MSTP (802.1q or 802.1s) BPDU from Cisco ?

Discussion in 'Cisco' started by thomas_finne, Aug 4, 2004.

  1. thomas_finne

    thomas_finne Guest

    Hi All,
    Does any one here know what is Cisco 2950A sending out as MSTP Bpdus?

    While CIST information seems to be OK, MST Extension has another &
    unknown format.

    The version 3 length field in the Cisco BPDU is in the wrong location:
    it occupies the same location as the format selector defined in the 802.1s.

    It seems, that the 16 bytes configuration digest in the BPDU from Cisco
    does not follow the recommendation of the 802.1s. They have different
    values compared with those value shown in 802.1s Table 13-2. So Cisco
    may not use HMAC-MD5 or the signature key as specified in 802.1s 13-7
    (4), and Table 13-1.

    "CIST Internal Root Path Cost" and "CIST Bridge identifier" occupy
    wrong positions.

    "CIST Remaing hops" seems to have 2 bytes instead of 1.

    I have not discovered MST Configuarion Messages because of problems

    I was discovering CISCO bridge *C3550 Software (C3550-I5Q3L2-M),
    Version 12.1(12c)EA1* by Ethereal 0.10.5
    thomas_finne, Aug 4, 2004
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  2. thomas_finne

    Alex Rozin Guest

    Hi Thomas,
    I had (and continue to have) this problem when
    checking compatibilty our product with Cisco routers.
    I'd like to have a help in this issue too.

    Regards. Alex
    Alex Rozin, Aug 4, 2004
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  3. thomas_finne

    Thomas Finne Guest

    Hi All,
    It turned out, that my version of Cisco's switch
    is too old and these problems are well known and
    fixed in more new version. Who has at least 12.1(19)EA1d or
    whatever's latest? Can you parse/check outgoing MSTP BPDU?

    Thanks a lot, Thom
    Thomas Finne, Aug 8, 2004
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