PPP problems with Eircom DSL Circuit and Cisco 887 Router

shanemoss · ‎07-11-2011

Hi folks,

I'm having problems with a 887 router connecting to Eircom DSL. This router was installed and has worked correctly for about a month or so until last Friday when no data could be passed across the DSL connection. Nothing changed on the Cisco router and Eircom claim that nothing has changed on their side (the circuit did come back up again on Friday evening with no changes being made on the 887 router but has since gone down again). If I replace the Cisco router with a Belkin or Netopia router the link comes up just fine. The DSL sync's up ok and PPP starts and CHAP is successful, the routing table shows the interface has come up, however no data appears to be routed correctly. A PPP packet debug shows the following, it looks like I have some sort of unidirectional PPP connection - we respond to an echo request but the far end doesn't appear to respond to our echo request - ultimatly the link is brought down (the dialer interface keepalive is set to 60 seconds). Can anyone please suggest anything that I can try? Thanks in advance,

*Jul 11 08:31:01.875: %LINK-3-UPDOWN: Interface ATM0, changed state to up

*Jul 11 08:31:02.875: %LINEPROTO-5-UPDOWN: Line protocol on Interface ATM0, changed state to up

*Jul 11 08:31:19.463: %DIALER-6-BIND: Interface Vi1 bound to profile Di0

*Jul 11 08:31:19.467: %LINK-3-UPDOWN: Interface Virtual-Access1, changed state to up

*Jul 11 08:31:19.467: Vi1 PPP: No remote authentication for call-out

*Jul 11 08:31:19.599: Vi1 PPP: I pkt type 0xC021, datagramsize 21 link[ppp]

*Jul 11 08:31:19.599: Vi1 PPP: I pkt type 0xC021, datagramsize 12 link[ppp]

*Jul 11 08:31:19.631: Vi1 PPP: I pkt type 0xC021, datagramsize 21 link[ppp]

*Jul 11 08:31:19.663: Vi1 PPP: I pkt type 0xC021, datagramsize 21 link[ppp]

*Jul 11 08:31:19.695: Vi1 PPP: I pkt type 0xC021, datagramsize 21 link[ppp]

*Jul 11 08:31:19.727: Vi1 PPP: I pkt type 0xC021, datagramsize 21 link[ppp]

*Jul 11 08:31:19.759: Vi1 PPP: I pkt type 0xC021, datagramsize 21 link[ppp]

*Jul 11 08:31:19.759: Vi1 LCP: Sent too many CONFNAKs. Switch to CONFREJ

*Jul 11 08:31:19.791: Vi1 PPP: I pkt type 0xC021, datagramsize 17 link[ppp]

*Jul 11 08:31:19.823: Vi1 PPP: I pkt type 0xC223, datagramsize 32 link[ppp]

*Jul 11 08:31:19.823: Vi1 CHAP: I CHALLENGE id 94 len 30 from "bbh2.bras"

*Jul 11 08:31:19.823: Vi1 CHAP: O RESPONSE id 94 len 38 from "

eircom@eircom.net

"

*Jul 11 08:31:20.099: Vi1 PPP: I pkt type 0xC223, datagramsize 6 link[ppp]

*Jul 11 08:31:20.099: Vi1 CHAP: I SUCCESS id 94 len 4

*Jul 11 08:31:20.107: %LINEPROTO-5-UPDOWN: Line protocol on Interface Virtual-Access1, changed state to up

*Jul 11 08:31:20.135: Vi1 PPP: I pkt type 0x8021, datagramsize 12 link[ip]

*Jul 11 08:31:20.175: Vi1 PPP: I pkt type 0x8021, datagramsize 12 link[ip]

*Jul 11 08:31:20.219: Vi1 PPP: I pkt type 0x8021, datagramsize 12 link[ip]

*Jul 11 08:31:22.215: Vi1 PPP: O pkt type 0x0021, datagramsize 68

*Jul 11 08:31:22.215: Vi1 PPP: O pkt type 0x0021, datagramsize 42

*Jul 11 08:31:23.207: Vi1 PPP: O pkt type 0x0021, datagramsize 68

*Jul 11 08:31:23.751: Vi1 PPP: O pkt type 0x0021, datagramsize 42

*Jul 11 08:31:24.207: Vi1 PPP: O pkt type 0x0021, datagramsize 68

*Jul 11 08:31:24.775: Vi1 PPP: O pkt type 0x0021, datagramsize 42

Cut for the sake of brevity - more of the same packets leaving router but nothing coming back

*Jul 11 08:32:19.047: Vi1 PPP: O pkt type 0x0021, datagramsize 42

*Jul 11 08:32:19.847: Vi1 LCP-FS: I ECHOREQ [Open] id 95 len 8 magic 0x3C3EE5F2

*Jul 11 08:32:19.847: Vi1 LCP-FS: O ECHOREP [Open] id 95 len 8 magic 0x011E1974

*Jul 11 08:32:20.119: Vi1 LCP: O ECHOREQ [Open] id 1 len 12 magic 0x011E1974

*Jul 11 08:32:20.583: Vi1 PPP: O pkt type 0x0021, datagramsize 42

*Jul 11 08:32:21.607: Vi1 PPP: O pkt type 0x0021, datagramsize 42

Cut for the sake of brevity - more of the same packets leaving router but nothing coming back

