MPLS is called multiprotocol because it works with the Internet IP, ATM, and frame relay network protocols. With reference to the OSI model, MPLS allows most packets to be forwarded at the layer 2 (switching) level rather than at the layer 3 (routing) level. In addition to moving traffic faster overall, MPLS makes it easy to manage a network for quality of service (QoS).
A Label Switch Path (LSP) can be established in MPLS that crosses multiple Layer 2 transports like ATM, Frame Relay or Ethernet. Thus, one of the true promises of MPLS is the ability to create end-to-end circuits, with specific performance characteristics, across any type of transport medium, eliminating the need for overlay networks or Layer 2 only control mechanisms.
IPLC basically uses Layer 3 (Routing) to build a path for the data to flow in the network. Data routing in an IPLC is done using complex route lookups based on the destination IP address. The routing hardware finds the shortest path between the source and destination IP addresses to send data. This can be a hardware intensive task in times of heavy traffic leading to slower data traffic speeds. With hardware becoming more powerful every day, this is not such a major issue.
However, IPLC has major drawbacks in situations where traffic engineering and setting performance characteristics for different classes of traffic are required. Factors like delay and jitter also come into the picture in an IPLC connection that can cause major drops in QoS levels. This can cause problems in networks where data like video-conferencing are used.
MPLS has an edge over IPLC on this front since it provides network administrators the ability to set the path traffic will take through the network, and set performance characteristics for a class of traffic.
If your network requirements are such that you only need point-to-point connectivity, an IPLC typically will cost less than an MPLS circuit. Since an IPLC is your own private circuit, you can use your managed switches to prioritize traffic. But if you have any near future to add a third node to this network, MPLS will be the best way to go
MPLS could provide at least 2 types of link for this.
a) You can have a layer 2 MPLS (which sort of pretends to be an Ethernet WAN link of various flavours).
this type of service normally needs Ethernet access at each site -so you can connect directly to your LAN switches (but you shouldstill route over the WAN to control what is going on).
Or go for a L3 service - tends to cost more, but more flexible, and likely to allow other services if you want them.
Then you have to decide whether you run the CE routers on the service, or get that bundled, or hook direct to your WAN switches.
Then decide what QoS you want if any, what speed access tails and what type of connections, then possibly how much bandwidth to be rate limited.
The flip side with MPLS is someone else is looking after it for you, and you can add more sites since you have connected to a "cloud" service.