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RSTP troubleshooting

Hi,

I've got some problems with a complex network using rstp.

As a student I've got to find a solution to make a fully redudant topology:   

CoreSwitch1 :------------------------------:CoreSwitch2

So the 2 core, as it can be seen above, are connecte together and the core "switch1" is the vtp root in the topology.

And it's critical for the network that an "old" catalyst 6513 is the bridge of the entire network, so we have decided to put a stack of 2 catalyst 3750 above the 2 core to ensure redudancy and security.

Here is the new topology:

                  SwitchStack3750

                 /                          \

                /                            \

CoreSwitch1 :----------------------x:CoreSwitch2

To provide a backup link we still have the 2 core connected, the stack is the vtp root.

At this point every things is alright ^^

But I've worked on a RSTP solution to avoid any problem of connection if something fail.

So If a one of the 2 "root links" fail it switch on the backup link between the 2 cores.

I've also set the stack as the root primary for all the vlans.

So I've configured RSTP on each switch ( the 2 core and the stack) and every things seems okay but, this morning the network was in trouble.

The connection was going down every 30 sec and we were unable to connect more than a minutes.

I've deactivated RSTP and the network recovery and every things was working proprerly.

I don't know what's the problem with RSTP and how to see what's going on. I can see that the stack receiv "VLAN*** Tpology change rcvd on G1/0/*" every 20 - 30 seconds for each VLAN.

I'm very confused, how can I see where is the problem with RSTP ? Why STP doesn't make this problem ?

Does every other switches in the network have to be in rstp mode ?

Is it the convergence time that flood the network ?

Is there an other solution to do the same without STP ?

Help me, please !

Best regard.

8 Replies 8

Does the topology changes propagation can cause this trouble ? Just the 3 switches are un rstp pvst+ and the rest of the network is in default spanning-tree mode.

Any help is welcom

Which switch is your root bridge?

Could you please show us the output from the following commands for each switch.

That makes it easier to troubleshoot your issue.

show spanning-tree

show cdp neighbours (if activated)

The root bridge is the SwitchStack 3750.

Her is the output for 3750 (pvst mode these switch are critical so if I turn pvst mode the network flap):

SwitchStack3750#sh span

VLAN0001

  Spanning tree enabled protocol ieee

  Root ID    Priority    4097

             Address     5057.a84a.b180

             This bridge is the root

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    4097   (priority 4096 sys-id-ext 1)

             Address     5057.a84a.b180

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

             Aging Time  15  sec

Interface           Role Sts Cost      Prio.Nbr Type

------------------- ---- --- --------- -------- --------------------------------

Gi1/0/1             Desg FWD 4         128.1    P2p

Po2                 Desg FWD 4         128.496  P2p

Po3                 Desg FWD 4         128.504  P2p Edge

Po4                 Desg FWD 4         128.512  P2p Edge

Po5                 Desg FWD 4         128.520  P2p Edge

Po6                 Desg FWD 4         128.528  P2p Edge

Po7                 Desg FWD 3         128.536  P2p Edge

Po8                 Desg FWD 4         128.544  P2p Edge

St1                 Desg FWD 4         128.872  P2p

VLAN0002

  Spanning tree enabled protocol ieee

  Root ID    Priority    24578

             Address     5057.a84a.b180

             This bridge is the root

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    24578  (priority 24576 sys-id-ext 2)

             Address     5057.a84a.b180

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

             Aging Time  15  sec

Interface           Role Sts Cost      Prio.Nbr Type

------------------- ---- --- --------- -------- --------------------------------

Gi1/0/1             Desg FWD 4         128.1    P2p

Po2                 Desg FWD 4         128.496  P2p

St1                 Desg FWD 4         128.872  P2p

VLAN0010

  Spanning tree enabled protocol ieee

  Root ID    Priority    24586

             Address     5057.a84a.b180

             This bridge is the root

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    24586  (priority 24576 sys-id-ext 10)

             Address     5057.a84a.b180

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

             Aging Time  15  sec

Interface           Role Sts Cost      Prio.Nbr Type

------------------- ---- --- --------- -------- --------------------------------

Gi1/0/1             Desg FWD 4         128.1    P2p

Po2                 Desg FWD 4         128.496  P2p

St1                 Desg FWD 4         128.872  P2p

VLAN0011

  Spanning tree enabled protocol ieee

  Root ID    Priority    24587

             Address     5057.a84a.b180

             This bridge is the root

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    24587  (priority 24576 sys-id-ext 11)

             Address     5057.a84a.b180

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

             Aging Time  15  sec

Interface           Role Sts Cost      Prio.Nbr Type

------------------- ---- --- --------- -------- --------------------------------

Gi1/0/1             Desg FWD 4         128.1    P2p

Po2                 Desg FWD 4         128.496  P2p

St1                 Desg FWD 4         128.872  P2p

VLAN0012

  Spanning tree enabled protocol ieee

  Root ID    Priority    24588

             Address     5057.a84a.b180

             This bridge is the root

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    24588  (priority 24576 sys-id-ext 12)

             Address     5057.a84a.b180

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

             Aging Time  15  sec

Interface           Role Sts Cost      Prio.Nbr Type

------------------- ---- --- --------- -------- --------------------------------

Gi1/0/1             Desg FWD 4         128.1    P2p

Po2                 Desg FWD 4         128.496  P2p

St1                 Desg FWD 4         128.872  P2p

VLAN0013

  Spanning tree enabled protocol ieee

  Root ID    Priority    24589

             Address     5057.a84a.b180

             This bridge is the root

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    24589  (priority 24576 sys-id-ext 13)

             Address     5057.a84a.b180

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

             Aging Time  15  sec

Interface           Role Sts Cost      Prio.Nbr Type

------------------- ---- --- --------- -------- --------------------------------

Gi1/0/1             Desg FWD 4         128.1    P2p

Po2                 Desg FWD 4         128.496  P2p

St1                 Desg FWD 4         128.872  P2p

VLAN0014

  Spanning tree enabled protocol ieee

  Root ID    Priority    24590

             Address     5057.a84a.b180

             This bridge is the root

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    24590  (priority 24576 sys-id-ext 14)

             Address     5057.a84a.b180

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

             Aging Time  15  sec

Interface           Role Sts Cost      Prio.Nbr Type

------------------- ---- --- --------- -------- --------------------------------

Gi1/0/1             Desg FWD 4         128.1    P2p

Po2                 Desg FWD 4         128.496  P2p

St1                 Desg FWD 4         128.872  P2p

VLAN0015

  Spanning tree enabled protocol ieee

  Root ID    Priority    24591

             Address     5057.a84a.b180

             This bridge is the root

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    24591  (priority 24576 sys-id-ext 15)

