Example Traffic Class Configuration for Differentiated Services

The commands in this example illustrate a partial network configuration that supports four differentiated service classes on a particular tunnel: a best-effort class, two assured forwarding classes, and an expedited forwarding class. Table 31 presents the mapping between EXP bits, PHB, PHB ID, and traffic class/color combination.

Table 31: Differentiated Services Mapping

Note: This example includes both MPLS and policy configuration commands, and assumes that you are thoroughly familiar with the information and commands presented in the JUNOSe Policy Management Configuration Guide.

The four traffic classes are configured to allocate fabric resources and allow global synchronization of the three segments of the data path through an E Series router: ingress, fabric, and egress. The JUNOSe software automatically creates the best-effort traffic class, with a default weight of eight. You must define the remaining three classes, af1, af2, and ef. In this example, the af1 class has twice as much fabric bandwidth as the best-effort class, and the af2 class has twice as much fabric bandwidth as the af1 class. The expedited forwarding traffic (the ef class) requires strict-priority queuing.

Define two scheduler profiles for the af1 and af2 classes on the egress line modules:

Create queue profiles to define how queues are instantiated to implement the corresponding traffic classes and PHBs. The JUNOSe software automatically creates the best-effort queue profiles.

The scheduler and queue profiles are referenced in QoS profiles. For example, you can create a QoS profile for port-based per-class queuing or for LSP-level per-class queuing (configuration omitted).

You must map the PHB IDs to the appropriate traffic class/color combinations:

Configuration on the Ingress Router

You must access the tunnel interface to map the PHB IDs to the EXP bits. The E Series router signals this mapping to all routers on the tunnel. You can establish different PHB-ID–to–EXP mappings for different tunnels.

PHB-ID–to–EXP mapping for the best-effort traffic class:

PHB-ID–to–EXP mapping for the af1 traffic class:

PHB-ID–to–EXP mapping for the af2 traffic class:

PHB-ID–to–EXP mapping for the ef traffic class:

Define classifier control lists to classify the incoming packets into classifier groups. Although not shown here, for each CLACL you must define the rules that will select the appropriate incoming packets: be, af1, af2, or ef.

Define a policy that maps the selected packets into traffic classes. For the assured forwarding classes, this example uses rate limit profiles to set the colors.

You attach the policy to the ingress interface of the ingress router. As packets arrive, they are classified with the internal traffic class/color combination and forwarded into the appropriate queues in the fabric. When the packets are sent into the tunnel out of the ingress router, the EXP bits are set according to the router-generated policy (in this example called mpls-exp-setting) that the JUNOSe software automatically attached to the tunnel.

Configuration on the Ingress and Transit Routers

When the tunnel is established, the JUNOSe software automatically creates an output policy to map traffic-class/color combinations to EXP bits and attaches the policy to the outgoing segment of the tunnel. The JUNOSe software generates classifier list and policy list names, and creates the EXP-setting policy as if the following commands were entered:

Note: You do not actually issue these commands; they represent the behavior automatically performed by the router.

Note: For a topology-driven LSP, you have to configure and apply the classifier list and policy list manually.

Configuration on the Transit and Egress Routers

When the tunnel is established, the JUNOSe software automatically creates an input policy to match the EXP bits and map them to the traffic-class/color combinations and attaches the policy to the incoming segment of the tunnel. The JUNOSe software generates classifier list and policy list names, and creates the policy as if the following commands were entered:

Note: You do not actually issue these commands; they represent the behavior automatically performed by the router.

Note: For a topology-driven LSP, you must configure and apply the classifier list and policy list manually.

The packets are forwarded to the appropriate fabric queue according to the traffic class/color combination. On a transit router, when the packet is forwarded out of the tunnel, the router-generated output policy then sets the EXP bits back according to the traffic class/color combination. Typically, the effect of the EXP bits to traffic class/color combination to EXP bits is no change.

On an egress router, where the tunnel terminates, no router-generated output policy is attached, and the packets pass out of the router subject to any manually configured IP policy management applied to their traffic class/color combination.

Related Topics

• See the JUNOSe Policy Management Configuration Guide for more information about defining policies.
• Configuring MPLS and Differentiated Services
• Configuring EXP Bits for Differentiated Services
• Example Differentiated Services Application and Configuration
• Classifying Traffic for Differentiated Services
• mark-exp
• mpls classifier-list
• mpls diff-serv phb-id traffic-class
• mpls match exp-bits
• mpls match traffic-class
• mpls policy-list
• mpls policy-statistics
• mpls traffic-class
• tunnel mpls diff-serv phb-id

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