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external modem configuration


im attempting a lab to allow dial-backup in the even of a primary link failure. it is working fine but i wanted to find out if there was a way to allow the backup connection to detect the link failure and automatically dial using the backup interface. for instance object tracking on the interface i desire

New Member

Re: external modem configuration

Try searching Cisco's website for the "Dialer Watch" configuration parameters. Here's a brief description. Should work similarly for ISDN or POTS backups.



Re: external modem configuration


i have everything working so far. the issue now is that there is no consistency. i will get the automatic dialout when i down the primary interface, but when i connect the main interface again and bring it back down, the modem doesnt dial. debugs show that modem hangs up and is in idle state everytime

03:25:58: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/0, changed state to down

03:26:00: %LINK-3-UPDOWN: Interface Serial0/0, changed state to down

03:26:10: Se0/0 DDR: re-enable timeout

03:26:10: DDR: Dialer Watch: watch-group = 1

03:26:10: DDR: network DOWN,

03:26:10: DDR: network DOWN,

03:26:10: DDR: primary DOWN

03:26:10: Se0/0 DDR: Dialer Watch: resetting call in progress

03:26:10: Se0/0 DDR: Dialer Watch: Check reconnection needed

any ideas?

New Member

Re: external modem configuration

Sounds like the router portion is working as expected. Modems can be tricky. I've had similar problems in the past. Sounds like the modem is not configured properly. Perhaps it is not hanging up after it dials?

Does the modem dial and connect the first time that you down your primary connection? If it does, is it just that it fails the second time around?

Take a look at these modem AT codes which I found very helpful when I had to install dial up access:

You may want to reset the modem to factory default before changing any settings.

Let me know...



Re: external modem configuration

i was thinking along the same lines as well, but,

the inconsistency is for the automatic failover with the dialer watch only. if i issue a ping to the remote end the modem dials through fine all the time.

my configuration has a dialer watch for the primary link ip with a delay of 4. i have a all forward route to the remote location.

very simple, but its just not consistent

New Member

Re: external modem configuration

Do you have a config?

I use this to dial into a 3640.

interface Async5

ip address

encapsulation ppp

keepalive 10

dialer in-band

dialer idle-timeout 300

dialer string 9,xxxxxxxxxxx

dialer-group 1

fair-queue 64 16 0

ppp authentication chap

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