Spanning Tree does not work on Cisco 3550 Switch

I bought a stack of used routers and switches recently, and I've been studying for my CCNA exam. The problem is when I got to lab 5.5.2 in the switching lab book my 3550 switch could not use spanning tree anymore. 5.5.1 worked no problem, but for some reason my switch can not use or see any spanning tree. It just keeps saying "No instance of spanning tree." I googled the problem already, and my ports and VLANs and everything is on. Can someone help please?

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Comments

MAC_Addy

What have you done to configure STP on your switches? Also, if you'd post the running-configs, that would help a lot.

TheNewITGuy

spanning-tree may not show a running instance because there is no stp topology setup. (ie: no need for spanning tree)

Donnelly82

heres my 3350 spanning-tree...

Switch_3550#show spanning-tree

VLAN0001
Spanning tree enabled protocol rstp
Root ID Priority 32769
Address 0009.e83f.ef00
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32769 (priority 32768 sys-id-ext 1)
Address 0009.e83f.ef00
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300 sec

Interface Role Sts Cost Prio.Nbr Type

---- ---

Fa0/1 Desg FWD 19 128.1 P2p Edge
Fa0/2 Desg FWD 19 128.2 P2p Edge
Fa0/12 Desg FWD 19 128.12 P2p Edge
Fa0/13 Desg FWD 19 128.13 P2p
Fa0/24 Desg FWD 19 128.24 P2p

Running config
........
spanning-tree mode rapid-pvst
spanning-tree etherchannel guard misconfig
spanning-tree extend system-id
!
vlan internal allocation policy ascending
!
ip tcp synwait-time 5
ip ssh version 2

interface FastEthernet0/13
switchport trunk encapsulation dot1q
switchport mode trunk
!

interface FastEthernet0/24
switchport trunk encapsulation dot1q
switchport mode trunk

hopefully some of this info will help??
all the best

xXErebuS

Is there a link between the switch on Fa0/13 and the switch on Fa0/24?

Architect192

How are your switches wired together? What is the configuration of the other switch?

Phantom914

This is my wiring and here is the Running Config:
S3#sh run
Building configuration...

Current configuration : 2543 bytes
!
version 12.1
no service pad
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname S3
!
!
ip subnet-zero
!
no ip domain-lookup
ip ssh time-out 120
ip ssh authentication-retries 3
!
spanning-tree mode pvst
spanning-tree extend system-id
!
!
!
!
!
interface FastEthernet0/1
switchport trunk native vlan 99
switchport mode dynamic desirable
shutdown
!
interface FastEthernet0/2
switchport trunk native vlan 99
switchport mode dynamic desirable
shutdown
!
interface FastEthernet0/3
switchport trunk native vlan 99
switchport mode dynamic desirable
shutdown
!
interface FastEthernet0/4
switchport trunk native vlan 99
switchport mode dynamic desirable
shutdown
!
interface FastEthernet0/5
switchport mode dynamic desirable
shutdown
!
interface FastEthernet0/6
switchport mode dynamic desirable
shutdown
!
interface FastEthernet0/7
switchport mode dynamic desirable
shutdown
!
interface FastEthernet0/8
switchport mode dynamic desirable
shutdown
!
interface FastEthernet0/9
switchport mode dynamic desirable
shutdown
!
interface FastEthernet0/10
switchport mode dynamic desirable
shutdown
!
interface FastEthernet0/11
switchport mode dynamic desirable
shutdown
!
interface FastEthernet0/12
switchport mode dynamic desirable
shutdown
!
interface FastEthernet0/13
switchport mode dynamic desirable
shutdown
!
interface FastEthernet0/14
switchport mode dynamic desirable
shutdown
!
interface FastEthernet0/15
switchport mode dynamic desirable
shutdown
!
interface FastEthernet0/16
switchport mode dynamic desirable
shutdown
!
interface FastEthernet0/17
switchport mode dynamic desirable
shutdown
!
interface FastEthernet0/18
switchport mode dynamic desirable
shutdown
!
interface FastEthernet0/19
switchport mode dynamic desirable
shutdown
!
interface FastEthernet0/20
switchport mode dynamic desirable
shutdown
!
interface FastEthernet0/21
switchport mode dynamic desirable
shutdown
!
interface FastEthernet0/22
switchport mode dynamic desirable
shutdown
!
interface FastEthernet0/23
switchport mode dynamic desirable
shutdown
!
interface FastEthernet0/24
switchport mode dynamic desirable
shutdown
!
interface GigabitEthernet0/1
switchport mode dynamic desirable
!
interface GigabitEthernet0/2
switchport mode dynamic desirable
!
interface Vlan1
no ip address
shutdown
!
interface Vlan99
ip address 172.17.99.13 255.255.255.0
!
ip classless
ip http server
!
!
line con 0
logging synchronous
line vty 0 4
login
line vty 5 15
login
!
!
end

