Title page for ETD etd-08312002-184341

Type of Document

Master's Thesis

Author

Khan, Khurram Matin,

URN

etd-08312002-184341

Title

COPS Usage for Managing Media Authorization

Degree

Master of Science

Graduate Program

Computer Networking

Advisory Committee

Advisor Name	Title
Dr Douglas Reeves	Committee Chair
Dr Mihail Devetsikiotis	Committee Member
Dr Peng Ning	Committee Member

Keywords

policy control
Media Authorization
RSVP
Quality of Service
QoS
Internet Telephony
SIP
COPS

Date of Defense

2002-08-05

Availability

unrestricted

Abstract

KHAN, KHURRAM MATIN. COPS Usage for Managing Media Authorization (Under the
direction of Dr Douglas Reeves)

The unreliable nature of packet networks leads to unpredictable service for the end user. It is
hence desirable to negotiate end-to-end QoS before establishing multimedia calls. Different
mechanisms for the reservation of resources have been defined to allow guaranteed service levels
on packet networks, e.g. Resource Reservation Protocol (RSVP) and Differentiated Services
(Diffserv). Authorization of network resource usage is, however, necessary before the resources
can be reserved for a host and a multimedia session is established. To prevent fraud and facilitate
a coherent view of the resource usage throughout the network, coordination between call
signaling and resource reservation is necessary.

The media authorization framework being developed by IETF addresses these issues. When a
host initiates a multimedia call, it is issued a media authorization token. This token is then
transparently forwarded to the network edge router with the resource reservation request sent by
the host. We have identified a few requirements that are not addressed by the current framework.
For example, the network currently has no way of revoking an already issued authorization.
Proper checks need to be in place to ensure that the token is not misused. Also, there is a need for
closer cooperation between the network elements to allow a consistent view of the resources
reserved by the user. This is of special significance in situations where different administrative
domains involved have service agreements based on the actual resource usage (e.g. for billing
purposes). A solution is proposed to overcome these problems and afford new possibilities in the
framework, like sub delegation of resources. The objective of the proposed extensions is to
provide greater flexibility in the framework and facilitate better coordination between the session setup process and the reservation of resources. Common Open Policy Service (COPS) protocol is
extended to exchange the additional messages and a new COPS client is defined.

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