loop on CISCO ASA 5505

[Alexandre Letard]

Hello,

I have a problem with the configuration of my Cisco ASA 5505. I have 2 interfaces 0/2 and 0/3 which are each connected to a switch SW1 and SW2.

On these interfaces I have a trunk multiple VLANs. When I plug the interface 0/2 on the SW1 no problem. But when I add the interface 0/3 on SW2, I have a loop that is.

I made a shema to understand.

the 5505 does not support the spanning tree, the spanning tree is configured on two switches.

Is there a solution to activat the interface 0/3 when 0/2 is down ?

Config of  ASA (0/3 is shutdown to avoid the loop) :

interface Ethernet0 / 2

  switchport trunk allowed vlan 2-4

  switchport mode trunk

!

interface Ethernet0 / 3

  switchport trunk allowed vlan 2-4

  switchport mode trunk

  shutdown

!

[cadet alain]

Hi,

you can use the redundant interface feature:

http://www.cisco.com/en/US/docs/security/asa/asa80/configuration/guide/intrface.html#wp1045838

Regards

Alain

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[Alexandre Letard]

thank you, I'll watch.

I found this command that also seems to solve my problem:

switchport protected (on both interfaces)

Not familiar with the operation of this command. I'll try your method which is more understandable.

[cadet alain]

Hi,

switchport protected will prevent interfaces with this feature to communicate, this is also called pvlan edge feature but it will not prevent STP loops to my best knowledge.

Regards

Alain

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[Alexandre Letard]

unfortunately I do not have controls available ...

FW-B1#

FW-B1# conf t

FW-B1(config)# int ?

configure mode commands/options:

  Ethernet  IEEE 802.3

  Vlan      Catalyst Vlans

FW-B1(config)# int

[cadet alain]

Hi,

you can also try this on the switch side:

http://www.the-lan-man.net/wordpress/2010/asa-5505-switch-redundancy/

Regards

Alain

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[Alexandre Letard]

thank you for your help Alain,

unfortunately i don't have a 3750 stack behind but I have only 2 DELL 3524 without stack.

there is just a port-channel between swtichs.

I'll keep looking, but my case seems to have no solution

thank you again