Mpls Qos - Cisco 10000 Series Configuration Manual

Configuring Quality of Service for MPLS Traffic
Multiprotocol label switching (MPLS) combines the performance and capabilities of Layer 2 (data link
layer) switching with the proven scalability of Layer 3 (network layer) routing. MPLS enables you, as
service providers, to meet the challenges of the explosive growth in network utilization while providing
the opportunity to differentiate services without sacrificing the existing network infrastructure. You can
employ the flexible MPLS architecture in any combination of Layer 2 technologies.
The Cisco 10000 series router offers MPLS support for all Layer 3 protocols.
This chapter describes QoS for MPLS-enabled networks and includes the following topics:
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MPLS QoS

Multiprotocol Label Switching (MPLS) quality of service (QoS) allows you, as the service provider, to
provide varying levels of QoS services for different types of traffic in an MPLS network. MPLS allows
you to "tunnel" the QoS of a packet. You can classify packets according to their type, input interface,
and other factors without changing the IP precedence or DSCP field of the packet.
The IP precedence and DSCP fields allow you to specify the QoS for an IP packet. The MPLS
experimental (EXP) field, consisting of 3 bits in the IP header, allows you to specify the QoS for an
MPLS packet. The EXP field is used to support differentiated services and can carry all of the
information encoded in the IP precedence or DSCP field. In some cases, the EXP bits are used
exclusively to encode the drop precedence within a traffic class.
The router applies QoS services based on the class of service (CoS) set for a packet. If the IP precedence
field specifies the CoS, the router treats the packet based on the IP precedence marking. In an MPLS
network, the router copies the IP precedence bits into the MPLS EXP field at the edge of the network.
However, based on the service offering, you might need to set the MPLS EXP field to a value that is
different from the IP precedence value. In this case, MPLS QoS allows the IP precedence or DSCP
setting of a packet to remain unmodified as the packet passes through the provider network. During
congestion, packets receive the appropriate priority, based on the MPLS EXP setting.
OL-7433-09
MPLS QoS, page 20-1
MPLS CoS Multi-VC Mode, page 20-12
MPLS Traffic Engineering—DiffServ Aware, page 20-18
Per VRF AAA, page 20-32
Related Documentation, page 20-32
C H A P T E R
Cisco 10000 Series Router Quality of Service Configuration Guide
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