Introduction to Differentiated Services (DiffServ) and HP-UX IPQoS

Adapters

Adapter blocks assign policies to specific configured adapters (NICs) on the system.

XYZ Configuration

XYZ has determined that they’ll reserve at least 40% of the bandwidth for VoIP communications. The

remaining bandwidth will be used for all other communication. Using this information, the following

configuration was implemented on their HP-UX systems and similar configurations propagated to their

border routers

# Simple VoIP example configuration

# Define Filters

filter voip_traffic_f

port 7000

protocol udp

priority 1

# Define Policies

policy voip_traffic_p

uses voip_traffic_f

res 40%

dscp 46

# Define Adapters

adapter lan0

uses voip_traffic_p

In the above example, the filter voip_traffic_f identifies all communication received via UDP and port

7000 to apply the forwarding behavior defined in the policy voip_traffic_p. Adapter lan0 has been

identified as the outgoing interface. You’ll note that “policy voip_traffic_p” lists “dscp 46”. The value

“46” denotes that the packets are to receive Expedited Forwarding PHB (see RFC 2598, An

Expedited Forwarding PHB for additional information). All other traffic which has not been defined in

a QoS configuration will receive the Default PHB of Best Effort service subject to defined policies

precedence.

Using DiffServ in their environment now allows XYZ Corporation to receive guaranteed bandwidth for

their VoIP applications, reducing jitter and delays, for uninterrupted communication.

Note that the example is for illustration and that the protocols and port id’s used can vary with different VoIP applications. Check your VoIP

product’s documentation for further information or for other possible classifiers.