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Spanning tree help

Hi All ,

               I have got 2 UD switch  block ( Multilayer switch 0 , Multilayer switch 1 ) , Access layer switch 2950 24 port switch which is operated for 2 different floor ( Access layer 2950 sw1 at Frist floor & Access layer 2950 Sw2 at 2nd floor ) ,

ML SW 1 to AL SW 1 --> Fa0/1 --> Fa0/1

ML SW 1 to AL SW 2 --> Fa 0/2 --> Fa0/1

ML Sw 2 to AL SW 1 --> Fa0/1-- > Fa0/2

ML SW 2 toAL Sw 2  --> Fa0/2 --> Fa 0/2

My all switch operating r running in VTP transparent mode , My network is operating with 3 vlan

Vlan 10 : support  : 30 user

Vlan 20 : development : 18 user

Vlan 30 : Network management

trunking between both Multilayer switch allow only VLAN 30

But  my objective is to have both uplink connecting to Multilayer switch  from access layer sw should be in forwarding state ,

For eg Vlan 20 has 18 user , so i am keeping AL 2950 Sw2 as root bridge , so my both uplink is in forwarding state

VLAN0020
  Spanning tree enabled protocol ieee
  Root ID    Priority    24596
             Address     000D.BD10.A8E9
             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     000D.BD10.A8E9
             Hello Time  2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time  20

Interface        Role Sts Cost      Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Fa0/1            Desg FWD 19        128.1    P2p
Fa0/2            Desg FWD 19        128.2    P2p

But for Vlan 10 has 30 user , I am keeping al 2950 Sw1 as root bridge , in AL SW 1 both uplink or in forwarding state , but in AL Sw2 port connecting to ML SW1 is in forwarding state , port connecting to ML sw2 is blocking state

alsw2#sh spanning-tree
VLAN0010
  Spanning tree enabled protocol ieee
  Root ID    Priority    24586
             Address     0001.636D.8A6A
             Cost        19
             Port        1(FastEthernet0/1)
             Hello Time  2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    24586  (priority 24576 sys-id-ext 10)
             Address     000D.BD10.A8E9
             Hello Time  2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time  20

Interface        Role Sts Cost      Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Fa0/1            Root FWD 19        128.1    P2p
Fa0/2            Altn BLK 19        128.2    P2p

I have HSRP priority high for VLan 10 on ML Sw2 , and for Van 20 ML sw1 is high , If my access layer switch2  port fa0/2 is in blocking mode , my end user may nt get connected to Ml Sw2 due trunk port is in blocking mode ,

   Suggest me good STP design on this scenario ....

Else i want to use my ML SW 1  or SW 2 as root bridge for both VLAN ,

or else trunk port connecting between ML SW 1 & ML SW 2 should permit vlan 10 , 20 along with vlan 30 ..

1 REPLY

Re: Spanning tree help

Kindly reply me , whether Keeping ML Sw1  or ML Sw2 as root switch would be better choice  for this setup ..

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