CCNP / BSCI Examination Tutorial: Route Summarization Plus the OSPF Null Interface
CCNP Examination success, particularly over the BSCI Test, demands you comprehend the small print of route summarization. This skill not only necessitates that you've got a comfort and ease level with binary conversions, but You need to know how and exactly where to use route summarization with Each and every specific protocol.
You also have to understand the “Negative effects” of route summarization. With OSPF, there will basically be an extra interface produced at The purpose of summarization, and this catches plenty of CCNP candidates unexpectedly. Enable’s Examine the null0 interface and how it relates to OSPF summarization.
On R1, the following networks are redistributed into OSPF, and then summarized.
interface Loopback16
ip address 16.sixteen.sixteen.16 255.0.0.0
interface Loopback17
ip handle 17.17.17.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 one
R1(config-router)#redistribute linked subnets
R1(config-router)#summary-deal with sixteen.0.0.0 252.0.0.0
The summary handle seems on R2, a downstream router.
R2#exhibit ip route ospf
O E2 16.0.0.0/6 [110/twenty] by using 172.12.123.one, 00:00:05, Serial0
Permit’s go back to R1 and look at its OSPF table.
R1#clearly show ip route ospf
O sixteen.0.0.0/six is usually a summary, 00:01:51, Null0
Exactly where did the null0 interface http://www.bbc.co.uk/search?q=토토사이트 come from, and why can it be there? Packets despatched towards the null interface are dropped, and In this instance, that’s an excellent point.
After you configure summary routes in OSPF, a path to null0 are going to be mounted in the OSPF routing desk. This aids to prevent routing loops. Any packets destined for your routes which have been summarized could have a longer match during the routing table, as proven beneath…
C seventeen.0.0.0/8 is specifically linked, 먹튀검증 Loopback17
C sixteen.0.0.0/eight is specifically connected, Loopback16
C 19.0.0.0/8 is directly related, Loopback19
C eighteen.0.0.0/8 is straight linked, Loopback18
O sixteen.0.0.0/six is often a summary, 00:01:fifty one, Null0
.. and packets that don't match one of the summarized routes but do match the summary route are going to be dropped.
Protecting against routing loops when executing route redistribution and summarization is important. OSPF presents us somewhat help in that regard in this situation, and while you examine more intricate redistribution situations on your solution to the CCNP and CCIE, you’ll recognize that we’ll choose all the assistance we may get!