What happens when I try to show spanning tree after enabling it.

S3#sh spanning-tree

No spanning tree instance exists.

S3#conf t
Enter configuration commands, one per line. End with CNTL/Z.
S3(config)#spanning-tree vlan 99
S3(config)#^Z
S3#
00:09:23: %SYS-5-CONFIG_I: Configured from console by console
S3#sh spanning-tree

No spanning tree instance exists.

S3#conf t
Enter configuration commands, one per line. End with CNTL/Z.
S3(config)#spanning-tree vlan 10
S3(config)#^Z
00:12:57: %SYS-5-CONFIG_I: Configured from console by console
S3#show spanning-t

No spanning tree instance exists

VLAN Brief:
S3#show vlan br

VLAN Name Status Ports
----

1 default active Fa0/1, Fa0/2, Fa0/3, Fa0/4
Fa0/5, Fa0/6, Fa0/7, Fa0/8
Fa0/9, Fa0/10, Fa0/11, Fa0/12
Fa0/13, Fa0/14, Fa0/15, Fa0/16
Fa0/17, Fa0/18, Fa0/19, Fa0/20
Fa0/21, Fa0/22, Fa0/23, Fa0/24
Gi0/1, Gi0/2
10 faculty-staff active
20 students active
30 guest active
99 management active
1002 fddi-default act/unsup
1003 token-ring-default act/unsup
1004 fddinet-default act/unsup
1005 trnet-default act/unsup

Switch topology.jpg

Architect192

What about S1 and S2? Spanning tree will come up when there is a loop created. Are your interfaces Fa0/1-0/4 up? You're showing us the VLAN status but the interfaces must be live and communicating.

EDIT: I just rechecked your configuration: Ports 1-4 are all shutdown...

networker050184

Architect192 wrote: »

Spanning tree will come up when there is a loop created.

That is not ture. You do not need a loop for STP to start. Just a port in the up condition assigned to an existing VLAN.

thinguy

What do the other switches say about STP status?
Do all of them have "spanning-tree extend system-id" set? Try removing that.

Architect192

networker050184 wrote: »

That is not ture. You do not need a loop for STP to start. Just a port in the up condition assigned to an existing VLAN.

True, my mistake. Possibility of a loop, not an actual loop. (if all ports are shutdown like in the OP's config, this condition doesnt exist so STP doesn't come up).

Phantom914

I actually posted the wrong config, but it wasn't fully wrong. I guess I didn't copy the run that day. I'll post a lot more info after work.

networker050184

Post the output of show ip interface brief.

Phantom914

Ok, so I don't know if you'll all be mad, but it worked somehow.

S3(config-if-range)#no shut
S3(config-if-range)#
00:01:23: %LINK-3-UPDOWN: Interface FastEthernet0/1, changed state to up
00:01:23: %LINK-3-UPDOWN: Interface FastEthernet0/2, changed state to up
00:01:23: %LINK-3-UPDOWN: Interface FastEthernet0/3, changed state to up
00:01:23: %LINK-3-UPDOWN: Interface FastEthernet0/4, changed state to up
S3(config-if-range)#
00:01:27: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, chang
ed state to up
00:01:27: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/2, chang
ed state to up
00:01:27: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/3, chang
ed state to up
00:01:27: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/4, chang
ed state to up
S3(config-if-range)#^Z
S3#
00:01:30: %SYS-5-CONFIG_I: Configured from console by console
S3#conf t
Enter configuration commands, one per line. End with CNTL/Z.
S3(config)#spanning-tree vlan 99
S3(config)#^Z
00:01:51: %SYS-5-CONFIG_I: Configured from console by console
S3#sh spanning-t

