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DiffServ-Aware Traffic Engineering Features
DiffServ-aware traffic engineering provides the
following features:
- Traffic engineering at a per-class level rather than at
an aggregate level
- Different bandwidth constraints for different class types
(traffic classes)
- Different queuing behaviors per class, allowing the router
to forward traffic based on the class type
In comparison, standard traffic engineering does
not consider CoS, and it completes its work on an aggregate basis
across all Differentiated Service classes.
DiffServ-aware traffic engineering provides the
following advantages:
- Traffic engineering can be performed on a specific class
type instead of at the aggregate level.
- Bandwidth constraints can be enforced on each specific
class type.
- It forwards traffic based on the EXP bits.
This makes it possible to guarantee service and
bandwidth across an MPLS network. With DiffServ-aware traffic engineering,
among other services, you can provide ATM circuit emulation, VoIP,
and a guaranteed bandwidth service.
The following describes how the IGP, Constrained
Shortest Path First (CSPF), and Resource Reservation Protocol (RSVP)
participate in DiffServ-aware traffic engineering:
- The IGP can advertise the unreserved bandwidth for each
traffic engineering class to the other members of the differentiated
services domain. The traffic engineering database (TED) stores this
information.
- A CSPF calculation is performed considering the bandwidth
constraints for each class type. If all the constraints are met, the
CSPF calculation is considered successful.
- When RSVP signals an LSP, it requests bandwidth for specified
class types.
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