Time has passed after setting up Customer-X cross-connect between their two sites – customer is so pleased with the service you have been providing that now they wish to bring in the other 20 sites into a common connectivity solution. You call a meeting to discuss the requirements and the following is agreed:

  • All other sites have a standard internet connection
  • The Internet provider is the same for all sites
  • Currently, inter-site connectivity is achieved via IPSecVPNs
  • IPSec VPNs are causing few performance and stability problems

This scenario is a very good candidate for a MPLS-L2VPN solution – one way of achieving this is by configuring a [tooltip tip=”Virtual Private LAN Service – emulation of a broadcast domain over an MPLS core.”]VPLS[/tooltip].

We have seen that pseudowires allow you to create a 2x ports Virtual Switch across your MPLS core; one site would then connect to each port allowing therefore a point-2-point switched communication between the two sites.

A [tooltip tip=”Virtual Private LAN Service”]VPLS[/tooltip] is an extension to the pseudowire setup whereby, in order to simulate a broadcast domain, a full-mesh topology of pseudowires is created between all PE ports. Furthermore, the full-mesh topology is automatically created and managed by the PE [tooltip tip=”Label Switch Routers”]LSRs[/tooltip]. Imagine creating a full-mesh topology manually for all 20 sites for this customer!?

You can see below a visual comparison between the two:

MPLS-L2VPN-VLL-vs-VPLS-1

Notice that, to illustrate the concept of L2VPN, I have hidden the PE routers – facing the customer, they now became L2 devices while running MPLS on top of OSPF within the provider’s core network. 

Unfortunately, I am not able to simulate this environment in my lab since this is an advanced feature which has not been implemented in dyanamips. I do hope however that it is now clearer to you what a VPLS is and when it should be used.

There is two more MPLS applications I would like to illustrate – these are MPLS-L3VPN and MPLS-TE – so stay tuned!

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Thank you,
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