Trunking with Cisco 4506 n 3Com 2848-SFP switches

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Apr 23rd, 2007
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I have a Cisco 4506 for my core doing Layer 3 routing. I want to trunk ports from the Cisco to the 3Com's for high bandwidth , ie - bonding 2 Gigabit ports together on each switch. Is that possible?? Tks.

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Overall Rating: 5 (1 ratings)
Amit Singh Mon, 04/23/2007 - 08:41
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Yes, that's possible. First create a trunk port on the 4500 switch and change the native vlan to some unused vlan. Cisco trunk port uses native vlan as Vlan1 by default which is not used in the 3Com switches. Do this on Cat4500

Conf t

int gig x/y

switchport trunk encapsulation dot1q

switchport mode trunk

switchport trunk allowed vlan

switchport native vlan 999 <-- this vlan is some unsed vlan on Cat4500.

On 3Com switch, you have to manually tag all the vlans that you want to pass between the two switches.Use the allowed vlan list as mentioned above to allow specific vlan to travel across the trunk port. Also make sure that you are running the required STP mode between the switch i.e make sure that you are running PVST+ atleast on cat4500.

HTH,Please rate if it does

-amit singh


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