URHnet Bandwidth Policy
Why Does URHnet Have a Bandwidth Policy?
Housing provides high-speed Internet access as a service to all of our residents.
Unfortunately, all of the bandwidth used by that service costs a lot of money, and
our hardware can only support so much traffic from everyone at any given time. If
every student were to use all of the bandwidth available to them 24 hours a day,
our network would become unusable. Furthermore, the bandwidth used by URHnet is
only a piece of the bandwidth used by the entire University. This includes all
residence halls, university teaching departments, university operation departments,
and users.
To keep URHnet bandwidth from overwhelming the network, Housing has instituted
a set of rate limits that gradually limit the connections of the highest-traffic
users on URHnet, and keep the network working well for everyone. This allows us
to efficiently use our limited bandwidth resources, and continue providing high-speed
access to everyone.
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Rate Limiting Definitions
Rate limiting is the system that is used on URHnet to regulate high-traffic
users. The basic idea behind rate limiting is that the more traffic you
generate, the slower your connection will become. Rate limiting was
implemented as a way of allowing residents to download large files while still
being allowed to use the Internet. If you start a http download and then cancel it,
your "traffic account" will be charged with the full file size.
Except in severe cases, Housing does not
disable connections for excessive traffic.
URHnet tracks traffic over a moving 24-hour period. What this means is
that your limit class will be determined by the amount of traffic you have done in
the past 24 hours. We currently have three limit classes that your
connection can be placed in:
- Unrestricted Class (10 Mb/s): All connections are in this class by default.
Connections in this class are not artificially limited or throttled.
- Restricted Class A (1 Mb/s download aggregate & 32 kb/s upload
per flow): Connections will be limited when they reach a total
of 2GB of traffic in the past 24 hours.
- Restricted Class B (128 kb/s download aggregate & 128 kb/s upload aggregate): Connections will be further
limited when they reach a total of 5GB of traffic in the past 24 hours.
Aggregate means that your bandwidth is shared among
all of the connections in your Restricted Class.
Rate limit classes affect your computer only - your roommate(s) have separate
traffic records and will not be rate limited if you go over your limits. Rate limits
affect all of your traffic, both on-campus and off-campus. You may be
disconnected or contacted
if we feel you are abusing the bandwidth policy by changing your MAC address or if we see
continually heavy traffic (ie. in Class B for days at a time, etc...)
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Monitoring Your Bandwidth
To view your traffic over the past 24 hours, as well as information on what limit class
you are in, you can visit http://www.housing.uiuc.edu/traffic.
There are a few things about this page that merit explanation. First, the page reports
both your input and output. Input is data coming from your computer,
and output is data coming into your computer. Our rate limit thresholds are based
on the total of these two traffics, which can be seen at the bottom of the page.
This page reports your traffic in bytes. The limits of 2000MB and
5000MB are equal
to 2,000,000,000 and 5,000,000,000 bytes, respectively. Flows are another way of
representing web traffic. You will not be rate limited based on flows.
Please note: if you download a file via http and then cancel it
mid download you will see the full file size reflected on the traffic pages.
As you can see in the following picture, the computer has been ratelimited for heavy traffic.
Numbers in red are highlighted because the ratio of input to output matches the ratios that
are often seen when filesharing programs are in use. The computer moved from unrestricted,
to class A, then into class B when the heavy traffic continued.

Only traffic between your computer and a computer off campus will be represented
on this page. This means that traffic that does not leave campus will not be counted
against your totals for rate limits. There is no absolute way to tell what traffic is
considered on or off campus, but a good guideline is that most web addresses that end in
".uiuc.edu" are on campus.
If you want a more real-time count of your traffic, visit
http://flowstats.cites.uiuc.edu/cgi-bin/traffic.cgi.
Note this count will always be lower than the number that determines your rate limit class.
NEW! Running Windows Vista? Try out the URHNet Monitor Widget.
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