             Address     5057.a84a.b180

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

             Aging Time  15  sec

Interface           Role Sts Cost      Prio.Nbr Type

------------------- ---- --- --------- -------- --------------------------------

Gi1/0/1             Desg FWD 4         128.1    P2p

Po2                 Desg FWD 4         128.496  P2p

St1                 Desg FWD 4         128.872  P2p

VLAN0016

  Spanning tree enabled protocol ieee

  Root ID    Priority    24592

             Address     5057.a84a.b180

             This bridge is the root

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    24592  (priority 24576 sys-id-ext 16)

             Address     5057.a84a.b180

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

             Aging Time  15  sec

Interface           Role Sts Cost      Prio.Nbr Type

------------------- ---- --- --------- -------- --------------------------------

Gi1/0/1             Desg FWD 4         128.1    P2p

Po2                 Desg FWD 4         128.496  P2p

St1                 Desg FWD 4         128.872  P2p

VLAN0017

  Spanning tree enabled protocol ieee

  Root ID    Priority    24593

             Address     5057.a84a.b180

             This bridge is the root

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    24593  (priority 24576 sys-id-ext 17)

             Address     5057.a84a.b180

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

             Aging Time  15  sec

Interface           Role Sts Cost      Prio.Nbr Type

------------------- ---- --- --------- -------- --------------------------------

Gi1/0/1             Desg FWD 4         128.1    P2p

Po2                 Desg FWD 4         128.496  P2p

St1                 Desg FWD 4         128.872  P2p

VLAN0018

  Spanning tree enabled protocol ieee

  Root ID    Priority    24594

             Address     5057.a84a.b180

             This bridge is the root

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    24594  (priority 24576 sys-id-ext 18)

             Address     5057.a84a.b180

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

             Aging Time  15  sec

Interface           Role Sts Cost      Prio.Nbr Type

------------------- ---- --- --------- -------- --------------------------------

Gi1/0/1             Desg FWD 4         128.1    P2p

Po2                 Desg FWD 4         128.496  P2p

St1                 Desg FWD 4         128.872  P2p

VLAN0020

  Spanning tree enabled protocol ieee

  Root ID    Priority    24596

             Address     5057.a84a.b180

             This bridge is the root

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    24596  (priority 24576 sys-id-ext 20)

             Address     5057.a84a.b180

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

             Aging Time  15  sec

Interface           Role Sts Cost      Prio.Nbr Type

------------------- ---- --- --------- -------- --------------------------------

Gi1/0/1             Desg FWD 4         128.1    P2p

Po2                 Desg FWD 4         128.496  P2p

St1                 Desg FWD 4         128.872  P2p

VLAN0023

  Spanning tree enabled protocol ieee

  Root ID    Priority    4119

             Address     5057.a84a.b180

             This bridge is the root

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    4119   (priority 4096 sys-id-ext 23)

             Address     5057.a84a.b180

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

             Aging Time  15  sec

Interface           Role Sts Cost      Prio.Nbr Type

------------------- ---- --- --------- -------- --------------------------------

Gi1/0/1             Desg FWD 4         128.1    P2p

Po2                 Desg FWD 4         128.496  P2p

St1                 Desg FWD 4         128.872  P2p

VLAN0025

  Spanning tree enabled protocol ieee

  Root ID    Priority    24601

             Address     5057.a84a.b180

             This bridge is the root

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    24601  (priority 24576 sys-id-ext 25)

             Address     5057.a84a.b180

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

             Aging Time  15  sec

Interface           Role Sts Cost      Prio.Nbr Type

------------------- ---- --- --------- -------- --------------------------------

Gi1/0/1             Desg FWD 4         128.1    P2p

Po2                 Desg FWD 4         128.496  P2p

St1                 Desg FWD 4         128.872  P2p

VLAN0100

  Spanning tree enabled protocol ieee

  Root ID    Priority    24676

             Address     5057.a84a.b180

             This bridge is the root

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    24676  (priority 24576 sys-id-ext 100)

             Address     5057.a84a.b180

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

             Aging Time  15  sec

Interface           Role Sts Cost      Prio.Nbr Type

------------------- ---- --- --------- -------- --------------------------------

Gi1/0/1             Desg FWD 4         128.1    P2p

Po2                 Desg FWD 4         128.496  P2p

St1                 Desg FWD 4         128.872  P2p

VLAN0150

  Spanning tree enabled protocol ieee

  Root ID    Priority    150

             Address     acf2.c52b.9c80

             Cost        23

             Port        1 (GigabitEthernet1/0/1)

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    24726  (priority 24576 sys-id-ext 150)

             Address     5057.a84a.b180

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

             Aging Time  300 sec

Interface           Role Sts Cost      Prio.Nbr Type

------------------- ---- --- --------- -------- --------------------------------

Gi1/0/1             Root FWD 4         128.1    P2p

Gi1/0/13            Desg FWD 19        128.13   P2p

Po2                 Desg FWD 4         128.496  P2p

St1                 Desg FWD 4         128.872  P2p

Gi2/0/13            Desg FWD 19        128.67   P2p

VLAN0200

  Spanning tree enabled protocol ieee

  Root ID    Priority    24776

             Address     5057.a84a.b180

             This bridge is the root

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    24776  (priority 24576 sys-id-ext 200)

             Address     5057.a84a.b180

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

             Aging Time  15  sec

Interface           Role Sts Cost      Prio.Nbr Type

------------------- ---- --- --------- -------- --------------------------------

Gi1/0/1             Desg FWD 4         128.1    P2p

Po2                 Desg FWD 4         128.496  P2p

St1                 Desg FWD 4         128.872  P2p

VLAN0207

  Spanning tree enabled protocol ieee

  Root ID    Priority    24783

             Address     5057.a84a.b180

             This bridge is the root

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    24783  (priority 24576 sys-id-ext 207)

             Address     5057.a84a.b180

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

             Aging Time  15  sec

Interface           Role Sts Cost      Prio.Nbr Type

------------------- ---- --- --------- -------- --------------------------------

Gi1/0/1             Desg FWD 4         128.1    P2p

Po2                 Desg FWD 4         128.496  P2p

St1                 Desg FWD 4         128.872  P2p

VLAN0248

  Spanning tree enabled protocol ieee

  Root ID    Priority    4344

             Address     5057.a84a.b180

             This bridge is the root

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    4344   (priority 4096 sys-id-ext 248)

