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How do you establish connections across multiple MPLS providers?

Your company is merging: How do you link disparate WAN service providers to ensure continued connectivity?

As enterprises acquire or merge with other companies, it's likely they'll have to reconsider their WAN infrastructure....

Multiprotocol label switching (MPLS) providers are investing heavily to extend their networks. But merged or acquiring enterprises may still have to face the fact they'll be dealing with multiple service providers to handle their MPLS and virtual private LAN service needs.

IT teams can use one of two approaches: a VPN interconnect, aka the "do-it-yourself" (DIY) interconnect or a VPN network-to-network interconnect (NNI).

The DIY interconnect

One of the simplest ways to connect two networks is through an interconnect. In theory it's simple, but the cost and management implications require careful focus. For acquisitions and mergers, the do-it-yourself interconnect is the most common method to join dual providers together.

There are certain aspects of this process you should keep in mind:

  • Support. How the two providers will support the end-to-end technology should be carefully considered. When an issue occurs, each provider will need to be contacted especially if your IT department is unsure where the problem resides. In many cases, an unbiased third party is recommended to oversee and troubleshoot the problem to alleviate any dual supplier relationship tensions that may occur.
  • Interconnect resiliency and diversity. Joining two providers requires the resources of data center to support connectivity. It is important to maintain security from a switched fiber perspective as well as from the actual provider's edge node device.
  • Visibility. Use the border gateway protocol to get the insight required to develop routing information between each service provider entity.

MPLS across multiple providers will undoubtedly create additional traffic latency. That's due to the additional distance, coupled with the additional hardware required to terminate dual providers. In addition, quality of service (QoS) metrics will need to be replicated from both to ensure traffic priority is maintained.

The network-to-network interconnect

The more standard method to connect multiple MPLS providers is through a network-to-network interconnect, where carriers contract a third party to provide telecommunications services in regions where they don't have a presence.

Consider the following issues when dealing with NNIs:

  • Service level agreements (SLAs). Understand how SLAs are met and governed by your providers as well as the NNI carrier. Consider the resiliency of the network-to-network core interconnect together with packet latency.
  • QoS. The NNI should be a transparent component of your overall WAN. So, make sure to review each service provider's company policy for the end-to-end VPN QoS. Any QoS settings should be picked up and honored on an end-to-end traffic basis. Latency and jitter performance should be within limits whenever delay-sensitive application traffic is distributed over the network.

Running MPLS across multiple providers is less than ideal. But by considering the implications of both VPN scenarios discussed above, service performance can be made predictable.

Editor's note: More information about WAN procurement is available through Robert Sturt's TechTarget Mindmap.

Next Steps

Designing a WAN topology

Gauging MPLS performance

This was last published in May 2015

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