CCNP / BSCI Exam Tutorial: Route Summarization As well as OSPF Null Interface
CCNP Test results, specially http://query.nytimes.com/search/sitesearch/?action=click&contentCollection®ion=TopBar&WT.nav=searchWidget&module=SearchSubmit&pgtype=Homepage#/토토사이트 around the BSCI exam, demands you recognize the small print of route summarization. This talent not simply involves that you've a ease and comfort stage with binary conversions, but You must know the way and in which to apply route summarization with Just about every individual protocol.
You also have to understand the “Uncomfortable side effects” of route summarization. With OSPF, there'll really be an additional interface established at The purpose of summarization, and this catches many CCNP candidates by surprise. Allow’s Look into the null0 interface And the way it pertains to OSPF summarization.
On R1, the subsequent networks are redistributed into OSPF, after which you can summarized.
interface Loopback16
ip deal with sixteen.sixteen.sixteen.16 255.0.0.0
interface Loopback17
ip 토토 deal with seventeen.17.seventeen.seventeen 255.0.0.0
interface Loopback18
ip deal with 18.18.eighteen.18 255.0.0.0
interface Loopback19
ip address 19.19.19.19 255.0.0.0
R1(config)#router ospf 1
R1(config-router)#redistribute related subnets
R1(config-router)#summary-deal with 16.0.0.0 252.0.0.0
The summary address seems on R2, a downstream router.
R2#demonstrate ip route ospf
O E2 16.0.0.0/six [110/20] through 172.12.123.one, 00:00:05, Serial0
Enable’s return to R1 and have a look at its OSPF table.
R1#display ip route ospf
O 16.0.0.0/six is really a summary, 00:01:fifty one, Null0
Where did the null0 interface originate from, and why is it there? Packets sent to your null interface are dropped, and In such cases, that’s a fantastic factor.
Whenever you configure summary routes in OSPF, a path to null0 will likely be set up in the OSPF routing desk. This can help to circumvent routing loops. Any packets destined for your routes that have been summarized should have a longer match within the routing table, as proven below…
C seventeen.0.0.0/8 is specifically linked, Loopback17
C 16.0.0.0/8 is directly connected, Loopback16
C 19.0.0.0/8 is instantly linked, Loopback19
C 18.0.0.0/eight is immediately related, Loopback18
O 16.0.0.0/six is often a summary, 00:01:51, Null0
.. and packets that don't match on the list of summarized routes but do match the summary route will likely be dropped.
Preventing routing loops when performing route redistribution and summarization is significant. OSPF provides us slightly help in that regard in this example, and when you examine more complicated redistribution scenarios with your strategy to the CCNP and CCIE, you’ll know that we’ll take all the help we will get!