Vlan tag translation on a Catalyst 3750G

[liotti]

Hi all

I was asked to implement a Vlan tag translation between two ports on a C3750G.

Simply put, I have two trunking interfaces. Traffic coming in from a certain trunking interface, say Gi0/12 tagged with, say, Vlan ID 12 should be forwarded out of another trunking interface, say Gi0/20, but with Vlan ID 20. And the other way around.

Is there a way to accomplish the request other than cross-connecting two access ports in the two Vlans? This works, but seems awful to me and I thought there should be some smarter solution. But I see C3750G lacks the "switchport vlan mapping" command.

Thank you, best regards

Luigi

[marce1000]

 - Looks not available on that platform :

          https://community.cisco.com/t5/switching/catalyst-3750-quot-switchport-vlan-mapping-quot-command-does-not/td-p/2893843

 M.

[liotti]

Yes it's clear and well documented that the "switchport vlan mapping" is not available on this platform.

What I was asking is if there is a smarter and cleaner way to accomplish the requirement than simply connecting the two vlans with a patch cable on the same switch, wasting two ports. Luigi

[balaji.bandi]

Generally, these commands required for the Service provider to that kind of translation.

example like below :

https://www.cisco.com/c/en/us/td/docs/switches/metro/catalyst3750m/software/release/12-2_58_se/configuration/guide/3750metro_scg/swtunnel.html

[liotti]

Hi.

There's no service provider involved in this task. There are only two Ethernet devices with 802.1Q trunking ports, one tagging with tag 12 and the other with tag 20. They should be connected at layer two. The tags on the two devices can not be changed.

Luigi

[balaji.bandi]

what I meant was, those features needed mostly SERVICE PROVIDER METRO Environment if your switch does not have that feature that is the limitation of the device which you purchased, to work your requirement, you need to have right device

or if you have spare l ports you can connect VLAN12 on the side and VLAN 20 other side dedicated port should work technically you need to test it. (make sure no loops in the network).

[liotti]

Hi

Indeed, I did not purchase anything: I was just asked if this can be done, with this switch. I can happily answer "no, this can not be done short of wasting other two ports", but I wanted to be sure and was curious if there could be some better way to do it. "No" is an acceptable answer, just wanted to be sure.

I can confirm that connecting two access ports, one in VLAN 12 and the other in VLAN 20, works. I had to disable cdp to dispose of annoying warnings about the mismatching VLANs. In my scenario there are no loops: there are really only two devices with only 1 port each, but these ports are tagging on different vlans.

Regards

Luigi