VLAN0001
Spanning tree enabled protocol ieee
Root ID Priority 32769
Address 0008.2058.0fc0
Cost 19
Port 3 (FastEthernet0/3)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32769 (priority 32768 sys-id-ext 1)
Address 0011.20c2.b600
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 15

Interface Role Sts Cost
00:01:57: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan99, changed state
to up Prio.Nbr Type

---- ---

Fa0/1 Altn BLK 19 128.1 P2p
Fa0/2 Altn BLK 19 128.2 P2p
Fa0/3 Root FWD 19 128.3 P2p
Fa0/4 Altn BLK 19 128.4 P2p

VLAN0010
Spanning tree enabled protocol ieee
Root ID Priority 32778
Address 0008.2058.0fc0
Cost 19
Port 3 (FastEthernet0/3)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32778 (priority 32768 sys-id-ext 10)
Address 0011.20c2.b600
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 15

Interface Role Sts Cost Prio.Nbr Type

---- ---

Fa0/1 Altn BLK 19 128.1 P2p
Fa0/2 Altn BLK 19 128.2 P2p
Fa0/3 Root FWD 19 128.3 P2p
Fa0/4 Altn BLK 19 128.4 P2p

VLAN0020
Spanning tree enabled protocol ieee
Root ID Priority 32788
Address 0008.2058.0fc0
Cost 19
Port 3 (FastEthernet0/3)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32788 (priority 32768 sys-id-ext 20)
Address 0011.20c2.b600
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 15

Interface Role Sts Cost Prio.Nbr Type

---- ---

Fa0/1 Altn BLK 19 128.1 P2p
Fa0/2 Altn BLK 19 128.2 P2p
Fa0/3 Root FWD 19 128.3 P2p
Fa0/4 Altn BLK 19 128.4 P2p

VLAN0030
Spanning tree enabled protocol ieee
Root ID Priority 32798
Address 0008.2058.0fc0
Cost 19
Port 3 (FastEthernet0/3)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32798 (priority 32768 sys-id-ext 30)
Address 0011.20c2.b600
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 15

Interface Role Sts Cost Prio.Nbr Type

---- ---

Fa0/1 Altn BLK 19 128.1 P2p
Fa0/2 Altn BLK 19 128.2 P2p
Fa0/3 Root FWD 19 128.3 P2p
Fa0/4 Altn BLK 19 128.4 P2p

VLAN0099
Spanning tree enabled protocol ieee
Root ID Priority 32867
Address 0008.2058.0fc0
Cost 19
Port 3 (FastEthernet0/3)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32867 (priority 32768 sys-id-ext 99)
Address 0011.20c2.b600
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 15

Interface Role Sts Cost Prio.Nbr Type

---- ---

Fa0/1 Altn BLK 19 128.1 P2p
Fa0/2 Altn BLK 19 128.2 P2p
Fa0/3 Root FWD 19 128.3 P2p
Fa0/4 Altn BLK 19 128.4 P2p

S3#conf t
Enter configuration commands, one per line. End with CNTL/Z.
S3(config)#^Z
S3#show
00:02:28: %SYS-5-CONFIG_I: Configured from console by console
S3#show vlan brief

VLAN Name Status Ports
----

1 default active Fa0/5, Fa0/6, Fa0/7, Fa0/8
Fa0/9, Fa0/10, Fa0/11, Fa0/12
Fa0/13, Fa0/14, Fa0/15, Fa0/16
Fa0/17, Fa0/18, Fa0/19, Fa0/20
Fa0/21, Fa0/22, Fa0/23, Fa0/24
Gi0/1, Gi0/2
10 faculty-staff active
20 students active
30 guest active
99 management active
1002 fddi-default act/unsup
1003 token-ring-default act/unsup
1004 fddinet-default act/unsup
1005 trnet-default act/unsup
S3#sh ip int brief
Interface IP-Address OK? Method Status Prot
ocol
Vlan1 unassigned YES NVRAM administratively down down