             Address     5057.a84a.b180

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

             Aging Time  15  sec

Interface           Role Sts Cost      Prio.Nbr Type

------------------- ---- --- --------- -------- --------------------------------

Gi1/0/1             Desg FWD 4         128.1    P2p

Po2                 Desg FWD 4         128.496  P2p

St1                 Desg FWD 4         128.872  P2p

SwitchStack3750#sh cdp nei

Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge

                  S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone,

                  D - Remote, C - CVTA, M - Two-port Mac Relay

Device ID        Local Intrfce     Holdtme    Capability  Platform  Port ID

SwitchCore2

                 Gig 2/0/1         133             R S I  WS-C6509  Gig 4/45

SwitchCore1

                 Gig 1/0/1         177             R S I  WS-C6513  Gig 10/10

-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------

For SwitchCore1:

SwitchCore1#sh span

VLAN0001

  Spanning tree enabled protocol ieee

  Root ID    Priority    4097

             Address     5057.a84a.b180

             Cost        4

             Port        1162 (GigabitEthernet10/10)

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    8193   (priority 8192 sys-id-ext 1)

             Address     0005.74e3.2a80

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

             Aging Time 15

Interface        Role Sts Cost      Prio.Nbr Type

---------------- ---- --- --------- -------- --------------------------------

Gi3/1            Desg FWD 4         128.257  P2p

Gi3/2            Desg FWD 4         128.258  P2p

Gi3/3            Desg FWD 4         128.259  P2p

Gi3/7            Desg FWD 4         128.263  P2p

Gi3/8            Desg FWD 4         128.264  P2p

Fa6/1            Desg FWD 19        128.641  P2p

Fa6/3            Desg FWD 19        128.643  P2p

Fa6/6            Desg FWD 19        128.646  P2p

Fa6/7            Desg FWD 19        128.647  P2p

Fa6/8            Desg FWD 19        128.648  P2p

Fa6/9            Desg FWD 19        128.649  P2p

Fa6/10           Desg FWD 19        128.650  P2p

Fa6/11           Desg FWD 19        128.651  P2p

Fa6/12           Desg FWD 19        128.652  P2p

Fa6/13           Desg FWD 19        128.653  P2p

Fa6/14           Desg FWD 19        128.654  P2p

Fa6/15           Desg FWD 19        128.655  P2p

Fa6/16           Desg FWD 19        128.656  P2p

Fa6/17           Desg FWD 19        128.657  P2p

Fa6/18           Desg FWD 19        128.658  P2p

Fa6/20           Desg FWD 19        128.660  P2p

Fa6/21           Desg FWD 19        128.661  P2p

Fa6/22           Desg FWD 19        128.662  P2p

Fa6/23           Desg FWD 19        128.663  P2p

Fa6/24           Desg FWD 19        128.664  P2p

Fa6/25           Desg FWD 19        128.665  P2p

Fa6/26           Desg FWD 19        128.666  P2p

Fa6/27           Desg FWD 19        128.667  P2p

Fa6/30           Desg FWD 19        128.670  P2p

Fa6/32           Desg FWD 19        128.672  P2p

Fa6/34           Desg FWD 19        128.674  P2p

Fa6/36           Desg FWD 19        128.676  P2p

Fa6/37           Desg FWD 19        128.677  P2p

Fa6/38           Desg FWD 19        128.678  P2p

Fa6/39           Desg FWD 19        128.679  P2p

Fa6/40           Desg FWD 19        128.680  P2p

Fa6/41           Desg FWD 19        128.681  P2p

Fa6/43           Desg FWD 19        128.683  P2p

Fa6/44           Desg FWD 19        128.684  P2p

Fa6/45           Desg FWD 19        128.685  P2p

Fa6/46           Desg FWD 19        128.686  P2p

Fa6/48           Desg FWD 100       128.688  Shr

Fa7/1            Desg FWD 19        128.769  P2p

Fa7/2            Desg FWD 19        128.770  P2p

Fa7/3            Desg FWD 19        128.771  P2p

Fa7/4            Desg FWD 19        128.772  P2p

Fa7/5            Desg FWD 19        128.773  P2p

Fa7/6            Desg FWD 19        128.774  P2p

Fa7/8            Desg FWD 19        128.776  P2p

Fa7/9            Desg FWD 19        128.777  P2p

Fa7/10           Desg FWD 19        128.778  P2p

Fa7/12           Desg FWD 19        128.780  P2p

Fa7/14           Desg FWD 19        128.782  P2p

Fa7/15           Desg FWD 19        128.783  P2p

Fa7/17           Desg FWD 19        128.785  P2p

Fa7/18           Desg FWD 19        128.786  P2p

Fa7/19           Desg FWD 19        128.787  P2p

Fa7/20           Desg FWD 19        128.788  P2p

Fa7/21           Desg FWD 19        128.789  P2p

Fa7/22           Desg FWD 19        128.790  P2p

Fa7/23           Desg FWD 19        128.791  P2p

Fa7/25           Desg FWD 19        128.793  P2p

Fa7/26           Desg FWD 19        128.794  P2p

Fa7/27           Desg FWD 19        128.795  P2p

Fa7/28           Desg FWD 19        128.796  P2p

Fa7/29           Desg FWD 19        128.797  P2p

Fa7/30           Desg FWD 19        128.798  P2p

Fa7/32           Desg FWD 19        128.800  P2p

Fa7/33           Desg FWD 19        128.801  P2p

Fa7/35           Desg FWD 19        128.803  P2p

Fa7/36           Desg FWD 19        128.804  P2p

Fa7/37           Desg FWD 19        128.805  P2p

Fa7/38           Desg FWD 19        128.806  P2p

Fa7/39           Desg FWD 19        128.807  P2p

Fa7/40           Desg FWD 19        128.808  P2p

Fa7/41           Desg FWD 19        128.809  P2p

Fa7/45           Desg FWD 19        128.813  P2p

Fa7/47           Desg FWD 19        128.815  P2p

Fa7/48           Desg FWD 19        128.816  P2p

Fa8/1            Desg FWD 19        128.897  P2p

Fa8/2            Desg FWD 19        128.898  P2p

Fa8/3            Desg FWD 19        128.899  P2p

Fa8/4            Desg FWD 19        128.900  P2p

Fa8/5            Desg FWD 19        128.901  P2p

Fa8/8            Desg FWD 19        128.904  P2p

Fa8/10           Desg FWD 19        128.906  P2p

Fa8/11           Desg FWD 19        128.907  P2p

Fa8/12           Desg FWD 19        128.908  P2p

Fa8/13           Desg FWD 19        128.909  P2p

Fa8/14           Desg FWD 19        128.910  P2p

Fa8/15           Desg FWD 19        128.911  P2p

Fa8/16           Desg FWD 19        128.912  P2p

Fa8/18           Desg FWD 19        128.914  P2p

Fa8/21           Desg FWD 19        128.917  P2p

Fa8/22           Desg FWD 19        128.918  P2p

Fa8/23           Desg FWD 19        128.919  P2p

Fa8/24           Desg FWD 19        128.920  P2p

Fa8/25           Desg FWD 19        128.921  P2p

Fa8/29           Desg FWD 19        128.925  P2p

Fa8/30           Desg FWD 19        128.926  P2p

Fa8/32           Desg FWD 19        128.928  P2p

