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ISDN LCP Failure Mystery

Unanswered Question
Oct 6th, 2006
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I have an ISDN line that I am able to complete a good call, but am unable to complete good LCP negotiations. I checked the usual suspects, such as matching encap and bandwidth statements on both sides. What I am seeing in debug (shown below) is that both sides are sending an identification request (confreq), but neither side appears to be sending a CONFACK, therby completing TEI negotiations. I am not incrementing any errors and telco is testing ok. Also provisioning has been checked out as well. Anybody got any ideas as to a possible root cause here?

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BRI0:1 is up, line protocol is down

Hardware is PQUICC BRI with U interface (Infenion)

MTU 1500 bytes, BW 64 Kbit, DLY 20000 usec,

reliability 255/255, txload 1/255, rxload 1/255

Encapsulation PPP, LCP REQsent, multilink Closed

Closed: BACP, loopback not set idle 00:01:55

Last input never, output 00:00:00, output hang never

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HUB SID

Oct 5 15:47:33.233 cdt: %ISDN-6-CONNECT: Interface Serial2/0:1 is now connected to 6308201780

Oct 5 15:47:33.233 cdt: Se2/0:1 LCP: TIMEout: State REQsent

Oct 5 15:47:33.233 cdt: Se2/0:1 LCP: O CONFREQ [REQsent] id 160 len 30

Oct 5 15:47:33.233 cdt: Se2/0:1 LCP: AuthProto CHAP (0x0305C22305)

Oct 5 15:47:33.233 cdt: Se2/0:1 LCP: MagicNumber 0xA3853BD5 (0x0506A3853BD5)

Oct 5 15:47:33.233 cdt: Se2/0:1 LCP: MRRU 1524 (0x110405F4)

Oct 5 15:47:33.233 cdt: Se2/0:1 LCP: EndpointDisc 1 aascisdn (0x130B01616173636973646E)

Oct 5 15:47:35.234 cdt: Se2/0:1 LCP: TIMEout: State REQsent

Oct 5 15:47:35.234 cdt: Se2/0:1 LCP: O CONFREQ [REQsent] id 161 len 30

Oct 5 15:47:35.234 cdt: Se2/0:1 LCP: AuthProto CHAP (0x0305C22305)

Oct 5 15:47:35.234 cdt: Se2/0:1 LCP: MagicNumber 0xA3853BD5 (0x0506A3853BD5)

Oct 5 15:47:35.234 cdt: Se2/0:1 LCP: MRRU 1524 (0x110405F4)

Oct 5 15:47:35.234 cdt: Se2/0:1 LCP: EndpointDisc 1 aascisdn (0x130B01616173636973646E)

Oct 5 15:47:37.234 cdt: Se2/0:1 LCP: TIMEout: State REQsent

Oct 5 15:47:37.234 cdt: Se2/0:1 LCP: O CONFREQ [REQsent] id 162 len 30

Oct 5 15:47:37.234 cdt: Se2/0:1 LCP: AuthProto CHAP (0x0305C22305)

Oct 5 15:47:37.234 cdt: Se2/0:1 LCP: MagicNumber 0xA3853BD5 (0x0506A3853BD5)

Oct 5 15:47:37.234 cdt: Se2/0:1 LCP: MRRU 1524 (0x110405F4)

Oct 5 15:47:37.234 cdt: Se2/0:1 LCP: EndpointDisc 1 aascisdn (0x130B01616173636973646E)


REMOTE SIDE

Oct 5 15:41:55.598 cdt: %LINK-3-UPDOWN: Interface BRI0:1, changed state to up

Oct 5 15:41:55.630 cdt: BR0:1 PPP: Using dialer call direction

Oct 5 15:41:55.630 cdt: BR0:1 PPP: Treating connection as a callout

Oct 5 15:41:55.630 cdt: BR0:1 PPP: Phase is ESTABLISHING, Active Open

Oct 5 15:41:55.630 cdt: BR0:1 LCP: O CONFREQ [Closed] id 15 len 15

Oct 5 15:41:55.630 cdt: BR0:1 LCP: AuthProto CHAP (0x0305C22305)

Oct 5 15:41:55.634 cdt: BR0:1 LCP: MagicNumber 0xE311DB4A (0x0506E311DB4A).

Oct 5 15:41:57.598 cdt: BR0:1 LCP: TIMEout: State REQsent

Oct 5 15:41:57.598 cdt: BR0:1 LCP: O CONFREQ [REQsent] id 16 len 15

Oct 5 15:41:57.598 cdt: BR0:1 LCP: AuthProto CHAP (0x0305C22305)

Oct 5 15:41:57.598 cdt: BR0:1 LCP: MagicNumber 0xE311DB4A (0x0506E311DB4A).

Oct 5 15:41:59.614 cdt: BR0:1 LCP: TIMEout: State REQsent

Oct 5 15:41:59.614 cdt: BR0:1 LCP: O CONFREQ [REQsent] id 17 len 15

Oct 5 15:41:59.614 cdt: BR0:1 LCP: AuthProto CHAP (0x0305C22305)

Oct 5 15:41:59.614 cdt: BR0:1 LCP: MagicNumber 0xE311DB4A (0x0506E311DB4A).

Oct 5 15:42:01.602 cdt: %ISDN-6-CONNECT: Interface BRI0:1 is now connected to 17733997800

Oct 5 15:42:01.630 cdt: BR0:1 LCP: TIMEout: State REQsent

Oct 5 15:42:01.630 cdt: BR0:1 LCP: O CONFREQ [REQsent] id 18 len 15

Oct 5 15:42:01.630 cdt: BR0:1 LCP: AuthProto CHAP (0x0305C22305)

Oct 5 15:42:01.630 cdt: BR0:1 LCP: MagicNumber 0xE311DB4A (0x0506E311DB4A).

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stevennowell Fri, 10/06/2006 - 13:29
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should have typed "completing lcp negotiations" above. (correcting myself)

Perdue Farms Sun, 03/25/2007 - 08:55
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I am having the same problem with analog modem connected through aux port. line is clean, call completes, but the remote router is sending a lot of REQ but no ACK.


Happens to about 10% of our remote sites, they are unable to dial in for hours, when then later it works mysteriously. Its for 2800/3600/1750 routers dialing into AS5300.


Anyone have any ideas? The modem, cable, lines have all been switched out, and like I said, the call connects fine, but PPP negotiation times out due to no ACKS received.

paolo bevilacqua Sun, 03/25/2007 - 12:19
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IOS used on these ? Any chances you are running in PPP / ISDN bugs ?

paolo bevilacqua Sun, 03/25/2007 - 13:33
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Would upgrade to the latest maintenance of appropriate version and check again.



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