Cisco 887 ADSL connection problem

[Piotr Kowalczyk]

Hi

I have problem with Cisco 887 and ADSL connection and wonder if somebody can advice something. It is new installed device and was working fine for last 2 weeks. Today got a call from the site about internet problem so tried to get access to router and wasn’t able. Asked them to reboot and it started to work – unfortunately wasn’t able to get access to the device when it was down.

Called ISP and was told, no problem on their site, they were able to see on their logs the device was down since 9pm yesterday. As I don’t have logging server not able to check this on our site.

Do you know about any setting which may affect the ADSL connection this way? Please find config below:

interface ATM0

no ip address

no ip redirects

no ip unreachables

no ip proxy-arp

ip flow ingress

no atm ilmi-keepalive

!

interface ATM0.1 point-to-point

description $ES_WAN$$FW_OUTSIDE$

ip flow ingress

pvc 8/35

pppoe-client dial-pool-number 1

!

interface Dialer0

description $FW_OUTSIDE$

ip address negotiated

no ip redirects

no ip unreachables

no ip proxy-arp

ip mtu 1452

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 ***********

ppp chap password 7 *****************

ppp pap sent-username *********** password 7 ************

no cdp enable

crypto map SDM_CMAP_1

[mavespig · Accepted solution]

Hello Piotr,

Perhaps the DSL line has a bad signal. Can you collect the output of show dsl interface atm 0?

You should mainly focus on noise margin and attenuation.

Noise Margin: the higher the better. Under 8db the line with flap or it won't train up at all. Good values are over 14 db.

Attenuation: the lower the better. Over 60 you will have signal problems, better stay under 40.

Hope this helps

Marco

[Piotr Kowalczyk]

Marko,

Many thanks for your reply. Could you advise which value should I look at? ATU-R or ATU-C?

What is a difference between them?

Once again many thanks for your help.

                          ATU-R (DS)                      ATU-C (US)

Noise Margin:         21.5 dB                          7.0 dB

Attenuation:            23.0 dB                         10.5 dB

[Leo Laohoo · Accepted solution]

DS stands for Down Stream and US stands for Up Stream.

ATU stands for ADSL Terminating Unit.  R stands for Remote and C stands for I-forgot-what-C-stands-for.

Attenuation doesn't look good.  You want a very low number.  The Noise Margin is OK.

[David Santos · Accepted solution]

7.0 dB in the noise margin is not a good thing.And by the values of your attenuation you are a little bit far from the CO.

You have to talk to your ISP.

[Piotr Kowalczyk]

Marco, leolaohoo, David,

Many thanks for your profesional help. I will talk to ISP than.