Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

New Member

ADSL Disconnects on 877 series routers

We have deployed a number of 800 series routers for some of our clients and have found that in many cases they seem to disconnect at an excessive rate. When I connected to the console of one the other day I could see that the virtual-interface for the ADSL connection was down, but not the ATM or DSL interface. If I disconnected the cable and reconnected the virtual-circuit came back up momentarily before disconnecting within a minute.

If I switched off the router for a few minutes and powered it back on it would usually remain up for a few hours. I reconfigured the router again using exactly the same config and it seemed to stay up for quite long periods for 4 or 5 days before reverting to type.

Although I cannot say for sure, when I have tested using other manufacturer modems I don't appear to have these problems.

Router firmware:c870-advsecurityk9-mz.124-24.T5.bin

ADSL firmware: AMR-E-4.0.018.bin

Relevant config details:

interface ATM0

no ip address

no ip redirects

no ip unreachables

no ip proxy-arp

ip flow ingress

no atm ilmi-keepalive

dsl bitswap both


interface ATM0.1 point-to-point

description <description>

no ip redirects

no ip unreachables

no ip proxy-arp

ip flow ingress

pvc 0/38

  encapsulation aal5mux ppp dialer

  dialer pool-member 1

interface Dialer0

description <description>

ip address negotiated

no ip redirects

no ip unreachables

no ip proxy-arp

ip flow ingress

ip nat outside

ip virtual-reassembly

zone-member security out-zone

encapsulation ppp

dialer pool 1

dialer-group 1

ppp authentication chap pap callin

ppp chap hostname <ADSL-Username>

ppp chap password <ADSL Password>

ppp pap sent-username <ADSL-Username> password <ADSL-Password>

crypto map <VPN>

If anyone could make some suggestions on how I could test or move forward I would be extermely grateful.

Hall of Fame Super Gold

Re: ADSL Disconnects on 877 series routers

You can troubleshoot  PPP level disconnections with "debug ppp negotiation".

Note if I would urgenlty update IOS and remove zone firewall command, that only slows down and do not provide any added security.

Re: ADSL Disconnects on 877 series routers

Hi Rob

what line is connected i have seen, that german telekom use somthing called Power Back off or dynamic spectrum management. This leed for us into some problems beacuse old routers do not support this.

You can ask your telco if they are using this. If telco provides VDSL / 25 Mbit/s + or outdoor dslam's are good sign ...

CreatePlease login to create content