MPLS and GMPLS are particularly well suited to layer services over a mix of transports,
and to combine multiple services over a common transport, while providing appropriate QoS
for each service.
Carrier Ethernet is a service whereby customers' Ethernet traffic is carried
over a service provider's (carrier's) network. And to build such a service,
a service provider must construct (at a minimum) two network layers.
- They must provide an Ethernet layer that runs transparently from customer premise
to customer premise. The Metro Ethernet Forum (MEF) specifications enable service providers
to provide this layer in a standardized way. The MEF specifies various topologies
for the service including point-to-point (E-LINE) and multipoint (E-LAN and E-TREE).
- They must also implement a transport layer over which Ethernet is carried.
This is private to the service provider and is not standardized by the MEF, but it is
an essential component of providing a Carrier Ethernet service. It must carry
the Ethernet layer in such a way that the MEF specifications are honored.
IP/MPLS networks are an excellent solution to the transport layer requirement.
MPLS pseudowires are used to carry Ethernet traffic between the points of entry and exit
to the Carrier Ethernet service – which are typically at the service provider's
Provider Edge (PE) devices. Pseudowires are flexible, being able to carry almost
any kind of traffic, such as Ethernet frames, ATM cells, Frame Relay, TDM circuits etc.
Typically different traffic sources and types are segregated into different pseudowires,
which can then be managed with a QoS that is appropriate for that traffic source/type.
The pseudowires are set up using MPLS label switched paths (LSPs) inside an outer MPLS
"tunnel", and can support both point-to-point (Virtual Private Wire Service - VPWS)
and multipoint (Virtual Private LAN service - VPLS) service.
For the most sophisticated case (VPLS), a mesh of pseudowires between the relevant PE devices
is established and Layer 2 switching is used to inject traffic into the correct pseudowire.
DC-MPLS provides full pseudowire, VPWS and VPLS signaling support using DC-LDP,
which includes a comprehensive implementation of LDP and its VPLS extensions,
including RFC 4762. DC-MPLS can also be used to signal the underlying tunnels using
DC-LDP or DC-RSVP.
MPLS and GMPLS networks are scalable and dynamic, provide granular QoS,
and can be traffic engineered to maximize use of service provider infrastructure
while maintaining customer SLAs. They can also be set up to provide protection and restoration,
to provide resiliency in the case of link or network failure.
Carrier Ethernet is a very attractive service to service providers - and to their customers.
And MPLS provides an excellent solution to the Carrier Ethernet requirement.
For inquiries about Metaswitch's
MPLS products and expertise contact