Fa8/34           Desg FWD 19        128.930  P2p

Fa8/35           Desg FWD 19        128.931  P2p

Fa8/37           Desg FWD 19        128.933  P2p

Fa8/41           Desg FWD 19        128.937  P2p

Fa8/42           Desg FWD 19        128.938  P2p

Fa8/45           Desg FWD 19        128.941  P2p

Fa8/47           Desg FWD 19        128.943  P2p

Fa9/2            Desg FWD 19        128.1026 P2p

Fa9/4            Desg FWD 19        128.1028 P2p

Fa9/7            Desg FWD 19        128.1031 P2p

Fa9/8            Desg FWD 19        128.1032 P2p

Fa9/9            Desg FWD 19        128.1033 P2p

Fa9/13           Desg FWD 19        128.1037 P2p

Fa9/14           Desg FWD 19        128.1038 P2p

Fa9/16           Desg FWD 19        128.1040 P2p

Fa9/17           Desg FWD 19        128.1041 P2p

Fa9/18           Desg FWD 19        128.1042 P2p

Fa9/19           Desg FWD 19        128.1043 P2p

Fa9/20           Desg FWD 19        128.1044 P2p

Fa9/23           Desg FWD 19        128.1047 P2p

Fa9/28           Desg FWD 19        128.1052 Edge P2p

Fa9/30           Desg FWD 19        128.1054 P2p

Fa9/36           Desg FWD 100       128.1060 Shr

Fa9/37           Desg FWD 19        128.1061 P2p

Fa9/39           Desg FWD 19        128.1063 P2p

Fa9/41           Desg FWD 19        128.1065 P2p

Fa9/42           Desg FWD 19        128.1066 P2p

Fa9/44           Desg FWD 19        128.1068 P2p

Fa9/46           Desg FWD 19        128.1070 P2p

Fa9/47           Desg FWD 19        128.1071 P2p

Gi10/1           Desg FWD 4         128.1153 P2p

Gi10/2           Desg FWD 4         128.1154 P2p

Gi10/3           Desg FWD 4         128.1155 P2p

Gi10/4           Desg FWD 4         128.1156 P2p

Gi10/10          Root FWD 4         128.1162 P2p

Gi10/11          Desg FWD 4         128.1163 P2p

Gi10/12          Desg FWD 19        128.1164 P2p

Gi10/15          Desg FWD 100       128.1167 Shr

Gi10/16          Desg FWD 4         128.1168 P2p

Gi10/17          Desg FWD 100       128.1169 Shr

Gi10/18          Desg FWD 4         128.1170 P2p

Gi10/19          Desg FWD 4         128.1171 Edge P2p

Gi10/20          Desg FWD 100       128.1172 Shr

Gi10/21          Desg FWD 4         128.1173 P2p

Gi10/22          Desg FWD 100       128.1174 Shr

Gi10/23          Desg FWD 4         128.1175 P2p

Gi10/24          Desg FWD 100       128.1176 Shr

Gi10/26          Desg FWD 19        128.1178 P2p

Gi10/27          Desg FWD 19        128.1179 P2p

Gi10/28          Desg FWD 4         128.1180 P2p

Gi10/29          Desg FWD 19        128.1181 P2p

Gi10/30          Desg FWD 19        128.1182 P2p

Gi10/31          Desg FWD 19        128.1183 P2p

Gi10/32          Desg FWD 4         128.1184 P2p

Gi10/33          Desg FWD 19        128.1185 P2p

Gi10/34          Desg FWD 100       128.1186 Shr

Gi10/39          Desg FWD 4         128.1191 P2p

Gi10/40          Desg FWD 4         128.1192 P2p

Gi10/41          Desg FWD 4         128.1193 P2p

Gi10/42          Desg FWD 4         128.1194 P2p

Gi10/44          Desg FWD 4         128.1196 P2p

Gi10/45          Desg FWD 4         128.1197 P2p

Gi10/46          Desg FWD 4         128.1198 P2p

Gi10/47          Desg FWD 4         128.1199 P2p

Gi10/48          Desg FWD 4         128.1200 P2p

Fa12/3           Desg FWD 19        128.1411 P2p

Fa12/5           Desg FWD 19        128.1413 P2p

Fa12/7           Desg FWD 19        128.1415 P2p

Fa12/8           Desg FWD 19        128.1416 P2p

Fa12/9           Desg FWD 19        128.1417 P2p

Fa12/10          Desg FWD 19        128.1418 P2p

Fa12/11          Desg FWD 100       128.1419 Shr

Fa12/14          Desg FWD 19        128.1422 P2p

Fa12/16          Desg FWD 19        128.1424 P2p

Fa12/19          Desg FWD 19        128.1427 P2p

Fa12/21          Desg FWD 19        128.1429 P2p

Fa12/22          Desg FWD 100       128.1430 Shr

Fa12/24          Desg FWD 19        128.1432 P2p

Fa12/25          Desg FWD 19        128.1433 P2p

Fa12/26          Desg FWD 19        128.1434 P2p

Fa12/27          Desg FWD 19        128.1435 P2p

Fa12/28          Desg FWD 19        128.1436 P2p

Fa12/29          Desg FWD 19        128.1437 Shr

Fa12/30          Desg FWD 19        128.1438 P2p

Fa12/31          Desg FWD 19        128.1439 P2p

Fa12/32          Desg FWD 19        128.1440 P2p

Fa12/35          Desg FWD 19        128.1443 P2p

Fa12/37          Desg FWD 19        128.1445 P2p

Fa12/38          Desg FWD 19        128.1446 P2p

Fa12/40          Desg FWD 19        128.1448 P2p

Fa12/41          Desg FWD 19        128.1449 P2p

Fa12/42          Desg FWD 19        128.1450 P2p

Fa12/43          Desg FWD 19        128.1451 P2p

Fa12/44          Desg FWD 19        128.1452 P2p

Fa12/48          Desg FWD 19        128.1456 P2p

Fa13/1           Desg FWD 19        128.1537 P2p

Fa13/2           Desg FWD 19        128.1538 P2p

Fa13/5           Desg FWD 19        128.1541 P2p

Fa13/6           Desg FWD 19        128.1542 P2p

Fa13/7           Desg FWD 19        128.1543 P2p

Fa13/9           Desg FWD 19        128.1545 P2p

Fa13/11          Desg FWD 19        128.1547 P2p

Fa13/13          Desg FWD 19        128.1549 P2p

Fa13/16          Desg FWD 19        128.1552 P2p

Fa13/17          Desg FWD 19        128.1553 P2p

Fa13/19          Desg FWD 19        128.1555 P2p

Fa13/24          Desg FWD 19        128.1560 P2p

Fa13/25          Desg FWD 19        128.1561 P2p

Fa13/26          Desg FWD 19        128.1562 P2p

Fa13/27          Desg FWD 19        128.1563 P2p

Fa13/28          Desg FWD 19        128.1564 P2p

Fa13/29          Desg FWD 19        128.1565 P2p

Fa13/30          Desg FWD 19        128.1566 P2p

Fa13/32          Desg FWD 19        128.1568 P2p

Fa13/33          Desg FWD 19        128.1569 P2p

Fa13/34          Desg FWD 19        128.1570 P2p

Fa13/35          Desg FWD 100       128.1571 Shr

Fa13/37          Desg FWD 19        128.1573 P2p

Fa13/38          Desg FWD 19        128.1574 P2p

Fa13/39          Desg FWD 19        128.1575 P2p

Fa13/40          Desg FWD 19        128.1576 P2p

Fa13/43          Desg FWD 19        128.1579 P2p

Fa13/44          Desg FWD 19        128.1580 P2p

Fa13/47          Desg FWD 19        128.1583 P2p

Po5              Desg FWD 3         128.1667 P2p

Po6              Desg FWD 3         128.1668 P2p

Po2              Desg FWD 12        128.1676 Edge P2p

VLAN0002

  Spanning tree enabled protocol ieee

  Root ID    Priority    24578

             Address     5057.a84a.b180

             Cost        4

             Port        1162 (GigabitEthernet10/10)

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    32770  (priority 32768 sys-id-ext 2)

