related, Loopback19
C eighteen.0.0.0/eight is instantly related, Loopback18
O 16.0.0.0/6 is a summary, 00:01:fifty one, Null0
.. and packets that do not match one of the summarized routes but do match the summary route are going to be dropped.
Stopping routing loops when undertaking route redistribution and summarization is vital. OSPF gives us just a little assist in that regard in this example, and when you examine extra intricate redistribution situations on the strategy to the CCNP and CCIE, you’ll recognize that we’ll take all the help we might get!