• Status: Solved
  • Priority: Medium
  • Security: Public
  • Views: 414
  • Last Modified:

2950 Switch 3500 Switch SPANNING TREE

Hi,

        I have to two switches which are connected for redundancy  both are running Spanning Tree. One switch is a 3500, and the other is a 2950. Currently the 2950 Switch is the root. The situation is that I was testing to see if the redundancy link worked, however, when I shutdown one of the ports on the 2950 which is connected to the 3500, the port which was in blocking state on the 3500, did not change its state, it just kept on blocking.

                                         Thank You
0
vreyesii
Asked:
vreyesii
  • 8
  • 8
  • 5
  • +2
2 Solutions
 
Don JohnstonInstructorCommented:
How long did you wait? It could take up to 30 seconds to converge in that scenario.

Are you sure the redundant link is functional?

-Don
0
 
vreyesiiAuthor Commented:
How can I check if the redundant link is fuctional?

               Thank You
0
 
Don JohnstonInstructorCommented:
Is it UP/UP when you do a "show interface"?

Can you see the neighboring switch with "show CDP neighbor"?

-Don
0
Technology Partners: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

 
vreyesiiAuthor Commented:
Yes I can the switch when I run show cdp neighbor also the interfaces are up/up.

                    Thank You
0
 
Don JohnstonInstructorCommented:
Then the redundant link is probably okay.

How long did you wait for the backup link to come up after shutting down the primary link?

-Don
0
 
vreyesiiAuthor Commented:
I waited about 2 mintues.

     Thank You
0
 
Don JohnstonInstructorCommented:
Can you post the configs and a "show spanning-tree" output of both switches?

-Don
0
 
mikebernhardtCommented:
Just to verify-- can you see the other switch with cdp neighbor on BOTH ports when both ports are connected, or only on one?

How are you determining whether the link is unblocked? Are you trying to forward traffic (pings or something) or looking at spanning tree commands? Are there only 2 links between them or are there more?
0
 
vreyesiiAuthor Commented:
This is the spanning-tree command results for S1

S1#show spanning-tree

Vlan 1
  Spanning tree enabled protocol ieee
  Root ID    Priority    32768
             Address     000C.2334.9874
             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     000C.2334.9874
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time 300

Interface        Port ID                     Designated                Port I
Name             Prio.Nbr      Cost Sts      Cost Bridge ID            Prio.N
---------------- -------- --------- --- --------- -------------------- ------
Fa0/2            100.2           20 FWD         0 32768 000C.2334.9874 100.2
Fa0/7            100.7          100 FWD         0 32768 000C.2334.9874 100.7

And this is the spanning-tree results for switch 2

S1#show spanning-tree

Vlan 1
  Spanning tree enabled protocol ieee
  Root ID    Priority    32768
             Address     000C.2334.9874
             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     000C.2334.9874
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time 300

Interface        Port ID                     Designated                Port I
Name             Prio.Nbr      Cost Sts      Cost Bridge ID            Prio.N
---------------- -------- --------- --- --------- -------------------- ------
Fa0/2            100.2           20 FWD         0 32768 000C.2334.9874 100.2
Fa0/7            100.7          100 FWD         0 32768 000C.2334.9874 100.7

                             Thank You
0
 
Don JohnstonInstructorCommented:
You have something else going on.

Both switches are showing as root bridges.

Can you post the configs?

-Don
0
 
mikebernhardtCommented:
It's not that they both are root, they both have the same root ID. You posted the same switch twice. They even have the same hostname...
0
 
vreyesiiAuthor Commented:
Sorry about that here is the correct configuration.

S2#show spanning-tree

Vlan 1
  Spanning tree enabled protocol ieee
  Root ID    Priority    32768
             Address     000C.2334.9874
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    32768  (priority 32768 sys-id-ext 1)
             Address     000C.2646.3311
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time 300

Interface        Port ID                     Designated                Port ID
Name             Prio.Nbr      Cost Sts      Cost Bridge ID            Prio.Nbr
---------------- -------- --------- --- --------- -------------------- --------
Fa0/4            100.4            1 FWD         0 32768 000C.2334.9874 100.4
Fa0/6            100.6            1 BLK         0 32768 000C.2334.9874 100.6


S1#show spanning-tree

Vlan 1
  Spanning tree enabled protocol ieee
  Root ID    Priority    32768
             Address     000C.2334.9874
             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     000C.2334.9874
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time 300

Interface        Port ID                     Designated                Port I
Name             Prio.Nbr      Cost Sts      Cost Bridge ID            Prio.N
---------------- -------- --------- --- --------- -------------------- ------
Fa0/2            100.2           20 FWD         0 32768 000C.2334.9874 100.2
Fa0/7            100.7          100 FWD         0 32768 000C.2334.9874 100.7

                                        Thank You
0
 
Don JohnstonInstructorCommented:
So if you go to S2 and shutdown f0/4, you're saying that f0/6 never transistions to forwarding?

0
 
mikebernhardtCommented:
OK, now please shut down the forwarding link and post the same output again. Give it about a minute before running the command. Also post the output of "show cdp neighbor."
0
 
vreyesiiAuthor Commented:
Alright, I shutdown the port f0/4 on S2 and f0/6 never changed to fowarding state.