             Address     0005.74e3.2a80

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

             Aging Time 15

Interface        Role Sts Cost      Prio.Nbr Type

---------------- ---- --- --------- -------- --------------------------------

Gi3/1            Desg FWD 4         128.257  P2p

Gi3/2            Desg FWD 4         128.258  P2p

Gi3/3            Desg FWD 4         128.259  P2p

Gi3/7            Desg FWD 4         128.263  P2p

Gi3/8            Desg FWD 4         128.264  P2p

Fa6/1            Desg FWD 19        128.641  P2p

Fa6/3            Desg FWD 19        128.643  P2p

Fa6/6            Desg FWD 19        128.646  P2p

Fa6/7            Desg FWD 19        128.647  P2p

Fa6/8            Desg FWD 19        128.648  P2p

Fa6/9            Desg FWD 19        128.649  P2p

Fa6/10           Desg FWD 19        128.650  P2p

Fa6/11           Desg FWD 19        128.651  P2p

Fa6/12           Desg FWD 19        128.652  P2p

Fa6/13           Desg FWD 19        128.653  P2p

Fa6/14           Desg FWD 19        128.654  P2p

Fa6/15           Desg FWD 19        128.655  P2p

Fa6/16           Desg FWD 19        128.656  P2p

Fa6/17           Desg FWD 19        128.657  P2p

Fa6/18           Desg FWD 19        128.658  P2p

Fa6/20           Desg FWD 19        128.660  P2p

Fa6/21           Desg FWD 19        128.661  P2p

Fa6/22           Desg FWD 19        128.662  P2p

Fa6/23           Desg FWD 19        128.663  P2p

Fa6/24           Desg FWD 19        128.664  P2p

Fa6/25           Desg FWD 19        128.665  P2p

Fa6/26           Desg FWD 19        128.666  P2p

Fa6/27           Desg FWD 19        128.667  P2p

Fa6/30           Desg FWD 19        128.670  P2p

Fa6/32           Desg FWD 19        128.672  P2p

Fa6/34           Desg FWD 19        128.674  P2p

Fa6/36           Desg FWD 19        128.676  P2p

Fa6/37           Desg FWD 19        128.677  P2p

Fa6/38           Desg FWD 19        128.678  P2p

Fa6/39           Desg FWD 19        128.679  P2p

Fa6/40           Desg FWD 19        128.680  P2p

Fa6/41           Desg FWD 19        128.681  P2p

Fa6/43           Desg FWD 19        128.683  P2p

Fa6/44           Desg FWD 19        128.684  P2p

Fa6/45           Desg FWD 19        128.685  P2p

Fa6/46           Desg FWD 19        128.686  P2p

Fa6/48           Desg FWD 100       128.688  Shr

Fa7/1            Desg FWD 19        128.769  P2p

Fa7/2            Desg FWD 19        128.770  P2p

Fa7/3            Desg FWD 19        128.771  P2p

Fa7/4            Desg FWD 19        128.772  P2p

Fa7/5            Desg FWD 19        128.773  P2p

Fa7/6            Desg FWD 19        128.774  P2p

Fa7/8            Desg FWD 19        128.776  P2p

Fa7/9            Desg FWD 19        128.777  P2p

Fa7/10           Desg FWD 19        128.778  P2p

Fa7/12           Desg FWD 19        128.780  P2p

Fa7/14           Desg FWD 19        128.782  P2p

Fa7/15           Desg FWD 19        128.783  P2p

Fa7/17           Desg FWD 19        128.785  P2p

Fa7/18           Desg FWD 19        128.786  P2p

Fa7/19           Desg FWD 19        128.787  P2p

Fa7/20           Desg FWD 19        128.788  P2p

Fa7/21           Desg FWD 19        128.789  P2p

Fa7/22           Desg FWD 19        128.790  P2p

Fa7/23           Desg FWD 19        128.791  P2p

Fa7/25           Desg FWD 19        128.793  P2p

Fa7/26           Desg FWD 19        128.794  P2p

Fa7/27           Desg FWD 19        128.795  P2p

Fa7/28           Desg FWD 19        128.796  P2p

Fa7/29           Desg FWD 19        128.797  P2p

Fa7/30           Desg FWD 19        128.798  P2p

Fa7/32           Desg FWD 19        128.800  P2p

Fa7/33           Desg FWD 19        128.801  P2p

Fa7/35           Desg FWD 19        128.803  P2p

Fa7/36           Desg FWD 19        128.804  P2p

Fa7/37           Desg FWD 19        128.805  P2p

Fa7/38           Desg FWD 19        128.806  P2p

Fa7/39           Desg FWD 19        128.807  P2p

Fa7/40           Desg FWD 19        128.808  P2p

Fa7/41           Desg FWD 19        128.809  P2p

Fa7/45           Desg FWD 19        128.813  P2p

Fa7/47           Desg FWD 19        128.815  P2p

Fa7/48           Desg FWD 19        128.816  P2p

Fa8/1            Desg FWD 19        128.897  P2p

Fa8/2            Desg FWD 19        128.898  P2p

Fa8/3            Desg FWD 19        128.899  P2p

Fa8/4            Desg FWD 19        128.900  P2p

Fa8/5            Desg FWD 19        128.901  P2p

Fa8/8            Desg FWD 19        128.904  P2p

Fa8/10           Desg FWD 19        128.906  P2p

Fa8/11           Desg FWD 19        128.907  P2p

Fa8/12           Desg FWD 19        128.908  P2p

Fa8/13           Desg FWD 19        128.909  P2p

Fa8/14           Desg FWD 19        128.910  P2p

Fa8/15           Desg FWD 19        128.911  P2p

Fa8/16           Desg FWD 19        128.912  P2p

Fa8/18           Desg FWD 19        128.914  P2p

Fa8/21           Desg FWD 19        128.917  P2p

Fa8/22           Desg FWD 19        128.918  P2p

Fa8/23           Desg FWD 19        128.919  P2p

Fa8/24           Desg FWD 19        128.920  P2p

Fa8/25           Desg FWD 19        128.921  P2p

Fa8/29           Desg FWD 19        128.925  P2p

Fa8/30           Desg FWD 19        128.926  P2p

Fa8/32           Desg FWD 19        128.928  P2p

Fa8/34           Desg FWD 19        128.930  P2p

Fa8/35           Desg FWD 19        128.931  P2p

Fa8/37           Desg FWD 19        128.933  P2p

Fa8/41           Desg FWD 19        128.937  P2p

Fa8/42           Desg FWD 19        128.938  P2p

Fa8/45           Desg FWD 19        128.941  P2p

Fa8/47           Desg FWD 19        128.943  P2p

Fa9/2            Desg FWD 19        128.1026 P2p

Fa9/4            Desg FWD 19        128.1028 P2p

Fa9/7            Desg FWD 19        128.1031 P2p

Fa9/8            Desg FWD 19        128.1032 P2p

Fa9/9            Desg FWD 19        128.1033 P2p

Fa9/13           Desg FWD 19        128.1037 P2p

Fa9/14           Desg FWD 19        128.1038 P2p

Fa9/16           Desg FWD 19        128.1040 P2p

Fa9/17           Desg FWD 19        128.1041 P2p

