Reference Guide

● MSTP Instances.
○ To verify the VLAN to MSTP instance mapping, use the show commands.
○ Are there “extra” MSTP instances in the Sending or Received logs? This may mean that an additional MSTP instance was
configured on one router but not the others.
The following example shows viewing an MSTP configuration.
Dell#show run spanning-tree mstp
!
protocol spanning-tree mstp
name Tahiti
revision 123
MSTI 1 VLAN 100
MSTI 2 VLAN 200,300
The following example shows viewing the debug log (a successful MSTP configuration).
Dell#debug spanning-tree mstp bpdu
MSTP debug bpdu is ON
Dell#
4w0d4h : MSTP: Sending BPDU on Te 2/21 :
ProtId: 0, Ver: 3, Bpdu Type: MSTP, Flags 0x6e
CIST Root Bridge Id: 32768:0001.e806.953e, Ext Path Cost: 0
Regional Bridge Id: 32768:0001.e806.953e, CIST Port Id: 128:470
Msg Age: 0, Max Age: 20, Hello: 2, Fwd Delay: 15, Ver1 Len: 0, Ver3 Len: 96
Name: Tahiti, Rev: 123, Int Root Path Cost: 0
Rem Hops: 20, Bridge Id: 32768:0001.e806.953e
4w0d4h : INST 1: Flags: 0x6e, Reg Root: 32768:0001.e806.953e, Int Root Cost: 0
Brg/Port Prio: 32768/128, Rem Hops: 20
INST 2: Flags: 0x6e, Reg Root: 32768:0001.e806.953e, Int Root Cost: 0
Brg/Port Prio: 32768/128, Rem Hops: 20
4w0d4h : MSTP: Received BPDU on Te 2/21 :
ProtId: 0, Ver: 3, Bpdu Type: MSTP, Flags 0x78 (Indicates MSTP routers are in the [single] region.)
CIST Root Bridge Id: 32768:0001.e806.953e, Ext Path Cost: 0
Regional Bridge Id: 32768:0001.e806.953e, CIST Port Id: 128:470
Msg Age: 0, Max Age: 20, Hello: 2, Fwd Delay: 15, Ver1 Len: 0, Ver3 Len: 96
Name: Tahiti, Rev: 123 (MSTP region name and revision), Int Root Path Cost: 0
Rem Hops: 19, Bridge Id: 32768:0001.e8d5.cbbd
4w0d4h : INST 1 (MSTP Instance): Flags: 0x78, Reg Root: 32768:0001.e806.953e, Int Root
Cost: 0
Brg/Port Prio: 32768/128, Rem Hops: 19
INST 2 (MSTP Instance): Flags: 0x78, Reg Root: 32768:0001.e806.953e, Int Root Cost: 0
Brg/Port Prio: 32768/128, Rem Hops: 19
Indicates MSTP
routers are in the
(single) region
MSTP Instance
MSTP Region name
The following example shows viewing the debug log (an unsuccessful MSTP configuration).
4w0d4h : MSTP: Received BPDU on Te 2/21 :
ProtId: 0, Ver: 3, Bpdu Type: MSTP, Flags 0x78Different Region (Indicates MSTP routers are in
different regions and are not communicating with each other.)
CIST Root Bridge Id: 32768:0001.e806.953e, Ext Path Cost: 0
Regional Bridge Id: 32768:0001.e806.953e, CIST Port Id: 128:470
Msg Age: 0, Max Age: 20, Hello: 2, Fwd Delay: 15, Ver1 Len: 0, Ver
Name: Tahiti, Rev: 123, Int Root Path Cost: 0
Rem Hops: 20, Bridge Id: 32768:0001.e8d5.cbbd
4w0d4h : INST 1: Flags: 0x70, Reg Root: 32768:0001.e8d5.cbbd, Int
Brg/Port Prio: 32768/128, Rem Hops: 20
INST 2: Flags: 0x70, Reg Root: 32768:0001.e8d5.cbbd, Int Root Cost
Brg/Port Prio: 32768/128, Rem Hops: 20
Multiple Spanning Tree Protocol (MSTP)
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