Testing Network Bandwidth
Between your workstation and the CRC compute resources there are a number of components in the network infrastructure. Examples include: your machines network card, network cabling, routers, switches, and wall jacks. If you seem to be experiencing bandwidth limitations and slow response times you can use the following utilities.
Speedtests
Depending on where you’re connecting from, there are two different tests to try.
Connecting from on Campus
If you’re already on the campus network use the test below. This is better suited for testing connections from campus to the CRC Data center.
Test Connection speed to Union Station: https://ndt.crc.nd.edu/speedtest/
If your results are subpar (check How to Interpret Results below), contact us at CRCSupport@nd.edu. Please include the following in an email:
Your location on campus (building and room number)
Wired or Wireless Connection
Connecting from outside of Campus (Home network etc)
If you’re connecting from home, use the OIT Speedtest.
Note
CRC Engineers cannot help you diagnose home connections. If you see errant or unexpected results from the above test, we recommend contacting your Internet Service Provider.
How to Interpret Results
The results of a speed test can be confusing. Below you’ll find a quick explanation of each result shown. Note that these explanations are simplifications of the intricate details involved with network connections. If you’d like more in depth explanations of the utilities used to garner the results, we encourage you to perform an online search for the term you’re interested in.
What is Ping?
Ping is essentially a call and response to the server you’re trying to connect to. Your computer will send a small number of packets to the server and the server responds with its own.
The result shown is the average amount of time it takes to send out a message and receive an answer from the server. Generally, ping results can be interpreted as below.
Result |
Impact |
|---|---|
< 35 ms |
Great, extremely stable connection. |
35 ms - 60 ms |
Very good, no issues. |
60 ms - 95 ms |
Acceptable, stable connection. |
95 - 120 ms |
Subpar, issues may appear. |
> 120 ms |
Poor, hindrance to productivity. |
As a rule of thumb, the higher the ping and jitter is the more “lag” you’ll experience with interactivity of a shell.
What is Jitter?
Jitter is related to ping / latency above, it is the generally the amount of time it takes in between receiving successive packs from a ping.
An ideal Jitter is below 30 ms, anything above and it’s possible you’ll see some inconsistencies in connection response.
Download Speed
Download speed measures how fast you can pull data from the server you’re testing with. When connecting to the CRC Data center, this is usually limited by the machine / network you’re connecting from. Generally, the higher the number is means a better download experience. The number will be listed in Mbps, which means how many Megabits you’re pulling by the second.
You’ll only need a large number here if you plan on pulling or downloading data from the CRC servers, for this purpose the higher the better. Anything about 25 Mbps should work fine for this. Any number lower than 15 Mbps and you’ll have extended download times for larger amounts of data.
Note
Connection speeds for upload and download are usually measured in bits per second, while storage is measured in bytes per second. There are 8 bits in one byte, so 25 Mbps != 25 Megabytes per second.
Upload Speed
Upload speed is the converse of download speed above, it is the measurement of how fast you can push data from the computer you’re connecting from to the CRC servers. The higher the number the better if you plan on uploading a large amount of data. If you’re not concerned with upload data, this number isn’t all too important.
Home networks are usually limited to around 3 Mbps, which will work fine in most cases. Should you need to upload a large amount of data, try connecting from campus or let us know about your situation at CRCSupport@nd.edu and we’d be happy to make a recommendation.