Fa9/18           Desg FWD 19        128.1042 P2p

Fa9/19           Desg FWD 19        128.1043 P2p

Fa9/20           Desg FWD 19        128.1044 P2p

Fa9/23           Desg FWD 19        128.1047 P2p

Fa9/36           Desg FWD 100       128.1060 Shr

Fa9/37           Desg FWD 19        128.1061 P2p

Fa9/39           Desg FWD 19        128.1063 P2p

Fa9/41           Desg FWD 19        128.1065 P2p

Fa9/42           Desg FWD 19        128.1066 P2p

Fa9/44           Desg FWD 19        128.1068 P2p

Fa9/46           Desg FWD 19        128.1070 P2p

Fa9/47           Desg FWD 19        128.1071 P2p

Gi10/10          Root FWD 4         128.1162 P2p

Gi10/11          Desg FWD 4         128.1163 P2p

Gi10/12          Desg FWD 19        128.1164 P2p

Gi10/15          Desg FWD 100       128.1167 Shr

Gi10/16          Desg FWD 4         128.1168 P2p

Gi10/17          Desg FWD 100       128.1169 Shr

Gi10/18          Desg FWD 4         128.1170 P2p

Gi10/20          Desg FWD 100       128.1172 Shr

Gi10/21          Desg FWD 4         128.1173 P2p

Gi10/22          Desg FWD 100       128.1174 Shr

Gi10/23          Desg FWD 4         128.1175 P2p

Gi10/24          Desg FWD 100       128.1176 Shr

Gi10/26          Desg FWD 19        128.1178 P2p

Gi10/27          Desg FWD 19        128.1179 P2p

Gi10/28          Desg FWD 4         128.1180 P2p

Gi10/29          Desg FWD 19        128.1181 P2p

Gi10/30          Desg FWD 19        128.1182 P2p

Gi10/31          Desg FWD 19        128.1183 P2p

Gi10/32          Desg FWD 4         128.1184 P2p

Gi10/33          Desg FWD 19        128.1185 P2p

Gi10/34          Desg FWD 100       128.1186 Shr

Gi10/39          Desg FWD 4         128.1191 P2p

Gi10/40          Desg FWD 4         128.1192 P2p

Gi10/41          Desg FWD 4         128.1193 P2p

Gi10/42          Desg FWD 4         128.1194 P2p

Gi10/44          Desg FWD 4         128.1196 P2p

Gi10/45          Desg FWD 4         128.1197 P2p

Gi10/46          Desg FWD 4         128.1198 P2p

Gi10/47          Desg FWD 4         128.1199 P2p

Gi10/48          Desg FWD 4         128.1200 P2p

Fa12/3           Desg FWD 19        128.1411 P2p

Fa12/5           Desg FWD 19        128.1413 P2p

Fa12/7           Desg FWD 19        128.1415 P2p

Fa12/8           Desg FWD 19        128.1416 P2p

Fa12/9           Desg FWD 19        128.1417 P2p

Fa12/10          Desg FWD 19        128.1418 P2p

Fa12/11          Desg FWD 100       128.1419 Shr

Fa12/14          Desg FWD 19        128.1422 P2p

Fa12/16          Desg FWD 19        128.1424 P2p

Fa12/19          Desg FWD 19        128.1427 P2p

Fa12/21          Desg FWD 19        128.1429 P2p

Fa12/22          Desg FWD 100       128.1430 Shr

Fa12/24          Desg FWD 19        128.1432 P2p

Fa12/25          Desg FWD 19        128.1433 P2p

Fa12/26          Desg FWD 19        128.1434 P2p

Fa12/27          Desg FWD 19        128.1435 P2p

Fa12/28          Desg FWD 19        128.1436 P2p

Fa12/29          Desg FWD 19        128.1437 Shr

Fa12/30          Desg FWD 19        128.1438 P2p

Fa12/31          Desg FWD 19        128.1439 P2p

Fa12/32          Desg FWD 19        128.1440 P2p

Fa12/35          Desg FWD 19        128.1443 P2p

Fa12/37          Desg FWD 19        128.1445 P2p

Fa12/38          Desg FWD 19        128.1446 P2p

Fa12/40          Desg FWD 19        128.1448 P2p

Fa12/41          Desg FWD 19        128.1449 P2p

Fa12/42          Desg FWD 19        128.1450 P2p

Fa12/43          Desg FWD 19        128.1451 P2p

Fa12/44          Desg FWD 19        128.1452 P2p

Fa12/48          Desg FWD 19        128.1456 P2p

Fa13/1           Desg FWD 19        128.1537 P2p

Fa13/2           Desg FWD 19        128.1538 P2p

Fa13/5           Desg FWD 19        128.1541 P2p

Fa13/6           Desg FWD 19        128.1542 P2p

Fa13/7           Desg FWD 19        128.1543 P2p

Fa13/9           Desg FWD 19        128.1545 P2p

Fa13/11          Desg FWD 19        128.1547 P2p

Fa13/13          Desg FWD 19        128.1549 P2p

Fa13/16          Desg FWD 19        128.1552 P2p

Fa13/17          Desg FWD 19        128.1553 P2p

Fa13/19          Desg FWD 19        128.1555 P2p

Fa13/24          Desg FWD 19        128.1560 P2p

Fa13/25          Desg FWD 19        128.1561 P2p

Fa13/26          Desg FWD 19        128.1562 P2p

Fa13/27          Desg FWD 19        128.1563 P2p

Fa13/28          Desg FWD 19        128.1564 P2p

Fa13/29          Desg FWD 19        128.1565 P2p

Fa13/30          Desg FWD 19        128.1566 P2p

Fa13/32          Desg FWD 19        128.1568 P2p

Fa13/33          Desg FWD 19        128.1569 P2p

Fa13/34          Desg FWD 19        128.1570 P2p

Fa13/35          Desg FWD 100       128.1571 Shr

Fa13/37          Desg FWD 19        128.1573 P2p

Fa13/38          Desg FWD 19        128.1574 P2p

Fa13/39          Desg FWD 19        128.1575 P2p

Fa13/40          Desg FWD 19        128.1576 P2p

Fa13/43          Desg FWD 19        128.1579 P2p

Fa13/44          Desg FWD 19        128.1580 P2p

Fa13/47          Desg FWD 19        128.1583 P2p

It's a huge output so I've juste past for vlan1 and vlan2, the others seems similar :-)

SwitchCore1#sh cdp nei

Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge

                  S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone

Device ID        Local Intrfce     Holdtme    Capability  Platform  Port ID

SwitchStack3750

                 Gi 4/45           147          R S I       WS-C3750X-Gig 1/0/1

SwitchCore2

                 Gi 1/1           160           R S I        WS-C6509-Gig1/1

---------------------------------------------------------------------------------------------------------------------------------------------------------------------------

For SwitchCore2:

SwitchCore2#sh span

(Just vlan1 , a lot of port in trunk mode...)

VLAN0001

  Spanning tree enabled protocol ieee

  Root ID    Priority    4097

             Address     5057.a84a.b180

             Cost        4

             Port        1665 (Port-channel2)

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    16385  (priority 16384 sys-id-ext 1)

