Once in awhile my 871w loses the DSL connection and the Dialer0 interface goes down. When the atm0 interface comes up, sometimes the Dialer0 interface hangs for 5 minutes or so before redialing. Is there anything I can do to improve the connection time and reduce the downtime? Thanks.

interface Dialer0
 bandwidth 384
 bandwidth receive 2000
 ip address negotiated
 ip nat outside
 ip virtual-reassembly
 encapsulation ppp
 ip tcp adjust-mss 1452
 dialer pool 1
 dialer enable-timeout 1
 dialer wait-for-line-protocol 1
 dialer wait-for-carrier-time 1
 dialer redial interval 5 attempts 65535 re-enable 360
 dialer-group 1
 ppp authentication chap pap callin
 ppp chap hostname username
 ppp chap password 7 01234567890
 ppp pap sent-username username password 7 01234567890
 crypto map mymap
 service-policy output QoS-Output-Wrapper
  • Could you post a copy of the config from your CLI (if you have access)? I'm curious to see what your ppp keepalive is set to.
    – jackhamm
    Dec 26, 2011 at 6:58
  • Sure, post updated.
    – ensnare
    Dec 26, 2011 at 10:10
  • Related: what is your downstream noise margin, and have you tried reducing the downstream speed until it exceeds 12dB? You quite possibly may be able to achieve a stable connection at 1.5Mbps if you are "almost stable" at 2Mbps.
    – Skyhawk
    Dec 26, 2011 at 17:38
  • It's strange -- the noise margin is around 11db during the daytime and goes down to 1-2db at night. How can I force a slower speed? I already set dsl noise-margin 3 in the atm0 interface.
    – ensnare
    Dec 26, 2011 at 18:28

2 Answers 2


Your disable time is set to 6 minutes (360 seconds). You should try to disable the dialer redial option as you have already specified dialer wait-for-line-protocol.

Dialer should redial automatically as soon as both dsl sync (wait-for-carrier-time) and atm layer (wait-for-line-protocol) are up.

Try to do the following:

Router(config)# interface dialer0
Router(config-if)# no dialer redial interval 5 attempts 65535 re-enable 360

You could also increase the timeout on the wait-for option to see if line goes down again:

Router(config)# interface dialer0
Router(config-if)# dialer wait-for-line-protocol 5
Router(config-if)# dialer wait-for-carrier-time 5

Under interface Dialer0 try forcing PPP to timeout faster using:

keepalive 10 5

You may need to tweak the numbers, but here is the general command:

keepalive [seconds between ping] [max retries]

The easiest test will be to try adding the keepalive then down the interface and see how long it takes dialer0 to come back up - compare to the pre-keepalive time.


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