Cisco 877 with Demon Broadband - Help

I am trying toget a Cisco 877 router working on my Demon B'band connection. The Broadband works when I use a BT Voyager 220V so I know the service itself is OK. The configuration on the router works quite happily when attached to a standard BT B'band connection at another site.

The ATM0 link comes up and then drops a few moments later. The CD led lights up followed by a limited amount of activity on both RXD and TXD leds and then the whole cycle appears to repeat itself,

I am not au fait with debugging as ar as the adsl link goes.

Can anyone help/advise.

Many Thanks,

Config is shown below

version 12.4

no service pad

service timestamps debug uptime

service timestamps log uptime

service password-encryption


hostname nnnnnnnn





logging buffered 40960 debugging

enable password password


no aaa new-model


resource policy


ip subnet-zero

ip cef


interface ATM0

no ip address

no atm ilmi-keepalive

pvc 0/38

encapsulation aal5mux ppp dialer

dialer pool-member 1


dsl operating-mode auto


interface FastEthernet0


interface FastEthernet1


interface FastEthernet2


interface FastEthernet3


interface Vlan1

description #Connection to Home LAN#

ip address 192.168.n.n

ip nat inside

ip virtual-reassembly

ip tcp adjust-mss 1452


interface Dialer1

ip address negotiated

ip nat outside

ip virtual-reassembly

encapsulation ppp

dialer pool 1

ppp chap hostname

ppp chap password nnnnnnnn


ip classless

ip route Dialer1


no ip http server

no ip http secure-server

ip nat inside source list 1 interface Dialer1 overload


access-list 1 permit




line con 0

no modem enable

line aux 0

line vty 0

password nnnnnnn


line vty 1 4



scheduler max-task-time 5000


Reply to
Colin Heseltine
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On 877 I have seen various DSL issues (but not your one). Worth trying

int atm 0 dsl operating-mode {all possibilities one by one} ! There are only a few:-)

Worth an IOS software upgrade too if you have support.

Otherwise you may consider:- DSL firmware can be downloaded from Don't worry too much where it says the firmware release only supports a particular IOS - give it a try anyway.

Reply to

Neither am I but this might help, if you haven't already read it.



I'm not using Demon but my 877 has a slightly different configuration. I have an ATM0.1 (sub) interface. I'd guess it isn't a significant difference but you might try it

interface ATM0 no ip address no ip redirects no ip unreachables no ip proxy-arp ip route-cache flow no atm ilmi-keepalive dsl operating-mode auto ! interface ATM0.1 point-to-point pvc 0/38 encapsulation aal5mux ppp dialer dialer pool-member 1 ! !


interface Dialer0 ip address negotiated ip access-group 101 in no ip redirects no ip unreachables no ip proxy-arp ip inspect DEFAULT100 out ip nat outside ip virtual-reassembly encapsulation ppp ip route-cache flow dialer pool 1 dialer-group 1 no cdp enable ppp authentication chap callin ppp chap hostname xxxxxxxxxxxxxxxx ppp chap password 7 xxxxxxxxxxxxxxxxxxxx !

You'd obviously need to prune out the ACL references. The only other significant difference might be the omission of the 'ppp authentication chap callin' line?

You could also try saving your current config somewhere safe (e.g. TFTP server) and using SDM to generate a new config.

Caveat: I'm new to Cisco and not an expert.

Reply to
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