Cisco router 800 series interface cellular0 keeps bouncing up/down

[tinhnho123]

Hi Everyone,

I was able to setup my router c819 with Verizon 3G but there is one minor thing that on the console it keeps saying:

Aug  7 21:04:30.067: %LINK-5-CHANGED: Interface Cellular0, changed state to reset

Aug  7 21:04:35.111: %LINK-3-UPDOWN: Interface Cellular0, changed state to down

Aug  7 21:06:18.423: %LINK-3-UPDOWN: Interface Cellular0, changed state to up

The interface Cellluar0 is connected to Verizon 3G network and I'm able to ping and get to the internet just fine. I did few research and some people said it was access list. My ACL is below but I can't find anything wrong with it. Any ideas?

!

!

interface Cellular0

ip address negotiated

ip nat outside

ip virtual-reassembly in

encapsulation ppp

dialer in-band

dialer string cdma

dialer-group 1

async mode interactive

ppp chap password 0 cisco

!

!

access-list 1 permit any

dialer-list 1 protocol ip list 1

!

Thanks.

[tinhnho123]

When the route is sitting idle, I see the interface cell 0 bouncing up and down. But when I'm ping 8.8.8.8 (or other external ip addresses), I don't see the interface cell 0 bouncing. Any ideas?

[Kristian Alexander Brown]

My only guess would be that the cellular connection times out when its idle too long. Atleast that was my problem at home. I fixed it with ip sla configured with icmp-echo to an external address reachable through the cellular interface. 1 packet each 10 seconds should be enough.

Regards,

Kristian

Sent from Cisco Technical Support iPhone App

[tinhnho123]

Hi,

Just curiosity, for the fix how do you get that setup on your router?

Thanks.

[Kristian Alexander Brown]

Hi,

Try something like this:

ip sla 1

icmp-echo 8.8.8.8 source-interface Cellular0

frequency 10

ip sla schedule 1 life forever start-time now

It will however only work if you actually have a valid route in the routers RIB pointing traffic (icmp) towards 8.8.8.8 out interface Cellular0. If you dont, choose an ip address that does. (or use a static route towards a /32 prefix aka host)

Also, you may need to change "source-interface Cellular0" to your LAN interface, depending on your router config.

Regards,

Kristian