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    <p>Cable quality is <em>usually</em> kind of a red herring. I'd think more about connecting up a network analyzer to see whether you're getting enough re-transmissions to care about. If you're getting very many, try to isolate where they're happening, and replace the cable(s) that is/are causing the problem. If you're not getting errors that result in re-transmissions, then the cable has (virtually) no effect on latency.</p> <p>Large buffers on NICs and (especially) switches won't, themselves, reduce latency. In fact, to truly minimize latency, you normally want to use the <em>smallest</em> buffers you can, not larger ones. Data sitting in a buffer instead of being processed immediately increases latency. Truthfully, it's rarely worth worrying about, but still. If you <em>really</em> want to minimize latency (and care a lot less about bandwidth) you'd be better off using a hub than a switch (kind of hard to find anymore, but definitely low latency as long as network congestion is low enough).</p> <p>Multiple NICs can help bandwidth a lot, but their effect on latency is generally pretty minimal.</p> <p>Edit: My primary advice, however, would be to get a sense of scale. Reducing a network cable by a foot saves you about a nanosecond -- on the same general order as speeding up packet processing by a couple of assembly language instructions.</p> <p>Bottom line: Like any other optimization, to get very far you need to measure where you're getting latency before you can do much to reduce it. In most cases, reducing wire lengths (to use one example) won't make enough difference to notice, simply because it's fast to start with. If something starts out taking 10 microseconds, nothing you can do is going to speed it up any more than 10 microseconds, so unless you have things so fast that 10 us is a significant percentage of your time, it's not worth attacking.</p>
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    1. POLow Latency Networking Technqiues and Silver-Bullets
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    1. COOne common issue cablers and network admins do is to cut cables longer they need be and then end-up twisting them into the cabin sides to keep things clean and today. The problem with twisted pair signaling is that this kind of action can lead to huge signal degradation which causes problems when considering latencies at the microsecond resolution.
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      1. USGelly Ristor
    2. CO@Gelly: It's digital. There are exactly two possibilities: either it's degrading the signal to the point that packets need re-transmission (which I already advised looking for) or else it's received correctly, and causes no extra latency at all (beyond the ns/ft for the extra wire).
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    3. CONope, he's got a point. At the speeds we're driving networks nowadays, you have to consider transmission as a hybrid analog-digital design, and signal degradation in bent twisted pair cables is really an antenna effect. Antenna effects are without doubt on the analog side.
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