Cisco 10000 Series User Manual

20-26
Cisco 10000 Series Router Quality of Service Configuration Guide
OL-7433-09
Chapter 20 Configuring Quality of Service for MPLS Traffic
MPLS Traffic Engineering—DiffServ Aware
If you only want to provide bandwidth guarantees, use the DiffServ assured forwarding queue (AF
PHB). On the Cisco
10000 series router, use one of the existing class-based weighted fair queuing
(CBWFQ) queues.
2. Ensure that the router places the guaranteed traffic from the sub-pool tunnel in the guaranteed
bandwidth queue at the outbound interface of every tunnel hop, and that the router does not place
any other traffic in this queue. To do this, mark the traffic entering the tunnel with a unique value in
the MPLS EXP field. The router sends only the marked traffic into the guaranteed bandwidth queue.
3. Ensure that the router does not oversubscribe the queue and instead sends only the amount of traffic
into the sub-pool tunnel that the guaranteed bandwidth queue can handle. To do this, limit the rate
of the guaranteed traffic before it enters the sub-pool tunnel. The aggregate rate of all traffic entering
the sub-pool tunnel is less than or equal to the bandwidth capacity of the sub-pool tunnel. For delay
or jitter guarantees, excess traffic is dropped. For bandwidth guarantees, excess traffic can be
marked differently for preferential discard.
4. Ensure that the amount of traffic entering the guaranteed bandwidth queue is limited to an
appropriate percentage of the total bandwidth of the corresponding outbound link. The exact
percentage to use depends on several factors that can contribute to accumulated delay in your
network: your QoS performance objective, the total number of tunnel hops, the number of links
folded in along the tunnel path, the burstiness of the input traffic and so on. To do this, set the
sub-pool bandwidth of each outbound link to the appropriate percentage of the total link bandwidth
by adjusting the sub-pool kbps parameter of the ip
rsvp bandwidth command.
Providing Differentiated Service Using DS-TE Global Pool Tunnels
To provide differentiated service using DS-TE global pool tunnels, do the following:
1. Select a separate queue for each traffic class.
2. Mark each class of traffic using a unique value in the MPLS EXP field.
3. Ensure that packets marked for a specific traffic class are placed in the queue for that class. The
tunnel bandwidth is set based on the expected aggregate traffic across all classes of service.
To control the amount of DiffServ tunnel traffic you intend to support on a given link, adjust the size of
the global pool on that link.
Providing Strict Guarantees and Differentiated Service in the Same Network
Because DS-TE allows simultaneous constraint-based routing of sub-pool and global pool tunnels, you
can provide strict guarantees and differentiated services (DiffServ) simultaneously in a given network.
Verifying and Monitoring DS-TE Configurations
To verify and monitor DS-TE configurations, enter any of the following commands in privileged EXEC
mode:

Cisco 10000 Series Specifications

General

Brand	Cisco
Model	10000 Series
Category	Network Router
Language	English