Plan about 5 minutes to read this.
The topic came up recently that a segment of user workstations on a network I manage were only serviced by 100Mbps ports, and not gigabit. None of us especially had a problem with that, as 100Mbps is an awful lot of bandwidth for the typical desktop user. If 100Mbps seems parsimonious, consider the following.
1. I work from home on a broadband 35Mbps/2Mbps connection.
- Almost every service I use is outside of my house. All of the networks I care for are elsewhere. My e-mail is cloud-hosted. My file-services are cloud-hosted.
- Creative work that I do is local to my workstation, then shipped off via e-mail or file sync when completed.
- Real-time communication is via IM or some flavor of IPT (Skype, VoIP, etc.)
- Most data entry required of me is accomplished via web forms, and many tools that I use are web-based, i.e. the heavy processing and data moving tends to happen on the back-end, not between my client and the remote server.
My Internet bandwidth is adequate. In the download direction, 35Mbps is plenty, even when downloading files 1GB or greater. No, huge files are not delivered instantaneously, but they come down quickly enough. I do feel a pinch when uploading large files, but that’s a rare need.
My point is that life is quite workable on my home broadband connection. By comparison, a symmetrical 100Mbps connection in a typical office environment is a vastly larger connection, and probably one with much less latency.
2. When building out network closets for enterprises, you can often get away with 100:1 oversubscription in real life. I’ve built out lots and lots of network closets over the years. When designing the uplinks, my concern is more about redundancy & resiliency, and less about bandwidth. Why? I know from monitoring that uplinks from closet switches servicing the typical enterprise user just don’t get hit that hard. It just doesn’t matter that you’re giving all those desktop users gigabit access. They’re almost never going to sustain gigabit throughput for any great length of time. Traffic patterns are very bursty over short durations. That lends itself well to high uplink oversubscription.
Another thought is related to the horsepower found in a typical desktop workstation. Can that machine even fill a gigabit pipe? In most cases, no – the disk and/or other buses inside the workstation are going to be a bottleneck. While exceeding 100Mbps isn’t so hard to do, being able to sustain hundreds of Mbps is more of a challenge.
The key here is to know your traffic. Users shuttling around heavy data sets to work on locally (say, video editors) probably have beefy workstations with none of the aforementioned bottlenecks, and are pushing lots of packets across the wire. That’s a different issue than the typical cubicle worker faces. Developers are also folks to keep an eye on, as they love to do things like spin up large database instances on their workstations to run tests against.
3. Gigabit to the desktop costs money.
- How well will your cabling plant do if you start pushing gigabit Ethernet across it? If the plant is CAT5 or higher, it should be okay. I’ll add that in my experience, the quality or age of the cabling installation is less of an issue than some vendors might want you to believe, especially when it comes to servicing workstations. But, it’s still a potential issue. Connections deteriorate. Copper cables that have been resting for years don’t like to be physically disturbed, especially at their punch down points. Cabling that has been feeding desktops for years might be of nominal quality to support gigabit. Running new cable isn’t cheap. Therefore, you need a really good business case to perform a cabling plant upgrade merely to support 100Mbps to gigabit.
- The cost of gigabit switches has come down dramatically, to be sure. In a net-new installation, there’s little to think about. While you might be able to save a few bucks buying the 100Mbps switch model, it’s usually not worth it – you’ll just buy the gigabit switch and be done with it. But what if you’re looking at a network refresh, where the existing closet switches are 100Mbps? Certainly, there are many good reasons to upgrade aging switches. They have an electronic lifespan. Technology moves on, and perhaps you need new features that your old switch doesn’t have, say to support a VoIP deployment. But if the only thing driving the decision to replace a 100Mbps switch is that you’d feel better if those users have gigabit, you might be missing something. Again, know your traffic patterns.
You should never do anything in networking “just because.” Technology exists for a reason. Oftentimes, the way to know whether or not to implement a certain technology is to understand why it exists. In the case of ever increasing Ethernet speeds, you might think, “Well…because faster.” Right. Faster. So by that logic, 10G is better than gigabit, and 40G better than that. “Oh, well 10G to the desktop is just silly. A user would *never* need that sort of bandwidth, and you can’t even get 10G LOMs for workstations with any ease right now anyway. Plus the cabling required. Oh. Hey…” Right. Hopefully, you see what I did there. Yes, gigabit is much less of a cost than 10G, but do your users actually need gigabit? If you’re confident they don’t need 10G, ask yourself why you’re confident that they *do* need 1G.
Am I advocating 100Mbps switches for user workstations across the board? Not really. Except in rare cases, I haven’t installed a fast Ethernet switch for a long time. But I am saying that if you’ve got a bunch of 100Mbps desktop switches that are doing what the users need, then the fact that they are merely fast Ethernet isn’t a good enough reason by itself to want to throw them out.
Now, if you’re a non-technically minded manager wanting to use this article to squash a purchase request, remember that there are a lot of reasons other than simple speed upgrades that would indeed warrant a 100Mbps switch replacement. Listen to your engineering people making the recommendation. That’s why you hired them. ;-)