From: Jason Cash (cash2001@swbell.net)
Date: Thu Jun 19 2003 - 18:58:31 GMT-3
The code on R5 is 12.1(20), and R7 is 12.1(5)T
_____
From: Hossam Mahmoud [mailto:sam6626@yahoo.com]
Sent: Wednesday, June 18, 2003 7:38 AM
To: Jason Cash; 'Brian Dennis'; ccielab@groupstudy.com
Jason,
1) For your first question, please note that as an OSPF general rule, a
summary route is propagated away form the area that has its detailed routes.
when you are summarizing for area 0 then you have to do it on all Backbpone
routers (i.e. routers with any interface on area 0) to ensure that yr
summary will be propagated to all areas.
So in your case you need to put the :
area 0 range 172.29.200.0 255.255.255.0
on all R2, R5, R6, R7 to ensure that your sumary is propagated to all your
routers/areas.
______________________________
2) For yr note about having the summary :
172.29.78.0 255.255.255.0 on R2
Please notice that
area 78 range 172.29.78.0 255.255.255.0 command on R7 is for area 78 (not
area 0) so it is logical to be propagated to all routers not only R2
____________________________
3) As for the second question. let me first rephrase it to ensure commen
understanding. I think your question was
why do R5 shows a null route for
area 0 range 172.29.200.0 255.255.255.0 command
while R7 does't show a null route for
area 78 range 172.29.7.0 255.255.255.0??
If that was yr question then :
As far as i know, intially OSPF was not creating a NULL router to its
summaries. It was recommended that we do this NULL route manually.
So i see R7 attitude as more logic.
Brain,
Did this chage? what version does yr R5 run??
Does OSPF now do this Null route automaticlly as EIGRP Does?? IF yes...Since
which version
Thanks,
SAM
Jason Cash <cash2001@swbell.net> wrote:
Both the Ethernet and Serial interfaces on R5,R6 are in A0
Serial on R2 - Area 0
Serial R7 - Area 7
Ethernet R7 Area 0
I am confused as to how summary addresses propagate. R2 would not redist.
Or even receive the 'area 0 range 172.29.200.0 255.255.255.0' from R5. So
the solution had that command inserted on R2 (which redistributes to R4 via
RIP). This is IPE Section 29.
What confuses me is why have the 'area range' command on R5 and 6?
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Brian Dennis
Sent: Tuesday, June 17, 2003 2:16 PM
To: 'Jason Cash'; ccielab@groupstudy.com
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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