Policy on Imposing Bandwidth Limits on Network Application Programs

by Raymond Poon

As Internet is becoming the essential path for communications, both the number of applications and the data volume they generate deplete Internet bandwidth rapidly. These include normal network application programs such as FTP, Web, video services as well as other personal applications such as KaZaA (peer-to-peer*(P2P) applications) and ICQ (chat applications).

In order to prevent abuses, to maintain fairness in bandwidth allocations among users (especially the Internet bandwidth), and to ensure the effective management of the bandwidth by the Computing Services Centre (CSC) under various tight-bandwidth situations, it is necessary that a Rate Limit Policy be adopted for the University. The policy below is in fact the common practice of many universities that have successfully curbed and limited the impact brought about by these applications:

Unless prior arrangement has been made with the CSC, each individual computer, by default, regardless of applications it runs, types of services it offers, or protocols it uses (except P2P applications and protocols), will initially be limited to a default allocation of un-guaranteed network bandwidth of no more than 500 Kilobits per second. However, for all P2P applications, regardless of the number of computers they run on, the total combined bandwidth that they can concurrently consume at any given time is also initially limited to a un-guaranteed network bandwidth of no more than 500 Kilobytes. These initially allocated bandwidths will be allowed to burst up to 1.5 Megabit per second when bandwidth permits. However, the CSC can, with reasonable justifications, apply one or more of the following measures on any networked computer without prior notification:

  • Adjust the value of the default bandwidth allocation
  • Adjust the number of bandwidth increments or decrements
  • Adjust the value of each bandwidth increment or decrement
  • Block all network traffic (both outbound and inbound) or disconnect the machine concerned from network.

It is planned that this Policy on Rate Limiting will be effective on 1 September 2002 and that the initial bandwidth allocation and allowable burst rate for each Internet application will be reviewed annually.


*peer-to-peer (P2P) is a type of network in which each workstation has equivalent capabilities and responsibilities. This differs from client/server architectures, in which some computers are dedicated to serving the others. On the Internet, P2P is a type of transient Internet network that allows a group of computer users with the same networking program to connect with each other and directly access files from one another's hard drives. Napster and Gnutella are examples of this kind of P2P software.