CCNP / BSCI Exam Tutorial: Route Summarization And also the OSPF Null Interface
CCNP Test success, notably about the BSCI exam, demands you realize the details of route summarization. This ability not just calls for you have a consolation amount with binary conversions, but you have to know how and in which to apply route summarization with Just about every individual protocol.
You also have to find out the “Uncomfortable side effects” of route summarization. With OSPF, there'll truly be an additional interface created at the point of summarization, which catches a lot of CCNP candidates by surprise. Let’s Have a look at the null0 interface and how it pertains to OSPF summarization.
On R1, the next networks are redistributed into OSPF, then summarized.
interface Loopback16
ip tackle 16.sixteen.16.16 255.0.0.0
interface Loopback17
ip address seventeen.seventeen.seventeen.17 255.0.0.0
interface Loopback18
ip address 18.18.eighteen.eighteen 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-deal with 16.0.0.0 252.0.0.0
The summary handle appears on R2, a downstream router.
R2#present ip route ospf
O E2 sixteen.0.0.0/6 [a hundred and ten/20] by way of 172.12.123.1, 00:00:05, Serial0
Enable’s return to R1 and check out its OSPF desk.
R1#clearly show ip route ospf
O 16.0.0.0/six is often a summary, 00:01:fifty one, Null0
In which did the null0 interface come from, and why is it there? Packets despatched to your null interface are dropped, and in this case, that’s a great factor.
Once you configure summary routes in OSPF, a route to null0 will likely be 토토 set up into the OSPF routing table. This allows to forestall routing loops. Any packets destined for your routes which were summarized should have a http://query.nytimes.com/search/sitesearch/?action=click&contentCollection®ion=TopBar&WT.nav=searchWidget&module=SearchSubmit&pgtype=Homepage#/토토사이트 longer match while in the routing desk, as proven below…
C seventeen.0.0.0/8 is directly linked, Loopback17
C sixteen.0.0.0/eight is specifically related, Loopback16
C 19.0.0.0/8 is straight related, Loopback19
C 18.0.0.0/eight is specifically linked, 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 are going to be dropped.
Avoiding routing loops when doing route redistribution and summarization is significant. OSPF gives us somewhat help in that regard in this example, and while you study far more intricate redistribution eventualities on your strategy to the CCNP and CCIE, you’ll realize that we’ll acquire all the assistance we might get!