VLAN translation from LAN to WAN

[hostettle]

Hi,

It's a theoritical question.

Suppose a CE with a L2 switch (a client switch at the border of the client site, with WAN interfaces). Is it possible to modify in the L2 switch the VLAN number to go from LAN to WAN, without to crossing through a router. For example, translation of VLAN #10 to VLAN (that is C-VLAN) #200.

It's not in relation with S-VLAN or B-VLAN aggregation.

The VLAN numbers are managed in LAN by the client, and the VLAN numbers in WAN depend on the the possibilities of the provider. So, sometimes, the CE has to change the values, 1 to 1 (after to chck the validity of these).

It would be great if you have a reference.

Best regards,

Michel

[Somasundaram Jayaraman · Accepted solution]

Hi,

I believe your requirement is to extend the vlans from site A to site B through service provider.

In this case, service provider has to perform dot1q tunnel configuration at his end.

++ The concept of dot1q tunnel is to tag the frames with a metro tag which is of four bytes. This tag will be added

by the service provider.

Service provider cannot carry all the vlan traffic in your network between site A and B.

++ So they will add an additional tag which will contain a vlan no, and they will allow only this vlan across the network.

++ service provider needs to make sure the system mtu to be 1504 bytes, since there is a addition of metro tag to the normal packet.

The below link might interest you.

http://www.cisco.com/en/US/docs/switches/lan/catalyst6500/ios/12.2SXF/native/configuration/guide/dot1qtnl.html

If you want to configure etherchannel over dot1q tunnel then 12pt should be configured since control packets will not

be passed in the dot1q tunnel.

Hope this helps

Cheers

Somu

Rate helpful posts

[hostettle]

Hi Somasundaram,

Thanks for your reply... but the question is not solved...

> I believe your requirement is to extend the vlans from site A to site B through service provider.

Yes, you're right.

> In this case, service provider has to perform dot1q tunnel configuration at his end.

Before adding a S-TAG, the provider has to analyse the C-VLAN to get a corresponding S-VLAN in a provider equipment, as NTU for example.

But, in the access, the NTU has to receive from different clients, different C-VLAN. So, sometimes, the client need to translate its own VLAN in good C-VLAN (before tunnel as you said).

> Service provider cannot carry all the vlan traffic in your network between site A and B.

You're right. But, before adding S-VLAN, I-SID, the C-VLAN need to be correct when there is multiplexing in the access.

> ...1504 bytes

1982 bytes, according to 802.3-2008.

Best regards,

Michel

[hostettle]

Hi,

It's a problem of VLAN tag translation or swapping. Is there any LAN switch which can do that?

Best regards,

Michel

[hostettle]

Hi,

I just found the "VLAN translation" function in EX3200 and EX4200 switches from Juniper.

Perhaps it doesn't exist for Cisco.

Best regards,

Michel