This is the "show cdp neighbors" before I shutdown f0/4
S2#show cdp neighbors

Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
S -Switch, H - Host, i - IGMP, r - Repeater
Device ID        Local Intrfce     Holdtme    Capability  Platform  Port ID
S1                  Fas0/4         150           T S      2950      2
S1                  Fas0/6         170           T S      2950      7

And this is the "show cdp neighbors" after I shutdown f0/4 as you can see fa0/4 is out of the picture however below is what spanning-tree shows.

S2#show cdp neighbors

Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridg
S -Switch, H - Host, i - IGMP, r - Repeater
Device ID        Local Intrfce     Holdtme    Capability  Platform  Po
S1                  Fas0/6         179           T S      2950      7

S2#show spanning-tree

Vlan 1
  Spanning tree enabled protocol ieee
  Root ID    Priority    32768
             Address     000C.2415.2584
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    32769  (priority 32768 sys-id-ext 1)
             Address     000C.2692.2637
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time 300

Interface        Port ID                     Designated                Port I
Name             Prio.Nbr      Cost Sts      Cost Bridge ID            Prio.N
---------------- -------- --------- --- --------- -------------------- ------
Fa0/4            100.4            1 FWD         0 32768 000C.2415.2584 100.4
Fa0/6            100.6            1 BLK         0 32768 000C.2415.2584 100.6

                                    Thank You
0
 
mikebernhardtCommented:
Can you type "show interface status" on S2 while that port is shut down? Where did you shut it down, on S1 or S2? Have you tried disconnecting the cable or shutting down the other end? Give us a "show version" on the 3500 also. I'm starting to think "bug" on this one but let's see.
0
 
vreyesiiAuthor Commented:
Here is the show interface status, and below is a copy of the show version.

S2#show interfaces status

Port    Name               Status       Vlan       Duplex  Speed Type
Fa0/1                       notconnect    1            auto   auto 10/100BaseTX
Fa0/2                       notconnect    1            auto   auto 10/100BaseTX
Fa0/3                       notconnect    1            auto   auto 10/100BaseTX
Fa0/4                       connected     1          a-full  a-100 10/100BaseTX
Fa0/5                       notconnect    1            auto   auto 10/100BaseTX
Fa0/6                       connected     1          a-full  a-100 10/100BaseTX
Fa0/7                       notconnect    1            auto   auto 10/100BaseTX
Fa0/8                       notconnect    1            auto   auto 10/100BaseTX
Fa0/9                       notconnect    1            auto   auto 10/100BaseTX
Fa0/10                      notconnect    1            auto   auto 10/100BaseTX
Fa0/11                      notconnect    1            auto   auto 10/100BaseTX
Fa0/12                      notconnect    1            auto   auto 10/100BaseTX
Fa0/13                      notconnect    1            auto   auto 10/100BaseTX
Fa0/14                      notconnect    1            auto   auto 10/100BaseTX
S2#

S2#show version


Boson Operating Simulation Software
BOSS (tm) C3500 Software (C3500-Enterprise), Version 12.1, RELEASE SOFTWARE
Copyright (c) 1998-2003 by Boson Software, Inc.

BOSS ROM: System Bootstrap, Version 12.2, RELEASE SOFTWARE
S2 Uptime Is 0 days, 1 hour, 51 minutes
System restarted by power-on
System image file is ""flash:c3500-enterprise.12.1.boss"", booted via flash
Boson 3500 (BOSS) processor (revision 5.0)
12 FastEthernet/IEEE 802.3 interface(s)
2 Gigabit/IEEE 802.3 interface(s)

32K bytes of simulated non-volatile configuration memory.
8192K bytes of simulated System flash (Read/Write)


Configuration register is 0X2102

S2#

                                       Thank You
0
 
PennGwynCommented:
The root bridge is not allowed -- by definition -- to shutdown ports.  You need to do your test by shutting down a port from the other switch (or change priority so that the other one becomes the root).

0
 
Don JohnstonInstructorCommented:
Regardless of what you think you've done, you have not shutdown f0/4 on S2.

Either shut it down:

conf t
int f0/4
shutdown
end

Or uplug the cable.

-Don
0
 
Don JohnstonInstructorCommented:
"The root bridge is not allowed -- by definition -- to shutdown ports."

PennGwyn,

Are you saying the "shutdown" command doesn't work on a switch that is the root bridge???
0
 
lrmooreCommented:
Don, Mike,
All you network guys.. can I get an assist with this Q. Needs more attentention than I can provide in the next couple of days:

http://www.experts-exchange.com/Hardware/Routers/Q_21848834.html#16687383

Sorry about the hijack....
Thanks!
0
 
vreyesiiAuthor Commented:
Alrgiht finally I got it working I unpluged the wire and then the other port which was in blocking state came up.


                     Thanks everyone for all the help.
0
 
mikebernhardtCommented:
Penngwyn,

The root bridge by definition is not allowed to BLOCK ports within spanning tree. You can certainly administratively shut down a port!

Now, given that the "switch" is a Boson simulation, it is certainly possible that it just isn't working correctly. You can see that the port still shows connected even though you supposedly shut it down... so a physical disconnect is the only way with this software I guess.

0

Featured Post

[Webinar On Demand] Database Backup and Recovery

Does your company store data on premises, off site, in the cloud, or a combination of these? If you answered “yes”, you need a data backup recovery plan that fits each and every platform. Watch now as as Percona teaches us how to build agile data backup recovery plan.

  • 8
  • 8
  • 5
  • +2
Tackle projects and never again get stuck behind a technical roadblock.
Join Now