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Diffserv (differentiated services) and MPLS
(Multiprotocol Label Switching) are two separate standards which
purport to help solve the IP quality problem. Diffserv takes
the IP TOS (type of service) field, renames it the DS byte,
and uses it to carry information about IP packet service requirements.
It operates at Layer 3 only and does not deal with lower layers.
On the other hand, MPLS specifies ways that Layer 3 traffic
can be mapped to connection-oriented Layer 2 transports like
ATM and Frame Relay. MPLS adds a label containing specific routing
information to each IP packet and allows routers to assign explicit
paths to various classes of traffic. It also offers traffic
engineering and techniquest that can boost IP routing efficiency.
So what does this all mean in terms of costs
and compatibility? Diffserv relies on traffic conditioners sitting
at the edge of the network to indicate each packet's requirements.
While MPLS requires investment in a network of sophisticated
label-switchin routers capable of reading header information
and assigning packets to specific paths like virtual circuits
on a switched network.
This is an abstract of the article "Diffserv
and MPLS: A Quality Choice" November 21, 1998, Data Communications.
See the full article for a detailed description of Diffserv.
View more information in protocols.com about
MPLS.
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