08-19-2009 03:40 PM - edited 03-06-2019 07:20 AM
Hi every body.
Let say we have a network
R1s0-----------------s0R2f0-----
I intentionally used two different subnet on so on both routers.
R1
int s0
10.10.10.1/24
encapsulation ppp
clockrate 56000
R2
int s0
ip address 10.10.11.1/24
encapsulation ppp
int fo
ip address 12.12.12.12/24
==============================
Ping on R1 to R2's0 will be successful.
Let say we enabled ripv2 on both routers. Will R2 be able to exchange routes on s0 with R1 as so int on both are in different subnet?
I am just wondering because ospf or eigrp won't exchange routes in the above case. But how about ripv2?
Thanks.
Solved! Go to Solution.
08-19-2009 03:54 PM
Sarah
No they can't exchange routes. Even though they do not form neighborships in the way EIGRP/OSPF do they still reject the routing update with the following message -
RIP: ignored V2 update from bad source - 10.10.10.1 on s0/0
the above was seen on R2 from your example.
Jon
08-19-2009 03:59 PM
With RIP you can actually accept routes without verifying the source IP but you have to turn off 'validate-update-source' which is enabled by default
http://www.cisco.com/en/US/docs/ios/iproute/command/reference/irp_rip.html#wp1012874
HTH,
__
Edison.
08-19-2009 04:01 PM
It's not a bad design scenario when you are forced to preserve IP addressing space and rely on 'ip unnumbered' on WAN interfaces.
08-19-2009 04:04 PM
actually the routing table will show it as directly connected anyway:
Gateway of last resort is not set
2.0.0.0/30 is subnetted, 1 subnets
C 2.2.2.0 is directly connected, FastEthernet0/1
10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C 10.10.11.1/32 is directly connected, Serial0/0/0:0
C 10.10.10.0/24 is directly connected, Serial0/0/0:0
So rip is not even in use in the ppp scenario between r1 and r2
08-19-2009 04:08 PM
To add, to that if you advertise other networks, you will observe what ediortiz said:
Before the command no validate-update-source:
*Aug 20 00:19:42.178: RIP: ignored v2 update from bad source 10.10.10.1 on Serial
AfteR:
IP: received v2 update from 10.10.10.1 on Serial0/0/0:0
And then the route gets installed, so yes it will work
08-19-2009 04:11 PM
Lucien
I don't think it's the book, rather this is the way Sarah learns ie. by reading the core stuff and then coming up with unusual scenarios to make sure she fully understands it.
And it keeps us all on out toes as well to be honest :-)
Jon
08-19-2009 04:15 PM
That's the 'peer neighbor-route' knob that is enabled by default on PPP interfaces.
08-19-2009 04:16 PM
correct, doesnt that remind you when you studied for ccie. it reminds me on the lab days. How to disable the route, turn off the neighbor-route.
08-19-2009 03:54 PM
Sarah
No they can't exchange routes. Even though they do not form neighborships in the way EIGRP/OSPF do they still reject the routing update with the following message -
RIP: ignored V2 update from bad source - 10.10.10.1 on s0/0
the above was seen on R2 from your example.
Jon
08-19-2009 03:55 PM
wondering why a book would keep on turning to you BAD design scenarios, not a good way to learn proper configs.
Actually this will work, look at the next posts for the debug outputs from my lab.
08-19-2009 04:01 PM
It's not a bad design scenario when you are forced to preserve IP addressing space and rely on 'ip unnumbered' on WAN interfaces.
08-19-2009 04:11 PM
Lucien
I don't think it's the book, rather this is the way Sarah learns ie. by reading the core stuff and then coming up with unusual scenarios to make sure she fully understands it.
And it keeps us all on out toes as well to be honest :-)
Jon
08-19-2009 06:00 PM
Thanks Jon and all of you.
Thanks to you guys and my stupid scenarios, i have learned a lot which i could not have learned by just reading books.
thanks all of you, see you again with more stupid questions :-)
08-19-2009 03:59 PM
With RIP you can actually accept routes without verifying the source IP but you have to turn off 'validate-update-source' which is enabled by default
http://www.cisco.com/en/US/docs/ios/iproute/command/reference/irp_rip.html#wp1012874
HTH,
__
Edison.
08-19-2009 04:04 PM
actually the routing table will show it as directly connected anyway:
Gateway of last resort is not set
2.0.0.0/30 is subnetted, 1 subnets
C 2.2.2.0 is directly connected, FastEthernet0/1
10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C 10.10.11.1/32 is directly connected, Serial0/0/0:0
C 10.10.10.0/24 is directly connected, Serial0/0/0:0
So rip is not even in use in the ppp scenario between r1 and r2
08-19-2009 04:08 PM
To add, to that if you advertise other networks, you will observe what ediortiz said:
Before the command no validate-update-source:
*Aug 20 00:19:42.178: RIP: ignored v2 update from bad source 10.10.10.1 on Serial
AfteR:
IP: received v2 update from 10.10.10.1 on Serial0/0/0:0
And then the route gets installed, so yes it will work
08-19-2009 04:15 PM
That's the 'peer neighbor-route' knob that is enabled by default on PPP interfaces.
08-19-2009 04:16 PM
correct, doesnt that remind you when you studied for ccie. it reminds me on the lab days. How to disable the route, turn off the neighbor-route.
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