RE: OSPF Summary 'range'

From: Brian Dennis (brian@labforge.com)
Date: Tue Jun 17 2003 - 16:15:37 GMT-3


First off we need to know what area the other routers are in. You can
not use the area range command to summarize routes to other OSPF routers
in the same area.

As far as the null0 route not being on R7 why would you want it to be
pointing to null0 on R7? If R5 is advertising the route and R7 has it
pointing to null0 how can R7 ever send traffic for the summary to R5?

Brian Dennis, CCIE #2210 (R&S/ISP-Dial/Security)

-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Jason Cash
Sent: Tuesday, June 17, 2003 11:38 AM
To: ccielab@groupstudy.com
Subject: OSPF Summary 'range'

Please explain..

IPE Topo

R2(s0)-----R5(s0)

       |

       |R6(s1/0)

Router 5,6,7 share common Ethernet.

R2

s0 172.29.100.2/28

R5

s0 172.29.100.5/28

e0 172.29.200.5/25

R6

s0 172.29.100.5/28

e0 172.29.200.6/25

R7

e0 172.29.200.7/25

s0 172.29.78.1/30

I setup a summary-address on R5 'area 0 range 172.29.200.0
255.255.255.0'
but that summary address is not showing up on R2 or R6.

However, the summary address on R7 is showing up on R2:

r2#si ospf | inc 78.0

O IA 172.29.78.0/24 [112/138] via 172.29.100.5, 00:38:51, Serial0.100

r5#si ospf | inc Null

O 172.29.200.0/24 is a summary, 00:33:48, Null0

I guess my question is, why doesn't the summary from R5 propagate to R2,
R6?
In redistribution (on R2 mutual RIP/OSPF) it appears that the only way
to
get these routes into RIP as to assign

the 'range' on R2 like the solution advises. Assuming I got that
summarized
172.29.200.0/24 route to R2, why would it not redist. That into OSPF?

Also, why is a Null0 route inserted on R5 and not on R7? If anyone has a
link to explain this, it would be much appreciated!

Configs:

R2

router ospf 1

 log-adjacency-changes

 area 0 authentication message-digest

 area 0 range 172.29.100.0 255.255.255.0

 area 12 range 172.29.12.0 255.255.255.0

 area 12 virtual-link 192.168.1.1 authentication

 area 12 virtual-link 192.168.1.1 message-digest-key 1 md5 ipexpert

 redistribute rip subnets route-map rip2ospf

 network 172.29.12.0 0.0.0.63 area 12

 network 172.29.25.0 0.0.0.255 area 0

 network 172.29.100.0 0.0.0.7 area 0

 network 192.168.2.2 0.0.0.0 area 2

 neighbor 172.29.100.5

 neighbor 172.29.100.6

 distance ospf inter-area 112 external 114

R5

router ospf 1

 log-adjacency-changes

 area 0 authentication message-digest

 area 0 range 172.29.200.0 255.255.255.0

 network 172.29.25.0 0.0.0.255 area 0

 network 172.29.100.0 0.0.0.7 area 0

 network 172.29.200.0 0.0.0.127 area 0

 network 192.168.5.5 0.0.0.0 area 5

R7

router ospf 1

 area 0 authentication message-digest

 area 78 nssa default-information-originate

 area 78 range 172.29.78.0 255.255.255.0

 redistribute connected subnets route-map loop

 network 172.29.78.0 0.0.0.3 area 78

 network 172.29.200.0 0.0.0.127 area 0



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