Need Redundant uplink in Cisco 3400 from two different Cisco 3750 and Cisco 3560.

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Dear Experts,

I need very Urgent Redundant uplink in Cisco 3400 from two different Cisco 3750 and Cisco 3560.

At present Cisco 3750 is a Main Switch to connect cisco 3560 gi0/1 and Cisco 3400 Gi0/1 as a up link to communication our authentication server.

Cisco 3750 Int gi1/0/1 --••à Cisco 3560 gi0/1

Cisco 3750 int Gi1/0/2 --••à Cisco 3400 gi0/1

I need one more uplink in Cisco 3400 from Cisco 3560 int gi0/2 to Cisco 3400 int gi0/2 when fiber break ( connected with 3750 gi1/0/2 to 3400 gi0/1) it’s automatic working on 3400 gi0/2 from Cisco 3560 gi0/2.

So how can I achieve my requirement without any loop occur

Thanks in ADV,

[andrew.prince]

Just configure the 3750:-

spanning-tree vlan 1-1005 priority 0

and the 3560:-

spanning-tree vlan 1-1005 priority 4096

No loops will ever occur.

[marcinwojcik]

Hi Andrew,

Do you configure the priority just to make sure that the 3750 will be the root?

It would work without setting the priority up but we wouldn't be sure which switch becomes the root - is that correct?

Marcin

[Freihafener]

IIRC that´s right - as long as you have no other switch with prio 0 on the vlans...