WAN Design Takes an Applications-Focused Approach

By Khali Henderson Comments
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Khali HendersonBusinesses' increasing reliance on hosted and cloud-based applications is making choosing the right WAN technology even more critical. Channel partners, then must resist the temptation to simply respond to a typical request for quote for an IP MPLS VPN with just a price. Specific customer applications and quality of service requirements may call for a different WAN technology like Ethernet, VPLS or even a hybrid approach.

Giving the customer what they want can backfire as one agent discovered the hard way. On the customer's request, his company quoted and subsequently won a $30,000 a month deal for a multisite international IP MPLS-based WAN. Not long after, the client began having issues with its ERP system; specifically, it was timing out during the data replication process between two sites. The agent and its carrier sales engineers resolved the issue with an Ethernet private line between the two sites. However, the agent said the incident gave his company a black eye, which could have been avoided if its sales team was armed with more information about the customer's applications and their use.

"The real debate that's going on is how do you know when you need Layer 3 MPLS or Layer 2 VPLS," said Ray Watson, director of sales engineering for Masergy Communications Inc. "You don't make decisions about Layer 2 or Layer 3 or even Layer 1 based on Layers 2, 3 or 1, but based on Layer 7. It has to be based on what the application is."

Watson is referring to the Open Systems Interconnect (OSI) model, which has seven layers, starting with Layer 1, which describes the physical layer and ascending to Layer 7, or the applications layer. Layer 2, where Ethernet falls, is the data link layer, which provides error-free transfer of data frames from one node to another over the physical layer. Layer 3 is the network layer, which  controls the operation of the subnet, deciding which physical path the data should take based on network conditions, priority of service and other factors. Layer 3 is the known as the IP layer. Technically, MPLS, or multiprotocol label switching, operates essentially in between Layers 2 and 3 and can overlay existing technologies such as ATM or Frame Relay, or operate in an entirely IP native environment. That said, most references to "MPLS networks" assume an IP-based MPLS VPN.

Assess Customer Applications

Watson advises channel partners to get their customers thinking in terms of Layer 7 applications in order to make a recommendation for a WAN design.

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