Help - L2 redundancy config?

[accurisit]

Hi,

As per the attached diagram:

How do I configure the 2 ports on the 3560 (Ports 6 & 7) and the connected ports on each of the 2960 switches (Port 25) to provide redundancy.

If the uplink from Switch A dies then I need the traffic to flow through the trunk and utilise the uplink on Switch B with minimal delay (milliseconds).

Many thanks

Simon...

Message was edited by: Simon Scott - Updated Diagram

[Reza Sharifi]

Hi,

Are the servers connected to both 2960s using Etherchannel?  If that is the case you can't have an Etherchannel with 2 links, one link connecting to one 2960 and the other one to the other 2960. If these are 2960 S series switches, you can stack them and then the Etherchannel will work fine since both switches logically would look as one.

HTH

[accurisit]

The switches are basic L2 2960 models so no option to Stack them.

I've amended the diagram to avoid confusion over 'Redundancy' and also to amend the Subnet Mask of the 3560.

If I remove the uplink cable from Switch A it takes 30 to 50 seconds for the Uplink from Switch B to become active

But...

If the uplink cabled from Switch B is removed first, then the Uplink cable from Switch A is removed followed by the Uplink cable from Switch B replaced, the connection comes back immediately.

I've added 'spanning-tree port fast' on the 2 uplink ports on the 3560 but no difference.

Any help would be gratefully received.

Simon...

[cadet alain]

Hi,

you should use RPVST+ on all switches  instead of PVST+ (which you are surely using from the 50 sec downtime you described) with the command spanning-tree mode rapid.

Do this during a scheduled  period because it will cause some downtime.

Can you also provide the output from sh sapnning-tree vlan 10 on the 3 switches.

Regards.

Alain

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[accurisit]

Thanks Alain,

CISCO 3560 SWITCH

Cisco3560#sh spanning-tree vlan 10

VLAN1810

  Spanning tree enabled protocol rstp

  Root ID    Priority    34578

             Address     3cdf.1ecc.7980

             This bridge is the root

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

  Bridge ID  Priority    34578  (priority 32768 sys-id-ext 10)

             Address     3cdf.1ecc.7980

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

             Aging Time 300

Interface        Role Sts Cost      Prio.Nbr Type

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

Gi0/6            Desg FWD 4         128.6    P2p Peer(STP)

Gi0/7            Desg FWD 4         128.7    P2p Peer(STP)

Gi0/17           Desg FWD 19        128.17   P2p

Gi0/21           Desg FWD 19        128.21   P2p

Gi0/22           Desg FWD 19        128.22   P2p

Gi0/23           Desg FWD 19        128.23   P2p

Gi0/24           Desg FWD 19        128.24   P2p

Cisco3560#

CISCO 2960 SWITCH A

co15-pri-sw#sh spanning-tree vlan 10

VLAN1810

  Spanning tree enabled protocol rstp

  Root ID    Priority    34578

             Address     3cdf.1ecc.7980

             Cost        4

             Port        26 (GigabitEthernet0/2)

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

  Bridge ID  Priority    34578  (priority 32768 sys-id-ext 10)

             Address     5897.1e4d.3500

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

             Aging Time  300 sec

Interface           Role Sts Cost      Prio.Nbr Type

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

Fa0/3               Desg FWD 19        128.3    P2p

Fa0/4               Desg FWD 19        128.4    P2p

Gi0/1               Altn BLK 4         128.25   P2p

Gi0/2               Root FWD 4         128.26   P2p

co15-pri-sw#

CISCO 2960 SWITCH B

co15-sec-sw#sh spanning-tree vlan 10

VLAN1810

  Spanning tree enabled protocol rstp

  Root ID    Priority    34578

             Address     3cdf.1ecc.7980

             Cost        4

             Port        26 (GigabitEthernet0/2)

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

  Bridge ID  Priority    34578  (priority 32768 sys-id-ext 10)

             Address     5478.1a96.d980

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

             Aging Time  300 sec

Interface           Role Sts Cost      Prio.Nbr Type

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

Fa0/3               Desg FWD 19        128.3    P2p

Fa0/4               Desg FWD 19        128.4    P2p

Gi0/1               Desg FWD 4         128.25   P2p

Gi0/2               Root FWD 4         128.26   P2p

co15-sec-sw#

[cadet alain]

Hi,

You already have RPVST+, did you make the change already ?

can you post sh cdp nei on the 2960s and sh int trunk.

Regards.

Alain

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[accurisit]

I already made the change.

CISCO 2960 SWITCH A

co15-pri-sw#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

co15-sec-sw.alcatel-lucent.com

                 Gig 0/1           162              S I   WS-C2960- Gig 0/1

Cisco3560        Gig 0/2           154             R S I  WS-C3560G Gig 0/6

co15-pri-sw#sh int trunk

Port        Mode             Encapsulation  Status        Native vlan

Gi0/1       on               802.1q         trunking      1

Port        Vlans allowed on trunk

Gi0/1       10,50

Port        Vlans allowed and active in management domain

Gi0/1       10,50

Port        Vlans in spanning tree forwarding state and not pruned

Gi0/1       50

co15-pri-sw#

CISCO 2960 SWITCH B

co15-sec-sw#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

Cisco3560        Gig 0/2           153             R S I  WS-C3560G Gig 0/7

co15-pri-sw.alcatel-lucent.com

                 Gig 0/1           164              S I   WS-C2960- Gig 0/1

co15-sec-sw#sh int trunk

Port        Mode             Encapsulation  Status        Native vlan

Gi0/1       on               802.1q         trunking      1

Port        Vlans allowed on trunk

Gi0/1       10,50

Port        Vlans allowed and active in management domain

Gi0/1       10,50

Port        Vlans in spanning tree forwarding state and not pruned

Gi0/1       10,50

co15-sec-sw#

[cadet alain]

Hi,

ok so now you should see less downtime  for failover ? don't enable Portfast on the trunk links between the 2 2960s as well as on the uplink ports.

Regards.

Alain

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[accurisit]

It's down to 35seconds - Is that about the best I'm going to get?

Simon...

[cadet alain]

Hi,

Cisco3560#sh spanning-tree vlan 10

VLAN1810

  Spanning tree enabled protocol rstp

  Root ID    Priority    34578

             Address     3cdf.1ecc.7980

             This bridge is the root

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

  Bridge ID  Priority    34578  (priority 32768 sys-id-ext 10)

             Address     3cdf.1ecc.7980

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

             Aging Time 300

Interface        Role Sts Cost      Prio.Nbr Type

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

Gi0/6            Desg FWD 4         128.6    P2p Peer(STP)

Gi0/7            Desg FWD 4         128.7    P2p Peer(STP)

For your 3560 te 2960s are running PVST+ but they are configured  for RPVST+.

Can you reload them to see if you still have the same behaviour ?

Regards.

Alain

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