Moving the internet line

[Vishnu Reddy]

Hello Guys,

We have a Ciso 2911 as WAN router for MPLS and Yamaha router for internet at the Japan site. This site gets internet through Yamaha router and its an Ethernet handoff.

Ciso router has the default pointing to Yamaha for going to internet. Now the plan is to move the Internet from Yamaha router to Cisco router. Tested this by removing the ethernet cable and plugging it into cisco 2911 router and setting the default point to the ISP for internet.

int g0/2

ip address a.b.c.240 255.255.255.252

ip route 0.0.0.0 0.0.0.0 a.b.c.249

Ping doesn;t work getting request timed out.

My question is should the ping work automatically without involving the ISP. should we need to contact the ISP for any changes we are making at our end. Its an ethernet handoff. Since this is my first time I am not aware what are the bits and pieces that go into to make it working.

Thanks in advance.

[Jon Marshall]

The ISP will have the incorrect mac address to IP mapping at their end when you switch the connection.

So they will be using the mac address of the Yamaha router for the IP a.b.c.240 whereas the actual mac address is the gi0/2 interface on your Cisco router.

Basically you need to the ISP to clear the arp entry for that IP at their end or wait for it to timeout but that depends on how long their settings are.

Jon

[Vishnu Reddy · Accepted solution]

Thanks for your reply. Same this was going on my mind but was not sure that this would be case. I will work towards updating the ISPs mac address to get this going on and will update here the next steps about resolution.

Appreciate your response. Thank you.

[paul driver]

Hello

I guess yoi could also spoof the mac of the old router

int g0/2
mac address xxxx.xxxx.xxxx

res

Pau

[Vishnu Reddy]

Tried that. Didn't work out. I am guessing since its ethernet handoff all the switches on the path or may have to learn through conventional discovery process and also have to find out whats the arp timeout configured at the ISP end.

[Richard Burts]

What strikes me about this is the mismatch between the next hop in the default route and the subnet/address of the interface.

ip address a.b.c.240 255.255.255.252

ip route 0.0.0.0 0.0.0.0 a.b.c.249

The next hop in the default route is not in the subnet of the outside interface. I also note that with mask of 255.255.255.252 that .240 is not a valid host address.

HTH

Rick

[Vishnu Reddy]

Thanks for your reply.

I guess I mistyped. Actually in the interest of revealing the actual IP address I have to come of with some other IP.

Here's the local IP address: x.y.z.250/30

And the remote end IP address is x.y.z.249/30.

ip route 0.0.0.0 0.0.0.0 x.y.z.249

I guess the ISP is using the static arp since its still now working.

[Richard Burts]

Thanks for clarifying that it was a typo. Yes if the interface is .250 and the ISP is .249 that does have them both in the same subnet and then your static default route would be right.

I am glad to hear that it now is working.

HTH

Rick

[Vishnu Reddy]

Its still not working. Sorry about that mistyping.

ISP said moving the cable to another router does not make any problem as   confirmed by ISP this morning.

Not sure what could be the problem. I had this static default route pointing to ISP.

Guys, Any ideas what additional configuration that needs to be done from my end of the router.

Thanks in advance.

[Richard Burts]

Sorry to hear that it is not working. It is hard to know at this point what the problem is. Would you please post the output of these commands

show ip interface brief

show arp

show ip route

Hopefully these will give us some insight into the problem.

HTH

Rick

[Vishnu Reddy]

Thanks for the reply. We reverted back the setting to point to the Yamaha router since we can't do that in business hours. I will get the output next weekend.

Thank you.