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Community Member

802.1Q tunneling over a legacy switches infrastructure

Hi Experts,

Is it possible to use Catalyst 2950G-24-EI for forwarding 802.1Q Tunneling frames (i.e QinQ) ?

I understand these switches do not support the "Tunnel Port" feature, but as we can modify their system MTU to 1504 they could theorically switch such frames (looking only at the head for destination @MAC, metro tag VLAN Id and tail for checking the FCS)?

My plan is to implement the following network :

CustomerA--(3750----2950---3750)--CustomerA

Service Provider Netw.

Of course, Catalyst 3750 support 802.1Q Tunneling

(http://www.cisco.com/en/US/products/hw/switches/ps5023/products_configuration_guide_chapter09186a00802c1101.html)

Thanks in advance,

Best regards,

Stephane.

2 REPLIES

Re: 802.1Q tunneling over a legacy switches infrastructure

Yes you can very much use the 2950G switch in between as a intermediate Switch between your QinQ HEad and Tail End.

You can simply consider the intermediate switches as P routers in MPLS. The P routers dont know how to process and also dont care what the VPN label is. They only switch/swap based on the outer label, and ignore the inner label.

THe same happens in Metro intermediate devices, the 2950G switch will simply ignore your inner vlan TAG.

HTH-Cheers,

Swaroop

Community Member

Re: 802.1Q tunneling over a legacy switches infrastructure

Thank you for your quick answer (and good news!)

Do you know where I can find a Cisco official document stating this ? I searched the web for hours without success.

This is important as I cannot go any further in this project without Cisco support.

Thanks and best regards,

Stephane.

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