Strange behaviour of ISP for 0x17 LCP option! - PPP

This is a discussion on Strange behaviour of ISP for 0x17 LCP option! - PPP ; hi folks I am (unsuccessfuly) trying to connect to my ISP through a USB ISDN TA. The utilities provided by the TA also has one protocol analyzer. Here is what I see the part creating the problem: 00:38:35:76 39 bytes ...

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Thread: Strange behaviour of ISP for 0x17 LCP option!

  1. Strange behaviour of ISP for 0x17 LCP option!

    hi folks

    I am (unsuccessfuly) trying to connect to my ISP through a USB ISDN
    TA. The utilities provided by the TA also has one protocol analyzer.
    Here is what I see the part creating the problem:


    00:38:35:76 39 bytes B1 PPP REMOTE LCP Config-Req Id = 0x72
    Option(1)..Maximum-Receive-Unit:1600
    Option(5)..Magic Number:0x33B5BC55
    Option(17)..Multilink-MRRU:1600
    Option()..Type:0x17 01 91
    Option(3)..Authentication:PAP
    Option(19)..MP-EP-Discr:Class=3 08 00 03 04

    00:38:35:76 39 bytes B1 PPP LOCAL LCP Config-Rej Id = 0x72
    Option()..Type:0x17 01 91


    This process is getting repeated over and over again.
    I feel my USB TA is not understanding the option 0x17 (Link
    discriminator for BACP ...uh???).
    But why the ISP is sending the request again and again when the TA has
    rejected the option?

    The TA is working fine on other ISPs.

    Thanks in advance
    Deepak Garg

  2. Re: Strange behaviour of ISP for 0x17 LCP option!

    deepak_garg@rediffmail.com (deepak) writes:
    > This process is getting repeated over and over again.
    > I feel my USB TA is not understanding the option 0x17 (Link
    > discriminator for BACP ...uh???).


    Because it's mangled. 0x17 01 91 isn't a possible legal LCP option.
    The length octet (01) isn't at least the minimum legal value (02).

    Sounds to me like a bug in the equipment this ISP is using.

    --
    James Carlson, IP Systems Group
    Sun Microsystems / 1 Network Drive 71.234W Vox +1 781 442 2084
    MS UBUR02-212 / Burlington MA 01803-2757 42.497N Fax +1 781 442 1677

  3. Re: Strange behaviour of ISP for 0x17 LCP option!

    deepak_garg@rediffmail.com (deepak) writes:
    > 00:38:35:76 39 bytes B1 PPP REMOTE LCP Config-Req Id = 0x72
    > Option(1)..Maximum-Receive-Unit:1600
    > Option(5)..Magic Number:0x33B5BC55
    > Option(17)..Multilink-MRRU:1600
    > Option()..Type:0x17 01 91
    > Option(3)..Authentication:PAP
    > Option(19)..MP-EP-Discr:Class=3 08 00 03 04
    >
    > 00:38:35:76 39 bytes B1 PPP LOCAL LCP Config-Rej Id = 0x72
    > Option()..Type:0x17 01 91


    Ah, wait. I think I misinterpreted that strange debug output. What
    the TA really received was (hex) 17 02 01 91 -- option 0x17 with data
    01 91. That's legal. My mistake.

    > This process is getting repeated over and over again.
    > I feel my USB TA is not understanding the option 0x17 (Link
    > discriminator for BACP ...uh???).


    This still points to a likely ISP bug. Implementations are _required_
    to accept and respond to Configure-Reject messages.

    --
    James Carlson, IP Systems Group
    Sun Microsystems / 1 Network Drive 71.234W Vox +1 781 442 2084
    MS UBUR02-212 / Burlington MA 01803-2757 42.497N Fax +1 781 442 1677

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