cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
1804
Views
0
Helpful
3
Replies

VLAN span across WAN

siddhartham
Enthusiast
Enthusiast

I already saw many posts about this topic but didn't get a clear idea.

We have a pair 2951 s, one at HQ and the other one at DR, connected through a DS3 (MPLS (L3-VPN)) Link. We want to span VLANS between the two data centers over the existing MPLS. Is L2TPv3 is a good solution in this case? Accrodin to the foloowing cisco document (

http://www.cisco.com/en/US/products/ps6587/products_white_paper09186a00800a8444.shtml) its only supported on 12000,10720,7200 and 7500 platforms. If we want to acheive the goal with 2951s, can we use bridging between the routers ?, if yes can we span the VLANs selectively.

If we span the VLANs will a loop (broadcast strom) at one place affects the other place? how does the spanning tree work in this case?

We are planning to get a 500 Mbps point to point Ethernet connection between HQ and DR. Can we just put 2 switches on either side and configure them as trunk ports and Span the VLANs across the 2 sites? Do we have to give any special instructions to the service provider in this case?

What happens in the below scenario

We have 2 links between HQ and DR, one is a MPLS circuit and the other one is a Ethernet Point to Point. If we create a L2TPv3 tunnel over MPLS and configure the point to point link as a trunk and span VLANS over both the links, will it fom a loop? How does the STP work in this scenario.

Thanks for your help!

Siddhartha       

Siddhartha
1 Accepted Solution

Accepted Solutions

Edison Ortiz
Hall of Fame Mentor Hall of Fame Mentor
Hall of Fame Mentor

What's the reason for spanning vlans over the WAN?

The ISR G2 will support L2TPv3 services.

The loop prevention will be handled by STP. The router simply provides the 'pseudowire'.

The devices attached to the router will see each other as directly connected.

If you have multiple links between sites and plan on having 'L2 extended',

you need to address it as if they were inter-connected in a wiring closet.

Also, keep in mind, the connection will rely on its slowest link.

Based on your posting, the WAN is a 500Mbps link.

If you have local 1Gbps uplinks, the 500Mbps link is your bottleneck..

View solution in original post

3 Replies 3

Edison Ortiz
Hall of Fame Mentor Hall of Fame Mentor
Hall of Fame Mentor

What's the reason for spanning vlans over the WAN?

The ISR G2 will support L2TPv3 services.

The loop prevention will be handled by STP. The router simply provides the 'pseudowire'.

The devices attached to the router will see each other as directly connected.

If you have multiple links between sites and plan on having 'L2 extended',

you need to address it as if they were inter-connected in a wiring closet.

Also, keep in mind, the connection will rely on its slowest link.

Based on your posting, the WAN is a 500Mbps link.

If you have local 1Gbps uplinks, the 500Mbps link is your bottleneck..

Thanks for your response Edison, Can we use bridging (irb)  or DLSW+ in this scenario? We have some IBM applications, Vmotion and Exchange serivces that reuire VLAN spanning between HQ and DR.

Siddhartha

Siddhartha

You could but L2TPv3 is more straightforward and less router intensive.

It also takes the router out of the L2 domain.

Getting Started

Find answers to your questions by entering keywords or phrases in the Search bar above. New here? Use these resources to familiarize yourself with the community:

Recognize Your Peers