LAN transfer speeds cat6 vs wireless

Question

The current setup is one file server (windows) serving 3 other windows 7 computers (identical spec) via cifs/windows file sharing. The server is connected via ethernet cable to router(netgear wndr3700), and all other computers connect wirelessly (all with n capable wireless cards on 5Ghz) via the same router.

I am experiencing very slow transfer speeds, maxing out at just 3MB/s, and closer to 2MB/s average. according to the router spec, i should be seeing speeds closer to 30MB/s.

To test whether it is my network card(s) I have connected one of the computers via ethernet and performed the test again from server to client and back- a more respectable 8MB/s average, but still not great ( i deal with files of 500MB upwards).

I have priced up cost of cables vs wireless. A new router is considerably cheaper than wiring the place with cat6 cable (or cat5e for that matter).

What sort of speed increase will I be able to get via a new router? What sort of speeds would wired get me(considering it is about 5X more expensive than the new router to wire properly)?

Answer 1

Your AP (router) is capable of transmitting each individual packet at 300Mbps (Megabits/sec: 1,000,000's of 1-bit bits per second)…
IF AND ONLY IF the client is also capable of the same 300Mbps flavor of Wi-Fi…
…AND the AP is configured to use 40MHz-wide channels in the given RF band…
…AND if it's using the 2.4GHz band, there are no "40MHz intolerant" devices in range…
…AND either "no security" or "WPA2" (AES-CCMP) security is enabled…
…AND WMM (QoS) is enabled…
…AND the client is close enough to have a strong enough signal AND the AP is on a clean enough channel for low enough noise for the 300Mbps signaling scheme to be successfully received.

So that gives you a list of things to check on, to make sure you're making the most of your 300Mbps AP.

But that's only the rate at which each individual packet is sent. Wi-Fi has a lot of overhead, so even with the efficiency boost that was introduced by 802.11n's support for frame aggregation, your TCP over IPv4 throughput is only going to be a maximum of 80% of the signaling rate you get. And the overhead of the SMB/CIFS protocol and the latency of the software and disk are going to drag that down even more.

So even if you were getting the 300Mbps signaling rate, your CIFS file I/O throughput might only be 60% of that, for 180Mbps / 8.4 = 21MiB/sec (MebiBytes/sec = 1,048,576's of 8-bit Bytes per second).

The 2-3MiB/sec you're getting is typical of 802.11a or 802.11g networks in fairly ideal conditions. Check through each thing on that list of ANDs above to see what's going on in your case.

When it comes to making your decision of wiring up vs. upgrading Wi-Fi, remember to factor in the cost of upgrading the Wi-Fi on the three client machines. For example, if you decide to fully modernize to 1300Mbps 802.11ac (3 spatial streams, 80MHz-wide channels), you're probably looking at $180 for the AP, $100 for something like an ASUS PCE-AC66 for each desktop, and $70 for an ASUS USB-AC56 for each laptop (and the USB dongles only do the 2-spatial-stream, 867Mbps flavor of 802.11ac).

So for going to 802.11ac Wi-Fi you're talking $300-500 for the potential of getting in the 40-90MiB/sec range for your CIFS-based file transfers.

Going to gigabit Ethernet would give you the potential of a steady 100MiB/sec (that estimate already accounts for CIFS overhead), but your fileserver might not be fast enough to keep up with that.

Note also that gigabit Ethernet requires that the switch and the PCs' NICs be gigabit-capable, in addition to your Ethernet cables being Cat5 or better. It doesn't matter if you have Cat6 cable if your equipment only knows how to send and receive 100Mbit signals over it.

For me, the decision would come down to how mobile I want the Windows 7 boxes to be. If they're desktops, or if they're laptops that never move from their desks, I'd probably take the expense of wiring properly, to have guaranteed bandwidth without all the potential range/signal/noise hassles of Wi-Fi. But if one or more of them are laptops that people actually like to move around with, I'd probably go for modern 802.11ac.

Answer 2

Buying a new router will not give you as much a boost as you think.

1. if you buy a new router with better WiFi (a/b/g/n/ac). You could potentially need to upgrade your wireless cards. A new router will probably not give you the speed boost you are looking for.
2. Wireless speeds advertised are far greater then you will ever get in real life.
3. Hardwire (cat5/6) will always be faster then WiFi, but still slower then advertised (cable speed). Cat6 for gig will not give you 1024MB transfer speeds. You also need gigabit NIC, gigabit switches.

Another option you have is to install PowerLine in your house. The speeds are faster then WiFi, but not as fast as hard line. It is more expensive then a new router, but less then wiring your whole house.

Moral of the story: Hard Wire is King, then powerline, then wireless. As always you get what you pay for.

Answer 3

First - Cat 6 is a waste of money - Cat5e is all you need for gigabit. I run about half a mile of it (all in less than 100m chunks, of course) on switches that report error rates, and see no point whatever to buying Cat 6 - it won't really run 10G-baseT, and if it won't to that, there is no point to it - and little enough point to something that will.

Wirewise, you'll generally find that in real life, 100Mbit wire will beat wireless unless you are sitting in the same room as the router and a patch-cord would be all the wiring you'd need to do there. Gigabit blows wireless out of the water. However, gigabit also tends to exceed other components of the chain - some cheap gigabit adapters will make the gigabit link light light up, but can't actually move data that fast. Given that the router you have purports to have gigabit ports, it's intertesting that you get much slower wired connections through it than with a crossover cable, so it may be of that class. It's certainly "home-consumer-grade" equipment. Disk subsystems may not really have the throughput to keep up, etc. Gigabit just moves the squeeze point to somewhere other than the network speed, but that's a good thing, generally.

Wirelessly, again, unless you have short clear line of sight, 2.4 Ghz may well move data a lot faster than 5 Ghz - it penetrates building materials better, so you get more signal, so you get a better connection, so data moves faster. Assuming you have dual-band, try it. I was utterly unimpressed with my shiny new 5 Ghz wireless AP when I got the first one and saw 5Mbit connections on 5 ghz and 20Mbit on 2.4 for the same client computers. Unless 2.4 is so polluted your local router is overwhelmed by other signals around you, 2.4 beats 5 in most cases. You don't have to have empty air, you simply need to be the AP closest to your equipment with the best signal, and 2.4 can often do that in your own space better than 5 GHz can.

IMHO, spend the money once and wire the place, and get a real switch since the netgear slows you down on wires.

As for real-life, limited by whatever, speeds on wire, I can't say for your particular hardware and software, but my Mac, connected by gigbit to a 3 com gigabit switch, connected by gigabit to a Mac server, pulls somewhere around 360Mbit (45MByte), so I'd guess you could see the 40MByte you saw with a crossover cable if you were paying attention to b .vs. B when you wrote that part. When connected to a USB2 disk, rather than the internal disk, that drops to 67Mbit or so, as the USB is the bottleneck there.

Add: You might also try whichever computer gets the best signal on 5Ghz on 5, and the others on 2.4 - that will reduce contention for airtime (among your computers) if the 5 ghz with best signal is not too much worse than when on 2.4 Ghz.