*Jul 11 08:33:17.951: Vi1 PPP: O pkt type 0x0021, datagramsize 68

*Jul 11 08:33:19.539: Vi1 PPP: O pkt type 0x0021, datagramsize 73

*Jul 11 08:33:19.947: Vi1 LCP-FS: I ECHOREQ [Open] id 96 len 8 magic 0x3C3EE5F2

*Jul 11 08:33:19.947: Vi1 LCP-FS: O ECHOREP [Open] id 96 len 8 magic 0x011E1974

*Jul 11 08:33:20.151: Vi1 LCP: O ECHOREQ [Open] id 2 len 12 magic 0x011E1974

*Jul 11 08:33:20.151: Vi1 LCP: echo_cnt 2, sent id 2, line up

*Jul 11 08:33:21.951: Vi1 PPP: O pkt type 0x0021, datagramsize 68

*Jul 11 08:33:23.539: Vi1 PPP: O pkt type 0x0021, datagramsize 73

*Jul 11 08:33:23.559: Vi1 PPP: O pkt type 0x0021, datagramsize 42

Cut for the sake of brevity - more of the same packets leaving router but nothing coming back

*Jul 11 08:34:18.407: Vi1 PPP: O pkt type 0x0021, datagramsize 73

*Jul 11 08:34:20.043: Vi1 LCP-FS: I ECHOREQ [Open] id 97 len 8 magic 0x3C3EE5F2

*Jul 11 08:34:20.043: Vi1 LCP-FS: O ECHOREP [Open] id 97 len 8 magic 0x011E1974

*Jul 11 08:34:20.183: Vi1 LCP: O ECHOREQ [Open] id 3 len 12 magic 0x011E1974

*Jul 11 08:34:20.183: Vi1 LCP: echo_cnt 3, sent id 3, line up

*Jul 11 08:34:20.199: Vi1 PPP: O pkt type 0x0021, datagramsize 68

*Jul 11 08:34:24.199: Vi1 PPP: O pkt type 0x0021, datagramsize 68

Cut for the sake of brevity - more of the same packets leaving router but nothing coming back

*Jul 11 08:35:18.247: Vi1 PPP: O pkt type 0x0021, datagramsize 42

*Jul 11 08:35:18.759: Vi1 PPP: O pkt type 0x0021, datagramsize 42

*Jul 11 08:35:20.147: Vi1 PPP: I pkt type 0xC021, datagramsize 6 link[ppp]

*Jul 11 08:35:20.199: Vi1 PPP: Outbound ip packet dropped, line protocol not up

*Jul 11 08:35:20.295: Vi1 PPP: Outbound ip packet dropped, line protocol not up

*Jul 11 08:35:20.931: Vi1 PPP: Outbound ip packet dropped, line protocol not up

*Jul 11 08:35:20.943: Vi1 PPP: Outbound ip packet dropped, line protocol not up

*Jul 11 08:35:21.171: Vi1 PPP: Outbound ip packet dropped, line protocol not up

*Jul 11 08:35:21.831: Vi1 PPP: Outbound ip packet dropped, line protocol not up

*Jul 11 08:35:22.095: Vi1 PPP: Outbound ip packet dropped, line protocol not up

*Jul 11 08:35:22.135: Vi1 PPP: No remote authentication for call-out

*Jul 11 08:35:22.135: %DIALER-6-UNBIND: Interface Vi1 unbound from profile Di0

*Jul 11 08:35:22.139: %LINEPROTO-5-UPDOWN: Line protocol on Interface Virtual-Access1, changed state to down

*Jul 11 08:35:22.139: %LINK-3-UPDOWN: Interface Virtual-Access1, changed state to down

Giuseppe Larosa · ‎07-11-2011

Hello Shane,

it would be better to see the output of debug ppp negotiation and debug ppp authentication

However, notice that after some steps the router is sending PPP LCP packets with protocol type 0x0021 and it is receving packets with protocol type 0xC021.

Clearly IPCP does not reach OPEN state so the messages like

>>*Jul 11 08:35:20.199: Vi1 PPP: Outbound ip packet dropped, line protocol not up

and before the line

*Jul 11 08:31:19.759: Vi1 LCP: Sent too many CONFNAKs. Switch to CONFREJ

I would suggest to use the above debug commands

you can follow the following link as an help in troubleshooting

http://www.cisco.com/en/US/tech/tk713/tk507/technologies_tech_note09186a00800ae945.shtml

Hope to help

Giuseppe

shanemoss · ‎07-11-2011

Thanks Giuseppe, I'll certainly follow up with the additional debugs. I've just tried with another DSL circuit that we have and it is working okay. I'll go back to the provider - is it possible that DSL synchs up okay but we might still experience issues with PPP?

Giuseppe Larosa · ‎07-11-2011

Hello Shane,

I think they have changed at least one parameter in PPPoA of the troubled link.

It is not possible to say what they have changed.

The other routers may perform different checks or they can have a looser control of PPP parameters so they are able to connect.

This is just a guess.

>>

is it possible that DSL synchs up okay but we might still experience issues with PPP?

This is possible as DSL provides OSI layer 1 and PPP frames are carried within ATM cells in AAL5 PDUs.

Hope to help

Giuseppe