MPLS is the typical underlying plumbing for a carrier style network core that can support L3 VPNs, VPLS and various other services, although other "stuff" can be used.
MPLS is the common way to do this and seems to be "best common practice" right now.
The carriers need big, large scale, flexible core networks that can support traffic from lots of customers on a common set of equipment and resilient WAN links, but provide separation between them.
VPLS mainly assumes Ethernet delivery, so can be good where that is available for all your needed locations, but may be limiting.
VPLS emulates a switched Ethernet LAN and as such suffers from the related scaling and diagnostic issues - i would not want to use VPLS to connect more than a few dozen sites in a single network, and you will need routers to control traffic well before that point.
Some other "Ethernet over cloud" type systems give different sets of tradeoffs - Ethernet pseudowire services for example scale better but need more detail design and planning.
L3 VPNs will work with any type of access - conventional 1.5m and 2m links may be all you can get in some places / countries, or you might need VSAT for that location in Africa and so on....
Many carriers have NNI links to others for L3 VPNs, so you can get to places outside their geography. International broadcasters for example may want links to every continent.
L3 is easier to use with QoS, works better with multicast and various others services.
L3 means the carrier(s) are involved in the IP topology, and in turn that may limit what protocols you can use - that may work well for you or just cause more hassle.
None of these issues are black and white, but a specific set of requirements will "push" you towards 1 type of system.
And real life is complicated - you may end up using both for a big network.
Technical jargon aside, I would break down the CIO’s comparison of the two technologies into two main categories:
1) Immediate Impact on the Organization’s Strategy
a. How does each technology meet the organization’s short-term needs/requirements?
b. What value does each technology add to both the organization (and the IT group)?
c. What’s the immediate impact on application performance (i.e. User Experience, etc…)?
d. What’s the immediate impact as it relates to budget?
2) Long-Term support for changes to that Strategy
a. Which solution can easily support business changes?
i. Do both solutions scale geographically?
ii. Can both solutions support ancillary services?
b. Which solution best supports technological changes in the business?
i. Consolidation/Centralization Strategies
ii. Convergence Strategies
iii. Cloud / SaaS Strategies
c. What impact, if any, does either solution have on
i. Long-term revenue generation.…
ii. Long-term cost containment.…
In other words ... do a solid business case analysis. NOT just a technical review. Accomplishing this will also help you when it comes time to "sell it" to senior management.
Courtesy - Broadband Nation
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