Hello Pramod,

you can find how to configure traffic parameters for PVCs and ATM SVCs in the following document.

http://www.cisco.com/en/US/docs/ios/12_1/wan/configuration/guide/wcdatm.html

from

http://en.wikipedia.org/wiki/Traffic_contract

When a connection is requested by an application, the application indicates to the network[2]:

* The Type of Service required

* The Traffic Parameters of each data flow in both directions

* The Quality of Service (QoS) Parameters requested in each direction

These parameters form the traffic descriptor for the connection.

see in the Cisco documents how to configure the various components of traffic descriptor.

Hope to help

Giuseppe