Network Bandwidth Usage Guideline: Wireless
Purpose
The
Carnegie Mellon Computing Policy establishes a general policy for the use of computing, telephone and information resources. The purpose of this guideline is to establish acceptable practices that support the
policy as it applies to wireless network bandwidth usage.
The main objective of the wireless network is to provide a network connection that can be used virtually anywhere; it is not intended to be a replacement for the wired infrastructure. Because the activity of one wireless network user dramatically affects the wireless performance for other users, Computing Services has established wireless usage limitations and prohibits network services such as web servers, peer-to-peer file sharing, or FTP servers on the wireless network.
This guideline was established to ensure that the Carnegie Mellon community has a clear understanding of proper procedure and usage, and that each machine on the wireless network has access to a fair share of the available bandwidth.
Computing Services reserves the right to modify this guideline as necessary. Any changes to this guideline will be posted to official.computing-news and will be reflected on this web page.
Applies to
This guideline applies to all campus affiliates. This includes students, faculty and staff members as well as guest account holders.
Definition/Clarification
Some services which can have a negative impact on the wireless network are defined below; the following lists are NOT exhaustive. If you need to perform any type of high-bandwidth usage tasks, consider using a wired network connection.
Services which can have a negative impact on the wireless network are listed below, but not limited to the following:
- Web servers
- Peer-to-Peer file sharing
- FTP servers
- Multiplayer Gaming and Game Servers
Many of these services are provided within the overall research and educational goals of the university. Even so, those providing services must do so in a way that does not cause degradation of the entire wireless network.
Additionally, there are other issues which can cause your machine to have a negative impact on network bandwidth. The following list contains some examples and should not be considered to be exhaustive:
- Worm or viral infections
- Compromised systems running ftp, IRC, or other services
- Malicious spyware programs
Some activities may also cause a system to use excessive wireless bandwidth. The following list contains examples and should not be considered to be exhaustive:
- Reinstalling an operating system
- Performing Windows Update or Apple Software Updates
- Downloading and installing applications
- Performing system backups
- Transferring large files (images, video, music, databases) to other systems
Guideline Statement
Computing Services states that no individual service or system running on the wireless network should use more than a total of
750 megabytes (750MB) of bandwidth
per day, regardless of whether it is inbound or outbound.
Initial Notification: Initially, a system will trigger an overuse notification if the 5 day average for either inbound or outbound usage exceeds 750 MBs. To calculate a 5 day average, we use the greatest value of inbound or outbound usage per day. These numbers are totaled then averaged.
Averaging high usage over a 5 day time period allows machines infrequent bursts of activity above the daily limit. As long as the usage totals less than 3750 MBs in a 5 day period, no notification would be issued.
The situation illustrated in the table below WOULD generate an initial overuse notification. However, no notification would be issued if, for example, the spike in inbound usage on Day 2 were only 3105 MB.
(262 MB+ 3105 MB+ 112 MB+ 149 MB + 112 MB = 3740 MB/5 = 748 MB)
| Usage |
Day 1 |
Day 2 |
Day 3 |
Day 4 |
Day 5 |
Total/Average |
| Inbound |
262 MB |
3373 MB |
74 MB |
74 MB |
112 MB |
4008 MB/5=802 MB |
| Outbound |
74 MB |
112 MB |
112 MB |
149 MB |
74 MB |
Notice that, in the following example, the average usage for inbound or outbound traffic respectively does not exceed 750 MBs. However, an overuse notification WOULD be issued since the average of the HIGHER of inbound or outbound usage over this five day period exceeds 750 MBs.
| Usage |
Day 1 |
Day 2 |
Day 3 |
Day 4 |
Day 5 |
Total/Average |
| Inbound |
674 MB |
449 MB |
562 MB |
936 MB |
711 MB |
4006 MB/5=801 MB |
| Outbound |
74 MB |
711 MB |
974 MB |
487 MB |
299 MB |
Subsequent Notification: Once an initial overuse notification has been issued, checks on that machine are performed DAILY.
- A system with over 750 MBs usage (inbound or outbound) in one day would immediately exceed the usage guideline. Continued violations will result in further warnings that may eventually lead to loss of network access.
- A system with 800 MBs of inbound traffic on one day and 850 MBs of outbound traffic on a second day would incur two overuse incidents.
In cases where a user has been asked to disable a service, and does not do so, Computing Services may revoke access to the network and initiate appropriate disciplinary procedures against the user. Disciplinary actions may include loss of network access for 45 days.
User Responsibilities and Procedures
The wireless network is a shared resource and a complimentary service that is NOT intended to be a replacement for the campus wired infrastructure. Because Wireless Andrew coverage is limited, we recommend a wired connection when you need to use a higher limit of bandwidth for your own purposes or when providing a service to others.
Users should be aware that some applications such as peer-to-peer file sharing applications, web servers, SQL applications and others, may turn on servers by default. In most cases, the server portions of these applications can be disabled. Users must also be aware that if a computer is running these services while connected to the wired network, the services should be stopped before connecting the computer to the wireless network.
This site provides access to the Bandwidth Usage Monitoring System that is currently used for Carnegie Mellon's Computing Services wireless and dorm networks. Network usage for the previous five day period is provided.
Revision History
Last Updated: October 19, 2005
Established: February 21, 2003
