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Network Convergence IP/MPLS

In April 2005, the ATM Forum merged with the Frame Relay Forum and the MPLS Forum to form the the IP/MPLS Forum. The aim of this new Forum was converging the implementation of multi service packet technologies in the global networking communications industry by driving “ the global adoption of IP/MPLS-based technology, networks, services and solutions."
IP is network layer protocol over Ethernet /ATM/SONET/SDH/etc. Although IP has many advantages, it also has a few problems:

Lacked fast routing - routing at the IP level is complicated and slow for backbone routing that utilise fast switching protocols such as ATM or another layer 2 switching protocol.
Connection to ATM networks - ATM and IP integration solutions usually have an overhead of routing. IP is not designed for cell switching.
Lack of an integrated solution for quality of service and class of service handling – IP handles all traffic equally, but in real life, priority handling to support QoS for certain services is essential.

This lead ISPs to swap IP networks for ATM networks.

MPLS

MPLS [Multi Protocol Label Switching] solves the problems with IP networks and enables further services such as traffic engineering.

MPLS resides in the gap between the network layer and data link layer [layers 3 & 2 in the OSI model], adding a label [32 bits] of data, to support all these services. It allows:

Fast switching [only 32 bit processing
Multiple protocols to interconnect [the labels are the same for all protocols].
Traffic engineering - building label-unique routes, each with a different class of service and a different quality of service.

MPLS does not replace IP, it enhances it by providing an improved interface to data link switching fabrics and optical networks than defined over ATM.

More on MPLS

Today networks need to support high volumes of best effort data using file transfers, electronic mail, and Internet access.

Different classes of traffic c require different Quality of Service [QoS] - data, voice, and video. This QoS differentiation relies on the capabilities of the underlying network elements - the routers and switches that implement the protocols.

Traditional hop-by-hop processing at its technological limit did not support this requirement, thus a conceptual shift in the forwarding process was required.

By evolving the IP network architecture to prepare next generation networks, allows a smooth and cost controlled transition from the current environment.

Todays networks need to support:

Different classes of traffic with specific service characteristics guaranteed across the complete path through the network [and often across multiple autonomous systems].
Carrier-class, multi-customer IP infrastructures require robust networks that can manage resources more effectively.
Traffic Engineering

And, this means:

Bigger, faster, cheaper routers
Multilayer switching technology

Next: Benefits of IP Layering