14.
Multiple Spanning Tree Protocol (MSTP)
MN700004 Rev 01
162
MSTI configuration Identifier
(Key, Revision, Name) 50
Bytes.
00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00
00 00 00 00 64 b1 f4 bb 1f 3c
6d 4d a3 00 94 c1 11 b7 c0 92
The first byte of the
configuration is called selector,
and is omitted (or over-ridden
by the version 3 length field)
CIST Regional Root Identifier
60 00 00 07 eb d5 a2 00
The fields order is flipped.
CIST Internal Root Path Cost
00 00 00 00
CIST Remaining hops – 2
bytes instead of 1.
14 00
Extra byte - Cisco BPDU with no
MSTIs ends here and contains
the extra byte.
MSTI1
MSTID
Flags
MSTI Regional Root Identifier
01
69
60 01 00 07 eb d5 a2 00
The whole M-Record structure is
different. In the 802.1s there is
no MSTID field. The priority of
the sending bridge and the port
priority are sent without bridge
ID and port ID of the sending
bridge.
MSTI Internal root path cost
MSTI Transmitting Bridge
Idnetifier
MSTI Port Identifier
MSTI Remaining hops
00 00 00 00
60 01 00 07 eb d5 a2 00
80 01
14 00
NOTE
If the Cisco BPDUs are parsed as specified in IEEE 802.1s standard, some offsets and shifts
may cause wrong values for the M-records and for the matching fields that are located after
the version 3 length - CIST Internal root path cost, CIST Bridge identifier, CIST remaining
hops.
Displaying MSTP Configuration
Table 14-9 lists the MSTP Display commands.
Table 14-9 MSTP Display Commands
C o m m a n d D e s c r i p t i o n
show pending
Displays the temporary configuration.
show
Displays the MSTP configuration.
show mstp configuration
Displays the MSTP configuration in the current region.
show mstp
Displays the whole MSTP configuration.
show mstp instance
Displays the configured instances.