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Community Member

Differences in Show Spanning-Tree Output

This is the output of a "show spanning-tree on a Catalyst 3524 using IOS 12.0(5)WC16

Spanning tree 1 is executing the IEEE compatible Spanning Tree protocol
  Bridge Identifier has priority 32768, address 000c.309e.af80
  Configured hello time 2, max age 20, forward delay 15
  We are the root of the spanning tree
  Topology change flag not set, detected flag not set, changes 3
  Times:  hold 1, topology change 35, notification 2
          hello 2, max age 20, forward delay 15
  Timers: hello 1, topology change 0, notification 0

Interface Fa0/1 (port 13) in Spanning tree 1 is FORWARDING
   Port path cost 19, Port priority 128
   Designated root has priority 32768, address 000c.309e.af80
   Designated bridge has priority 32768, address 000c.309e.af80
   Designated port is 13, path cost 0
   Timers: message age 0, forward delay 0, hold 0
   BPDU: sent 3127, received 200

Interface Fa0/3 (port 15) in Spanning tree 1 is FORWARDING
   Port path cost 19, Port priority 128
   Designated root has priority 32768, address 000c.309e.af80
   Designated bridge has priority 32768, address 000c.309e.af80
   Designated port is 15, path cost 0
   Timers: message age 0, forward delay 0, hold 0
   BPDU: sent 3032, received 95

And this is the output of a "show spanning-tree" on a 3560 using IOS 12.2(25r)

VLAN0100
  Spanning tree enabled protocol ieee
  Root ID    Priority    32768
             Address     000c.309e.af81
             Cost        19
             Port        3 (FastEthernet0/1)
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    32868  (priority 32768 sys-id-ext 100)
             Address     0018.738d.9300
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time 300

Interface        Role Sts Cost      Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Fa0/1            Root FWD 19        128.3    P2p
Fa0/3            Desg FWD 19        128.5    P2p

The output of show spanning-tree I am familiar with, and that I have seen in my BCMSN book is the output of the second switch (the 3560).

Was show spanning-tree much different in earlier IOS ver.?

Also, in the first output example, what does the port (xx) mean? Where are the port states per interface the way they are listed in the more recent IOS show spanning-tree output.

How do I read the output? Any documents?]

Thanks.

5 REPLIES
Hall of Fame Super Blue

Re: Differences in Show Spanning-Tree Output

nelson.garcia wrote:

This is the output of a "show spanning-tree on a Catalyst 3524 using IOS 12.0(5)WC16

Spanning tree 1 is executing the IEEE compatible Spanning Tree protocol
  Bridge Identifier has priority 32768, address 000c.309e.af80
  Configured hello time 2, max age 20, forward delay 15
  We are the root of the spanning tree
  Topology change flag not set, detected flag not set, changes 3
  Times:  hold 1, topology change 35, notification 2
          hello 2, max age 20, forward delay 15
  Timers: hello 1, topology change 0, notification 0

Interface Fa0/1 (port 13) in Spanning tree 1 is FORWARDING
   Port path cost 19, Port priority 128
   Designated root has priority 32768, address 000c.309e.af80
   Designated bridge has priority 32768, address 000c.309e.af80
   Designated port is 13, path cost 0
   Timers: message age 0, forward delay 0, hold 0
   BPDU: sent 3127, received 200

Interface Fa0/3 (port 15) in Spanning tree 1 is FORWARDING
   Port path cost 19, Port priority 128
   Designated root has priority 32768, address 000c.309e.af80
   Designated bridge has priority 32768, address 000c.309e.af80
   Designated port is 15, path cost 0
   Timers: message age 0, forward delay 0, hold 0
   BPDU: sent 3032, received 95

And this is the output of a "show spanning-tree" on a 3560 using IOS 12.2(25r)

VLAN0100
  Spanning tree enabled protocol ieee
  Root ID    Priority    32768
             Address     000c.309e.af81
             Cost        19
             Port        3 (FastEthernet0/1)
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    32868  (priority 32768 sys-id-ext 100)
             Address     0018.738d.9300
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time 300

Interface        Role Sts Cost      Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Fa0/1            Root FWD 19        128.3    P2p
Fa0/3            Desg FWD 19        128.5    P2p

The output of show spanning-tree I am familiar with, and that I have seen in my BCMSN book is the output of the second switch (the 3560).

Was show spanning-tree much different in earlier IOS ver.?

Also, in the first output example, what does the port (xx) mean? Where are the port states per interface the way they are listed in the more recent IOS show spanning-tree output.

How do I read the output? Any documents?]

Thanks.

Nelson

Was there something in particular you were looking for from the first output. If you look carefully at the output from the 3524 switch it actually contains pretty much the same information as the 3560 just in a different format.