Vlan99 172.17.99.13 YES NVRAM up up

FastEthernet0/1 unassigned YES unset up up

FastEthernet0/2 unassigned YES unset up up

FastEthernet0/3 unassigned YES unset up up

FastEthernet0/4 unassigned YES unset up up

FastEthernet0/5 unassigned YES unset administratively down down

FastEthernet0/6 unassigned YES unset administratively down down

FastEthernet0/7 unassigned YES unset administratively down down

FastEthernet0/8 unassigned YES unset administratively down down

FastEthernet0/9 unassigned YES unset administratively down down

FastEthernet0/10 unassigned YES unset administratively down down

FastEthernet0/11 unassigned YES unset administratively down down

FastEthernet0/12 unassigned YES unset administratively down down

FastEthernet0/13 unassigned YES unset administratively down down

FastEthernet0/14 unassigned YES unset administratively down down

FastEthernet0/15 unassigned YES unset administratively down down

FastEthernet0/16 unassigned YES unset administratively down down

FastEthernet0/17 unassigned YES unset administratively down down

FastEthernet0/18 unassigned YES unset administratively down down

FastEthernet0/19 unassigned YES unset administratively down down

FastEthernet0/20 unassigned YES unset administratively down down

FastEthernet0/21 unassigned YES unset administratively down down

FastEthernet0/22 unassigned YES unset administratively down down

FastEthernet0/23 unassigned YES unset administratively down down

FastEthernet0/24 unassigned YES unset administratively down down

GigabitEthernet0/1 unassigned YES unset down down

GigabitEthernet0/2 unassigned YES unset down down

And yes it says Fa0/1 - 4 are up now, which I definitely did fix last time I tried to make spanning tree work. I don't know, maybe the auto trunking isn't working correctly on this switch?

iamme4eva

+1 for what networker said. Proof that STP works without a loop is to take a switch, clear the configs, plug just one host into it. It will take 30 secs before the light goes green. That's the spanning-tree instance for VLAN 1 doing it's job.

Phantom, there is no need to enable spanning tree per VLAN...I see you keep doing this:

S3(config)#spanning-tree vlan 99
S3(config)#^Z

When you run PVST, a spanning tree instance is automagically created for every VLAN on the switch which has an active port in it.

Hondabuff

I would change Switch(config)#no spanning-tree portfast default or do a erase startup-config and reload. Looks like you have rapid spanning tree enabled globally on the switch.

networker050184

Phantom914 wrote: »

Ok, so I don't know if you'll all be mad, but it worked somehow.

The somehow is this.

Phantom914 wrote: »

S3(config-if-range)#no shut
S3(config-if-range)#
00:01:23: %LINK-3-UPDOWN: Interface FastEthernet0/1, changed state to up
00:01:23: %LINK-3-UPDOWN: Interface FastEthernet0/2, changed state to up
00:01:23: %LINK-3-UPDOWN: Interface FastEthernet0/3, changed state to up
00:01:23: %LINK-3-UPDOWN: Interface FastEthernet0/4, changed state to up
S3(config-if-range)#
00:01:27: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, chang
ed state to up
00:01:27: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/2, chang
ed state to up
00:01:27: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/3, chang
ed state to up
00:01:27: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/4, chang
ed state to up

You don't need this.

Phantom914 wrote: »

S3(config-if-range)#^Z
S3#
00:01:30: %SYS-5-CONFIG_I: Configured from console by console
S3#conf t
Enter configuration commands, one per line. End with CNTL/Z.
S3(config)#spanning-tree vlan 99
S3(config)#^Z
00:01:51: %SYS-5-CONFIG_I: Configured from console by console

All you need is a port in the 'up' state and STP kicks in by default.

Phantom914

iamme4eva wrote: »

+1 for what networker said. Proof that STP works without a loop is to take a switch, clear the configs, plug just one host into it. It will take 30 secs before the light goes green. That's the spanning-tree instance for VLAN 1 doing it's job.

Phantom, there is no need to enable spanning tree per VLAN...I see you keep doing this:

When you run PVST, a spanning tree instance is automagically created for every VLAN on the switch which has an active port in it.

I was only doing that because there was no spanning tree working before. The auto trunk/switchport thing on it wasn't working correctly, I think because I had one switch as a server for VTP and 2 as clients. my other switch that I need to set the trunk got the info, but this 3550 wasn't getting it even with the trunk ports on.

networker050184

That is because the trunk ports were not up. As soon as they come up the STP instance kicks in.