Many different network services are regularly used here at CLASSE. They include SAMBA, remote applications on WinApp, and the Compute Farm. We all connect to the CLASSE network in different ways – some people use desktops wired into the CLASSE network, others use Cornell’s EduRoam/RedRover service, and some access CLASSE from their home. Performance of network services varies with the type of service, the type of computer used to access the service, and the network connections between the two. Remember that when you’re on wireless in Wilson, Newman, and the PSB, you are using a non-CLASSE network, even though you’re in a CLASSE building.
Why is my access to CLASSE Network services so slow?
There are many connections, routing devices and computers in the network between your computer and the CLASSE service you are trying to use. That network connection path usually is the most influential part of the performance of the network service. Usually, the closer you are logically to the service (i.e. the fewer devices there are between your computer and the server), the faster it works. However, if the network is limited to 10Kbps (10 thousand bits/second) – nothing except getting a faster connection will make files transfer faster than the 10Kbps. Within the CLASSE network, getting faster connections is possible, given sufficient funding and time. However, we can’t make EduRoam or Red Rover faster – the same wireless networking is provided across all of Cornell by CIT and is shared by all users of the service. We also can’t convince Time Warner or Verizon to upgrade their infrastructure – though you may be able to purchase a faster connection from whichever ISP (Internet Service Provider) you’re using. So, if you hit the “speed limit”, does that mean all is lost? Not necessarily …
The second major factor is the application you use. X-Forwarding is very slow over the Internet. It sends many individual packets, each of which has to be confirmed before it sends the next one. That works well on a local network with few devices in between, but forwarding each of those packets among the many devices on the public Internet results in a large delay for each packet. However, we provide an alternative to X-Forwarding known as X2Go. Our X2Go service is quite a bit more responsive due to “tricks” (including caching) that it uses to make X-Forwarding much more efficient. Similarly, SAMBA is a very “chatty” protocol designed for use over ethernet on Local Area Networks, so SFTP (which is not so chatty) tends to be more efficient for remote file transfers. It is often far faster and more efficient to access CLASSE services via X2Go (so that all of your computing is done on the remote CLASSE computers) rather than transferring files to your local computer and back. There’s also a known issue with certain SAMBA clients, specifically those in Mac OSX, which results in their being quite slow. Try using Windows 7 on the same connection, for instance, and you may find SAMBA access is much faster.
What’s the problem? Is it my ISP?
If you’re having problems accessing Internet services in general, including those at CLASSE, it’s important to determine what the specific problem is. There are two great articles, one from Microsoft, and one from LifeHacker on what might be the issue in your connectivity:
http://lifehacker.com/why-is-my-internet-suddenly-so-slow-1525144792
If your WiFi or router seems to be the problem, there are several things you can do. We have some links to local support providers on our Wiki: https://wiki.classe.cornell.edu/Computing/OutsideSupport.
What diagnostics can I perform, and what do they tell me?
Finally, as suggested in a recent CLASSE Computing newsletter, a speed test can tell you about the actual network link from your device to the Internet. Your ISP often will tout speeds of up to some value. Going to http://www.speedtest.net and running the test will tell you (as of the test time) what speeds and ping times you’re actually getting. If they seem very low to you, contact your ISP.
The Download speed result will tell you roughly the speed with which you can download files. This is mostly relevant to copying a file from SAMBA to your local disk or using SFTP and performing a download operation. This doesn’t really tell you what it’ll be like to edit or browse to a file on SAMBA.
To determine that, you need to look at the ping time (Latency) and upload speed. This is because latency (the time for a single packet to get from the server to you) will affect the time it takes for you to change which file is selected on SAMBA and for edits to be shown on the server (this is very simplified). Additional information about Latency is available:
Latency/Bandwidth Explanation #1 and Latency/Bandwidth Explanation #2
In contrast, the upload speed will affect how long it takes to send those changes over the net up to SAMBA.
Similarly, with LogMeIn for instance, the download speed will affect the color quality and resolution selected, but latency (ping times) will really affect how quickly the remote PC can react to a “click”.
So what do I do?
So in summary – what does this all mean?
If you’re at Cornell, on Red Rover or EduRoam, as we said in our newsletter, CIT provides an assessment tool at https://ratemywifi.cit.cornell.edu/. You can run the test multiple times, and it’s useful to use this tool each time you have an issue that might be related to Red Rover or EduRoam. This will help CIT diagnose weakness in their wireless.
If you’re at the lab, one thing to try is to connect to LNS protected via a wire to rule out latencies and the like from Red Rover or EduRoam.
If you’re not on the Cornell Campus, there’s usually not much that can be done without drastic changes, some of which you can make. For example, you can get a better router, sometimes you can change your ISP, and you could upgrade your computer if those are the problems. Alternatively, you can try a different workflow. For example, some users synchronize files between a USB disk and SAMBA, or do a bulk copy before they work on the files locally and sync changes back once they’re done. Sometimes, using a different program like X2Go instead of X-Forwarding, or working remotely on a lab computer via LogMeIn will solve performance problems.