Jon

Community Member

Re: Differences in Show Spanning-Tree Output

Spanning  tree 1 is executing the IEEE compatible Spanning Tree protocol
   Bridge Identifier has priority 32768, address 000c.309e.af80
   Configured hello time 2, max age 20, forward delay 15
  We are the  root of the spanning tree
  Topology change flag not set, detected  flag not set, changes 3
  Times:  hold 1, topology change 35,  notification 2
          hello 2, max age 20, forward delay 15
   Timers: hello 1, topology change 0, notification 0

Interface  Fa0/1 (port 13) in Spanning tree 1 is FORWARDING
   Port path cost  19, Port priority 128
   Designated root has priority 32768, address  000c.309e.af80
   Designated bridge has priority 32768, address  000c.309e.af80
   Designated port is 13, path cost 0
   Timers:  message age 0, forward delay 0, hold 0
   BPDU: sent 3127, received  200

Interface  Fa0/3 (port 15) in Spanning tree 1 is FORWARDING
   Port path cost  19, Port priority 128
   Designated root has priority 32768, address  000c.309e.af80
   Designated bridge has priority 32768, address  000c.309e.af80
   Designated port is 15, path cost 0
   Timers:  message age 0, forward delay 0, hold 0
   BPDU: sent 3032, received  95

Asfar as knowing what the root port is. Is this bridge the root bridge because both trunk interfaces are in a forwarding state, and, as I understand, all ports on the root bridge forward traffic?

In this line here "Interface  Fa0/3 (port 15) in Spanning tree 1 is FORWARDING" what does "(port15)" mean?

Hall of Fame Super Blue

Re: Differences in Show Spanning-Tree Output

nelson.garcia wrote:

Spanning  tree 1 is executing the IEEE compatible Spanning Tree protocol
   Bridge Identifier has priority 32768, address 000c.309e.af80
   Configured hello time 2, max age 20, forward delay 15
  We are the  root of the spanning tree
  Topology change flag not set, detected  flag not set, changes 3
  Times:  hold 1, topology change 35,  notification 2
          hello 2, max age 20, forward delay 15
   Timers: hello 1, topology change 0, notification 0

Interface  Fa0/1 (port 13) in Spanning tree 1 is FORWARDING
   Port path cost  19, Port priority 128
   Designated root has priority 32768, address  000c.309e.af80
   Designated bridge has priority 32768, address  000c.309e.af80
   Designated port is 13, path cost 0
   Timers:  message age 0, forward delay 0, hold 0
   BPDU: sent 3127, received  200

Interface  Fa0/3 (port 15) in Spanning tree 1 is FORWARDING
   Port path cost  19, Port priority 128
   Designated root has priority 32768, address  000c.309e.af80
   Designated bridge has priority 32768, address  000c.309e.af80
   Designated port is 15, path cost 0
   Timers:  message age 0, forward delay 0, hold 0
   BPDU: sent 3032, received  95

Asfar as knowing what the root port is. Is this bridge the root bridge because both trunk interfaces are in a forwarding state, and, as I understand, all ports on the root bridge forward traffic?

In this line here "Interface  Fa0/3 (port 15) in Spanning tree 1 is FORWARDING" what does "(port15)" mean?

Nelson

From the output above -

We are the  root of the spanning tree

int fa0/3 (port 15) - as far as i know this is just an internal STP reference.

Jon

Bronze

Re: Differences in Show Spanning-Tree Output

I beleive the different outputs are tied more to hardware platform than IOS version.   I say this because I have an 880 router running IOS 12.4T, and my output is in the same format as your 3500XL switch.  My guess is it might have something to with RSTP (802.1w) and MSTP (802.1s) support.   The 880 is a brand new model, but only runs PVST.   This is just a guess...you'd probably have to ask someone at Cisco to know for sure.

To view STP details of a port, just use "show spanning-tree interface detail", or "show spanning-tree vlan interface detail" for a specific VLAN.  For example:

cat2950#show spanning-tree vlan 1 interface fa0/1 det
Port 1 (FastEthernet0/1) of VLAN0001 is root forwarding
   Port path cost 19, Port priority 128, Port Identifier 128.1.
   Designated root has priority 0, address 0023.eb56.f5c2
   Designated bridge has priority 0, address 0023.eb56.f5c2
   Designated port id is 128.1, designated path cost 0
   Timers: message age 16, forward delay 0, hold 0
   Number of transitions to forwarding state: 1
   Link type is point-to-point by default, Peer is STP
   Loop guard is enabled by default on the port
   BPDU: sent 6, received 66

Community Member

Re: Differences in Show Spanning-Tree Output

Thank you, gentlemen, for your quick and informative responses.

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