["Heilmaier, Alois" <Alois.Heilmaier@xxxxxx>]

Hello,

I just captured a 802.1s BPDU and it was not decoded.
I captured on a trunk link and it was on the region boundary (maybe thats
the problem ?) on a cisco-switch.
I think there are 3 considerations applicable:

1.) ehtereal does not decode the whole packet if the MST Extension lengt ==
0 (maybe it does if it is >=1 and <=64)
2.) maybe cisco does not comply the IEEE 802.1s spec ?
3.) such a BPDU is normal on a region boundary

==> Anybody with further ideas ?

I just append the whole packet with some extractions:

Frame 1 (250 bytes on wire, 250 bytes captured)
    Arrival Time: Sep 12, 2003 16:20:25.000000000
    Time delta from previous packet: 0.000000000 seconds
    Time relative to first packet: 0.000000000 seconds
    Frame Number: 1
    Packet Length: 250 bytes
    Capture Length: 250 bytes
IEEE 802.3 Ethernet 
    Destination: 01:80:c2:00:00:00 (01:80:c2:00:00:00)
    Source: 00:50:73:69:17:fa (00:50:73:69:17:fa)
    Length: 236
Logical-Link Control
    DSAP: Spanning Tree BPDU (0x42)
    IG Bit: Individual
    SSAP: Spanning Tree BPDU (0x42)
    CR Bit: Command
    Control field: U, func = UI (0x03)
        000. 00.. = Unnumbered Information
        .... ..11 = Unnumbered frame
Spanning Tree Protocol
    Protocol Identifier: Spanning Tree Protocol (0x0000)
    Protocol Version Identifier: Multiple Spanning Tree (3)
    BPDU Type: Rapid/Multiple Spanning Tree (0x02)
    BPDU flags: 0x3c (Forwarding, Learning, Port Role: Designated)
        0... .... = Topology Change Acknowledgment: No
        .0.. .... = Agreement: No
        ..1. .... = Forwarding: Yes
        ...1 .... = Learning: Yes
        .... 11.. = Port Role: Designated (3)
        .... ..0. = Proposal: No
        .... ...0 = Topology Change: No
    Root Identifier: 32768 / 00:09:e8:99:85:80
    Root Path Cost: 0
    Bridge Identifier: 32768 / 00:09:e8:99:85:80
    Port identifier: 0x8103
    Message Age: 0
    Max Age: 20
    Hello Time: 2
    Forward Delay: 15
    Version 1 Length: 0
    MST Extension, Length: 0
[Malformed Packet: STP]

0000  01 80 c2 00 00 00 00 50 73 69 17 fa 00 ec 42 42   .......Psi....BB
0010  03 00 00 03 02 3c 80 00 00 09 e8 99 85 80 00 00   .....<..........
0020  00 00 80 00 00 09 e8 99 85 80 81 03 00 00 14 00   ................
0030  02 00 0f 00 00 00 00 c2 64 72 6e 2d 43 6f 72 65   ........drn-Core
0040  31 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   1...............
0050  00 00 00 00 00 00 00 00 00 01 8b 5c 7c 77 c3 89   ...........\|w..
0060  5f 01 0a 8f cb 23 d3 c6 0a 52 80 00 00 09 e8 99   _....#...R......
0070  85 80 00 00 00 00 14 00 02 3c 70 02 00 09 e8 99   .........<p.....
0080  85 80 00 00 00 00 70 02 00 09 e8 99 85 80 81 03   ......p.........
0090  00 00 03 3c 60 03 00 09 e8 99 85 80 00 00 00 00   ...<`...........
00a0  60 03 00 09 e8 99 85 80 81 03 00 00 06 3c 70 06   `............<p.
00b0  00 09 e8 99 85 80 00 00 00 00 70 06 00 09 e8 99   ..........p.....
00c0  85 80 81 03 00 00 07 3c 60 07 00 09 e8 99 85 80   .......<`.......
00d0  00 00 00 00 60 07 00 09 e8 99 85 80 81 03 00 00   ....`...........
00e0  08 3c 70 08 00 09 e8 99 85 80 00 00 00 00 70 08   .<p...........p.
00f0  00 09 e8 99 85 80 81 03 00 00                     ..........


Offset:		description:			value:

0x38 to 0x69	MST Config Id			64 72 6e 2d 43 6f 72 65 31
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
01 8b 5c 7c 77 c3 89 5f 01 0a 8f cb 23 d3 c6 0a 52
0x6A to 0x6D	CIST Internal Root Path Cost	80 00 00 09  (I think cisco
made an error: 80 00 00 09 e8 99 85 80 is the bridge-id)
0x6D to 0x75	CIST Bridge Identifier		e8 99 85 80 00 00 00 00
0x76			CIST Remaining Hops 		14

0x77			MSTI Flags			00
0x78 to 0x7F	MSTI Regional Root Identifier	02 3c 70 02 00 09 e8 99
0x80 to 0x83	MSTI Internal Root Path Cost	85 80 00 00
0x84 			MSTI Bridge Priority		00
0x85			MSTI Port Priority		00
0x86			MSTI Remaining Hops		70

0x87			MSTI Flags			02
0x88 to 0x8F	MSTI Regional Root Identifier	00 09 e8 99 85 80 81 03
0x90 to 0x93	MSTI Internal Root Path Cost	00 00 03 3c
0x94			MSTI Bridge Priority		60
0x95			MSTI Port Priority		03
0x96			MSTI Remaining Hops		00

0x97			MSTI Flags			09
0x98 to 0x9F	MSTI Regional Root Identifier	e8 99 85 80 00 00 00 00
0xA0 to 0xA3	MSTI Internal Root Path Cost	60 03 00 09
0xA4			MSTI Bridge Priority		e8
0xA5			MSTI Port Priority		99
0xA6			MSTI Remaining Hops		85

.......


Best Regards 
Alois