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I frequently maintain a constant connection with some private servers. I need to be connected with very little latency. The servers measure response time (*ping) in milliseconds.

What factors come into play when calculating this response time? Is it simply the distance between my computer and the server? Does bandwidth fit in here somehow?

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As worded this question is off topic. You could reword to replace gaming with what effects network latency. – Josh K Apr 9 '10 at 23:31
sounds like dup of… – DaveParillo Apr 10 '10 at 5:01
@Dave: that one only focuses on TTL; i think this is a more general question. it's a good related link tho. – quack quixote Apr 10 '10 at 5:44
up vote 2 down vote accepted

Your ping is the time taken for a packet to go from your PC, to the server, and back again. It can be affected by a variety of things, including;

  • Bandwidth of your internet connection
  • What other applications/users are using the bandwidth on your local network
  • Your contention ratio
  • Distance from your local exchange
  • What, if any, throttling / traffic shaping your ISP is performing
  • The load of the server you are connecting to
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So does that mean that a server far away might not necessarily have a high ping? – cornjuliox Apr 9 '10 at 23:45
Yes, that's correct. – RJFalconer Apr 10 '10 at 0:02
@cornjuliox: Correct, a geographically distant server may not necessarily have a high ping, but this is also dependent on the network route and the number & magnitude of routing delays incurred. – rob Apr 10 '10 at 0:03

Bandwidth doesn't directly affect your latency, but the number of routers between you and the server you're connecting to can affect your ping times dramatically. Each router can introduce a routing delay, so generally you want a network route with the fewest number of hops (although that is not always the case, since some networks may be faster than others).

You can use traceroute (tracert on Windows), a command-line program, to check the number of hops between your computer and the server, as well as the latency to each router.

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One other, often over-looked item that I haven't seen mentioned yet: MTU. The mtu represents the largest single packet that can move from your network, through the ISP, to the destination.

Generally it's around 1500, and most routers default to this. HOWEVER, if you're using DSL or some other technology with a packet overhead (PPPoE), you may need to lower your MTU to keep from having packet fragmentation. Packet fragmentation has a DRAMATIC HORRIBLE EFFECT ON YOUR NETWORK SPEED.

As a simple example, if your PC has defaulted to 1500, but your DSL line can only take 1492 (because it's 802.3), every single packet you send will be fragmented into one 1492-byte packet, and 1 8-byte packet...You'll be sending twice as many packets, your collisions will be higher, your overhead will be higher, and your connection will suffer.

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So how do you determine what MTU the DSL line can take? Is it something you'd call the ISP and ask about? – cornjuliox Apr 10 '10 at 21:05
It's almost always 1492, but it should be in your setup packet. – Satanicpuppy Apr 11 '10 at 13:51

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