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New Member

Possible to extend a VLAN on a 3560 over to a 3550 switch?

Hi, my set up is:

Cisco ASA > 3750 switch attached as a trunk to the ASA > off the 3750 switch I have a 3560 switch too as a trunk.

The 3750 has many VLAN's

The 3560 has one single VLAN (VLAN 6)with only one free port.

I have a spare 3550 switch and I wondered if I can simply extend the VLAN 6 on my 3560 across to my 3550 switch to give more ports?

Thanks

6 REPLIES
New Member

Re: Possible to extend a VLAN on a 3560 over to a 3550 switch?

Sure, you can do that easily, and several ways.

1. Just put the last remaining port on the 3560 in VLAN 6, in access mode, and plug the spare 3550 in to that port. The 3550 unconfigured will be entirely in VLAN 6.

2. Trunk the last port in the 3560 to the spare 3550, and then put all the remaining ports in VLAN 6 on the 3550 (if you don't use VTP, you will have to manually create VLAN 6 on the spare 3550, but putting any ports on the switch IN to VLAN 6 will create it for you.)

3. Use VTP on ALL of the switches, and connect the spare 3550 to the 3560 (trunk the link between them) and then VTP will propogate ALL the VLANS to all the switches, and you can put the spare 3550's ports in to VLAN 6 then.

HTH

New Member

Re: Possible to extend a VLAN on a 3560 over to a 3550 switch?

Great!

Option 1 and 2 sound good. Especially 2.

What trunk info would I need to add to both switches?

Thanks

New Member

Re: Possible to extend a VLAN on a 3560 over to a 3550 switch?

It depends on your preference. To hard-set both interfaces to trunk, you would simply need to add

"switchport mode trunk"

to both;

then just make sure the encapsulation matches on both

"switchport trunk encapsulation "

I use dot1q since it is a standard, and ISL is proprietary and I believe it is going away?

That should do it, unless you have some VTP settings configured, the domain should match on both switches.

New Member

Re: Possible to extend a VLAN on a 3560 over to a 3550 switch?

Thanks, is this right.

On the 3560 that is full (I need to extend VLAN 6) I have port 2 free.

So does this look right:

Interface Gigabitethernet0/2

Description trunk to 3550

switchport trunk encapsulation dot1q

switchport mode trunk

Put a Cat5e cable into port 2 of the 3560 and port 1 of the 3550.

On the 3550:

Make all ports switchport access vlan 6

Interface FastEthernet0/1

Description Trunk to 3650

switchport trunk encapsulation dot1q

switchport mode trunk

plus:

Do I have to add switchport trunk allowed vlan 6 anywhere?

New Member

Re: Possible to extend a VLAN on a 3560 over to a 3550 switch?

You shouldn't need to add the VLAN allowed bit, unless it is already in the switch, then you should add VLAN 6 to that statement.

New Member

Re: Possible to extend a VLAN on a 3560 over to a 3550 switch?

So does this look right:

Interface Gigabitethernet0/2

Description trunk to 3550

switchport trunk encapsulation dot1q

switchport mode trunk

Put a Cat5e cable into port 2 of the 3560 and port 1 of the 3550.

On the 3550:

Make all ports switchport access vlan 6

Interface FastEthernet0/1

Description Trunk to 3650

switchport trunk encapsulation dot1q

switchport mode trunk

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