             Address     000e.d69f.4e40

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

             Aging Time 15

Interface        Role Sts Cost      Prio.Nbr Type

---------------- ---- --- --------- -------- --------------------------------

Gi4/3            Desg FWD 4         128.387  P2p

Gi4/4            Desg FWD 19        128.388  P2p

Gi4/5            Desg FWD 19        128.389  P2p

Gi4/6            Desg FWD 4         128.390  P2p

Gi4/12           Desg FWD 19        128.396  P2p

Gi4/15           Desg FWD 4         128.399  P2p

Gi4/17           Desg FWD 19        128.401  P2p

Gi4/18           Desg FWD 4         128.402  P2p

Gi4/19           Desg FWD 4         128.403  P2p

Gi4/21           Desg FWD 19        128.405  P2p

Gi4/22           Desg FWD 4         128.406  P2p

Gi4/23           Desg FWD 4         128.407  P2p

Gi4/24           Desg FWD 19        128.408  P2p

Gi4/25           Desg FWD 4         128.409  P2p

Gi4/26           Desg FWD 19        128.410  P2p

Gi4/27           Desg FWD 19        128.411  P2p

Gi4/28           Desg FWD 4         128.412  P2p

Gi4/29           Desg FWD 19        128.413  P2p

Gi4/30           Desg FWD 4         128.414  P2p

Gi4/31           Desg FWD 19        128.415  P2p

Gi4/32           Desg FWD 4         128.416  P2p

Gi4/34           Desg FWD 4         128.418  P2p

Gi4/35           Desg FWD 4         128.419  P2p

Gi4/36           Desg FWD 4         128.420  P2p

Gi4/38           Desg FWD 4         128.422  P2p

Gi4/40           Desg FWD 4         128.424  P2p

Fa5/2            Desg FWD 19        128.514  P2p

Fa5/3            Desg FWD 19        128.515  P2p

Fa5/5            Desg FWD 19        128.517  P2p

Fa5/6            Desg FWD 19        128.518  P2p

Fa5/7            Desg FWD 19        128.519  P2p

Fa5/8            Desg FWD 19        128.520  P2p

Fa5/9            Desg FWD 19        128.521  P2p

Fa5/10           Desg FWD 19        128.522  P2p

Fa5/12           Desg FWD 19        128.524  P2p

Fa5/13           Desg FWD 19        128.525  P2p

Fa5/14           Desg FWD 19        128.526  P2p

Fa5/16           Desg FWD 19        128.528  P2p

Fa5/19           Desg FWD 19        128.531  P2p

Fa5/22           Desg FWD 19        128.534  P2p

Fa5/24           Desg FWD 19        128.536  P2p

Fa5/25           Desg FWD 19        128.537  P2p

Fa5/26           Desg FWD 19        128.538  P2p

Fa5/27           Desg FWD 19        128.539  P2p

Fa5/28           Desg FWD 19        128.540  P2p

Fa5/29           Desg FWD 19        128.541  P2p

Fa5/30           Desg FWD 19        128.542  P2p

Fa5/31           Desg FWD 19        128.543  P2p

Fa5/33           Desg FWD 19        128.545  P2p

Fa5/41           Desg FWD 19        128.553  P2p

Fa5/42           Desg FWD 19        128.554  P2p

Fa5/43           Desg FWD 19        128.555  P2p

Fa5/45           Desg FWD 19        128.557  P2p

Fa5/46           Desg FWD 19        128.558  P2p

Fa5/48           Desg FWD 19        128.560  P2p

Fa6/1            Desg FWD 100       128.641  Shr

Fa6/2            Desg FWD 19        128.642  P2p

Fa6/3            Desg FWD 19        128.643  P2p

Fa6/4            Desg FWD 19        128.644  P2p

Fa6/10           Desg FWD 19        128.650  P2p

Fa6/12           Desg FWD 19        128.652  P2p

Fa6/14           Desg FWD 19        128.654  P2p

Fa6/15           Desg FWD 19        128.655  P2p

Fa6/16           Desg FWD 19        128.656  P2p

Fa6/17           Desg FWD 19        128.657  P2p

Fa6/18           Desg FWD 19        128.658  P2p

Fa6/21           Desg FWD 19        128.661  P2p

Fa6/22           Desg FWD 19        128.662  P2p

Fa6/24           Desg FWD 19        128.664  P2p

Fa6/25           Desg FWD 19        128.665  P2p

Fa6/27           Desg FWD 19        128.667  P2p

Fa6/28           Desg FWD 19        128.668  P2p

Fa6/29           Desg FWD 19        128.669  P2p

Fa6/31           Desg FWD 19        128.671  P2p

Fa6/32           Desg FWD 19        128.672  P2p

Fa6/34           Desg FWD 19        128.674  P2p

Fa6/35           Desg FWD 19        128.675  P2p

Fa6/36           Desg FWD 19        128.676  P2p

Fa6/38           Desg FWD 19        128.678  P2p

Fa6/41           Desg FWD 19        128.681  P2p

Fa6/43           Desg FWD 19        128.683  P2p

Fa6/46           Desg FWD 19        128.686  P2p

Fa6/48           Desg FWD 19        128.688  P2p

Fa7/1            Desg FWD 19        128.769  P2p

Fa7/2            Desg FWD 19        128.770  P2p

Fa7/3            Desg FWD 19        128.771  P2p

Fa7/5            Desg FWD 19        128.773  P2p

Fa7/9            Desg FWD 19        128.777  P2p

Fa7/11           Desg FWD 19        128.779  P2p

Fa7/12           Desg FWD 100       128.780  P2p

Fa7/15           Desg FWD 19        128.783  P2p

