Monday, November 10, 2008

When Is VPLS Deployment The Better Choice For Global Connectivity?

When should you choose VPLS (Virtual Private LAN Service) as the WAN technology for your enterprise-wide global connectivity ... as opposed to say Layer 3 MPLS VPNs?

Simply put .... the main reasons I hear most businesses say they chose VPLS over a Layer 3 (laymen term "MPLS") is:

1. They can control their own routing (this is the biggie)

2. It's inherently more secure (because they don't advertise routes to carrier)

3. If the client is already running a dynamic routing protocol such as EIGRP or OSPF, the migration is much easier that going to a layer 3 solution

4. Easier migration from point to point or frame relay network

To be more specific ..... one of the largest reasons for the choice of VPLS vs a layer 3 MPLS service is the ability to control one's own routing. In close second is the ability to select one's routing protocol of choice vs having to rely on the select set most service providers are able to support on their layer 3 MPLS offerings (e.g. OSPF, RIPv2, BGP, etc).

One interesting topic which keeps coming up is how an enterprise can scale a VPLS service globally without routing. There are some customers who are keenly interested in enabling a global switched any to any infrastructure, with the only traffic the Service PRovider seeing at layer 2. All routing is typically handled via separate hardware in these types of designs. There's a great white paper on the subject at VPLS Decisions which explains in detail scaling of VPLS in large networks up to or over 1,000 locations.

From my standpoint, I put it more simply, it's a question of hardware and trust:

1. Do you want the service provider participating in your routing? Can you run or transition to a routing protocol they can support?

2) Does your own infrastructure have the ability to fully route it's own environment or is a shared Layer 3 routed infrastructure better for you given the reductions in processing power it can require?

Consider also what you'll use as a network backbone. It's likely that the backbone will be based off of a DS3 bandwidth network. However, you may scale up to OC3 bandwidth ... or scale down to a series of T1 bandwidth circuits.

There's much to think about if you are considering global connectivity of a network. For free assistance I suggest using the no cost services available at Bandwidth Solution


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