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Bronze

ppp and ripv2

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.

8 ACCEPTED SOLUTIONS

Accepted Solutions
Hall of Fame Super Blue

Re: ppp and ripv2

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

Hall of Fame Super Bronze

Re: ppp and ripv2

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.

Hall of Fame Super Bronze

Re: ppp and ripv2

It's not a bad design scenario when you are forced to preserve IP addressing space and rely on 'ip unnumbered' on WAN interfaces.

Re: ppp and ripv2

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

Re: ppp and ripv2

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

Hall of Fame Super Blue

Re: ppp and ripv2

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

Hall of Fame Super Bronze

Re: ppp and ripv2

That's the 'peer neighbor-route' knob that is enabled by default on PPP interfaces.

Re: ppp and ripv2

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.

10 REPLIES
Hall of Fame Super Blue

Re: ppp and ripv2

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

Re: ppp and ripv2

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.

Hall of Fame Super Bronze

Re: ppp and ripv2

It's not a bad design scenario when you are forced to preserve IP addressing space and rely on 'ip unnumbered' on WAN interfaces.

Hall of Fame Super Blue

Re: ppp and ripv2

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

Bronze

Re: ppp and ripv2

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 :-)

Hall of Fame Super Bronze

Re: ppp and ripv2

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.

Re: ppp and ripv2

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

Re: ppp and ripv2

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

Hall of Fame Super Bronze

Re: ppp and ripv2

That's the 'peer neighbor-route' knob that is enabled by default on PPP interfaces.

Re: ppp and ripv2

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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