Fa7/16           Desg FWD 19        128.784  P2p

Fa7/17           Desg FWD 19        128.785  P2p

Fa7/18           Desg FWD 19        128.786  P2p

Fa7/19           Desg FWD 19        128.787  P2p

Fa7/20           Desg FWD 19        128.788  P2p

Fa7/23           Desg FWD 19        128.791  P2p

Fa7/24           Desg FWD 19        128.792  P2p

Fa7/32           Desg FWD 19        128.800  P2p

Fa7/42           Desg FWD 19        128.810  P2p

Fa7/48           Desg FWD 19        128.816  P2p

Fa8/1            Desg FWD 19        128.897  P2p

Fa8/3            Desg FWD 19        128.899  P2p

Fa8/4            Desg FWD 19        128.900  P2p

Fa8/5            Desg FWD 19        128.901  P2p

Fa8/6            Desg FWD 19        128.902  P2p

Fa8/7            Desg FWD 19        128.903  P2p

Fa8/9            Desg FWD 100       128.905  Shr

Fa8/10           Desg FWD 19        128.906  P2p

Fa8/11           Desg FWD 19        128.907  P2p

Fa8/12           Desg FWD 19        128.908  P2p

Fa8/13           Desg FWD 19        128.909  P2p

Fa8/15           Desg FWD 19        128.911  P2p

Fa8/16           Desg FWD 19        128.912  P2p

Fa8/17           Desg FWD 19        128.913  P2p

Fa8/20           Desg FWD 19        128.916  P2p

Fa8/21           Desg FWD 100       128.917  Shr

Fa8/22           Desg FWD 19        128.918  P2p

Fa8/23           Desg FWD 19        128.919  P2p

Fa8/24           Desg FWD 100       128.920  Shr

Fa8/29           Desg FWD 19        128.925  P2p

Fa8/32           Desg FWD 19        128.928  P2p

Fa8/34           Desg FWD 19        128.930  P2p

Fa8/38           Desg FWD 19        128.934  P2p

Fa8/41           Desg FWD 100       128.937  Shr

Fa8/43           Desg FWD 19        128.939  P2p

Po2              Root FWD 4         128.1665 P2p

Po16             Desg FWD 4         128.1670 P2p

Po1              Desg FWD 4         128.1671 P2p

Po5              Desg FWD 3         128.1673 P2p

SwitchCore2#sh cdp nei

Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge

                  S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone

Device ID        Local Intrfce     Holdtme    Capability  Platform  Port ID

SwitchStack3750

                 Gi 10/10           147          R S I       WS-C3750X-Gig 2/0/1

SwitchCore1

                 Gi 1/1           160           R S I        WS-C6513-Gig1/1

And in pvst mode the network is stable but when Rapid-pvst is enabled the network flap (connected for about a minutes then 30 sec disconnected , reconnection for a minute again,...)

Thanks for your replie !!

NB: Here we can't se any "alt" port or "bckp" port because these link were down.

The alternative port is the link between the 2 cores

Here some news !

I've juste seen that some spanning-tree portfast was enabled on the link between core1 and the stack !

On the port of the stack the gig 1/0/1 have spann-tree protfast

and on the core 1 the port gig 10/10 have also spann-tree portfast enabled !

I know that's not a good practice and this can cause loops, these port are in trunking mode.

In rstp, port with spanning-tree portfast enabled make an edge port that doesn't participate in spanning-tree but if it receive BPDU it switch to non-edge port. Here spanning-tree portfast is enabled on the root bridge (the stack) and the core, so no BPDU are send by the root and the port is in forwarding state.

Can it be the reason of my problem ? I'm not sure about that but I look after it.

Anyone ?

Please someone help me.

Hello Alex,

It is hard to say what is going on because we do not know topology and also switch configuration. Why are you using different STP modes on each switch, it can cause a lot of problems. I would configure same STP modes on each switch and then step by step try to diagnose a problem if any.

Best Regards

Please rate all helpful posts and close solved questions

Best Regards Please rate all helpful posts and close solved questions

Hello,

This is the probleme, has a student I can just   configure these 3 switches, so I can't configure RSTP on the others.   It's kind difficult to test or diagnose (these are critical). I post  the  configuration of the switches to help.

My goal is to implement RSTP only between these 3 switches and keep compatibility with the rest of the network.

I'm still studying the RSTP and how convergence work in detail but everythings seems better and faster than the STP.

Here the config file (as they work actually with STP, if I change to RSTP the network flap)

Thanks for your answer !!

Best regards

PS: I've found something new : there was a loop in the network (an interface on vlan 10 was enabled), since the day we've made the migration. Maybe this is the problem ?

Sorry for my bad english

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