L2TP, Q-in-Q... which provides what I need?

[brianmnagy]

Background:

Have a 10 Mb (7 bonded T1s) point to point circuit currently. Using VLAN tagging, I'm using the same VLANs between the two sites. This works fine, no problems.

New Issue:

Upgrading to a 100 Mb point to point circuit. This new circuit will also allow for VLAN tagging but we are limited to 50 MAC addresses with the carrier. The 10 Mb circuit never had this limitation. What do you recommend as a method to continue using the same VLANs between the two sites but not exceed the 50 MAC limit to the carrier?

From my research I think I need some sort of tunnel. The switching I have in place (HP) doesn't support this. I was thinking I needed to hang Cisco routers off the switching on both sides and do a L2TP tunnel. Would this "hide" the MAC addressing while still allowing me to extend the VLANs between the sites?

[Giuseppe Larosa]

Hello Brian,

yes with L2TPv3  see

http://www.cisco.com/en/US/docs/ios/12_3t/12_3t2/feature/guide/gtl2tpv3.html

But be aware that the performance will be limited by the routers you deploy

802.1QinQ does not provide MAC address hiding so it is not useful in this case.

You need a routed solution to limit the number of MAC addresses seen in the new link so an L2TPv3 tunnel can do the job.

Hope to help

Giuseppe

[brianmnagy]

Giuseppe. I appreciate the guidance. I'll read through that guide and select an appropriately sized router.

My current setup has firewalls on both sides being the gateway (for all VLANs). If I put a router in place with L2TPv3 will that create a transparent link between the sites? Or would I need to change the routes for the VLANs to make the router the default gateway.

I created a quick mock up, wasn't sure if I am being clear.

[Giuseppe Larosa]

Hello Brian,

the routers with L2TPv3 will provide a point to point L2 transport service and will not act as default gateway for served Vlans so my first impression is that you can keep using your current devices ( the firewalls) as L3 gateways for the hosts.

It is just an extension of a L2 trunk over an IP network

Switch-Site1 ---- L2 trunk ---- L2TPv3 router site1 -----  100 Mbps link ----- L2Tpv3 router site2 --L2 trunk- Switch site 2

Hope to help

Giuseppe

[brianmnagy]

Guiseppe,

I see a guide for which router to use on L2TP but not L2TPv3. I was planning on using a 3825 for this 100 Mb connection. What are you thoughts on this choice?

Also, do you know if the protocol is standard or will I need a particular IOS release?