Ethernet WAN

Unanswered Question
Jul 17th, 2008

Hi All,

I wonder anyone have extend mutiple vlans over ethernet WAN. Please share your experience. I would want to consider implement trunking vlans over ethernet WAN between two office if it is feasible.

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Overall Rating: 4 (1 ratings)
Jerry Ye Thu, 07/17/2008 - 19:11

Why would you want to trunk your vlan over the WAN. Extending the vlan's over the WAN means you will allow broadcast traffic over your WAN.

Is there any specific benefits you are looking for?



jasonkwang Thu, 07/17/2008 - 19:37

Hi Jeye,

You are right! This is our temporary solution ! The reason is that we would like to relocate some of the servers over to the new office, but at the same time be accessible from both office.

What I do want to know, is it is possible to implement this technically, am I right ? I mean by subscribing etherWAN circuit from my local ISP and configure both my edge switches @ the 2 office, which in my case is two Catalyst 3750G. I do not wish to pay to use any of ISP metro ethernet service.

Jerry Ye Thu, 07/17/2008 - 19:43

Unfortunily, I am not familar with the etherWAN service from your ISP. Maybe you can ask them do they support 802.1q over their WAN.



bauti1428 Thu, 07/17/2008 - 19:44

We have ethernet WAN and they are routed. How can you relocated a server to the other office and at the same time its accessible? :-). I would probably follow a downtime procedure for this if you have one. If this is a temporary solution, eitherway you will need to bring it down to change it again.

jasonkwang Fri, 07/18/2008 - 06:30

Hi, you are right. I guess the reason my client want to do this is they have many server in this particular vlan, and they want to do the relocation at stages instead od one at a go.

Kevin Brennan Fri, 07/18/2008 - 01:36


I have this up an running at the moment between my production and DR sites. I have two small subnets /26 (and 2 VlANS for them) to cut down on the broadcast traffic. The switches on both sides are 6500 series. I use this for VMWare stuff mainly as I have another link to the DR site that I route traffic over.

The service I have from my telco is 100Mb EoSDH. All I did was configure the ports on both switches as trunks and allow the two vlans across them. CDP even works across the link.

Hope this helps


jasonkwang Fri, 07/18/2008 - 06:39

Hi All,

I just found out they are looking at 30MB etherWAN. I will connect my switch port to a fiber converter that terminate to the 30MB etherWAN link. Will I am not too sure whether this fiber converter has a 10/100 ethernet ?

bauti1428 Fri, 07/18/2008 - 06:55

You can actually use your 3750G fiber ports if you have gbic module.

Edison Ortiz Fri, 07/18/2008 - 06:56

I agree with Jerry, extending your Layer2 topology over the WAN is just a bad design.

However, if that's your requirement, then you should look into L2TPv3. More information can be found at:

Or better yet, change your service to Metro-Ethernet and you will have native Layer2 from end-to-end.





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