Latency...

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attilathegorilla

213 posts

Master Geek

Topic # 23613 4-Jul-2008 08:11

Hi guys,

Just wondering if you could enlighten me. What does latency depend on? I`ve got pretty good line stats, I`m quite close to the exchange, but my PING results are around 130 ms consistently. At the moment I`m still with Xtra`s limited upstream plan, so could that be a reason? Or is this figure normal?

Cheers.

If honest work and justice are not enough - we'll get a lawyer.

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Reply # 142820 4-Jul-2008 08:16

Distance national or internatincal route its taking. This can be seen by a tracert.

Quidam

291 posts

Ultimate Geek

Reply # 142822 4-Jul-2008 08:27

Latency is a somewhat vague term. Can you be more specific about your problem?

As a reference to your ping results, I get less than 20ms (average) pings to my default gateway (Telstra clear cable)

Unfortunately, I'm getting intermmitent "lag spikes" with ping results above 100, or even much higher, to the point of causing a complete time-out on the ping command.

This is killing my online gaming.

"There is no way to Peace -Peace is the Way" (A. J. Muste)

attilathegorilla

213 posts

Master Geek

Reply # 142829 4-Jul-2008 08:52

[URL=https://www.speedtest.net][IMG]https://www.speedtest.net/result/291720931.png[/IMG][/URL]

I`ve got no specific issues, though when I last played online, on a US server, I was experiencing a lot of lag.

But the reason I`m wondering about this now is that a lot of people seem to have much lower values, and I`d like to know if there`s anything I can do to improve my latency.

If honest work and justice are not enough - we'll get a lawyer.

attilathegorilla

213 posts

Master Geek

Reply # 142832 4-Jul-2008 08:57

If honest work and justice are not enough - we'll get a lawyer.

Quidam

291 posts

Ultimate Geek

Reply # 142835 4-Jul-2008 09:09

Ok, looking at your speedtest results I notice your upload is very slow. I think lag is pretty much guaranteed with that sort of upload -especially on an american server, regardless of the high ping issue.

(I assume the server you are pinging to is the most optimal -you might want to try one or two others -for example I get the best results with Napier and then Auckland -Wellington (where I live) gives poor results)

"There is no way to Peace -Peace is the Way" (A. J. Muste)

michaeln

211 posts

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Reply # 142850 4-Jul-2008 09:54

There are four sources of network delay: forwarding, queuing, propagation and serialisation.

Forwarding Delay

Forwarding delay is the amount of time that it takes to receive a packet, decide where to send it, and then start transmitting the packet. For modern routers this time is measured in 10-100μs.

If the packet has to be specially processed, for example, an encrypted packet or a firewall, the delay may rise to a few ms.

Forwarding delay is generally insignificant.

Queuing Delay

Queuing delay is the amount of time that a packet has to wait in a queue while other packets are being transmitted. It varies from 0, for an uncongested link, up to the sum of the amount of time to send the packets queued ahead of it. It is thus dependant on the serialisation delay.

Sometimes a router may elect to drop a packet rather than delay it too much.

Queuing delay is generally insignificant except when the link becomes congested, at which point it can rise to become the dominant source of delay.

Propagation Delay

Propagation delay is the amount of time it takes the signal to traverse a physical link. It is thus based on the speed of light.

The speed of light in optical fibre is about 65% of that in a vacuum; the speed of light in copper is about 75%. Nevertheless, fibre is generally preferred owing to its lower error rate and support for longer distances.

Propagation delay is insignificant for short links, but the dominant component for long links.

Serialisation Delay

Serialisation delay is the amount of time it takes to send the bits of a frame out of the interface. It depends on the number of bytes in the packet and the speed of the port.

Serialisation delay varies from a few μs, for high speed (Gbps) links, to hundreds of ms for slow links and large packets.

Some devices attempt to accumulate several packets and send them together in order to reduce errors, which effectively lengthens the frame size and increases the serialisation delay.

Serialisation delay tends to dominate at low speeds but becomes insignificant at high speeds.

Effect of devices

Cable Modems tend to add a few ms at most to the delay (serialisation delay is small on cable modems), but ADSL suffers from high serialisation delay coupled with error correction that can easily add 25ms of delay.

attilathegorilla

213 posts

Master Geek

Reply # 142853 4-Jul-2008 09:59

So after all, is there anything I can do on my side to improve my latency? A better modem or some sort of configuration settings?

If honest work and justice are not enough - we'll get a lawyer.

johnr

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Reply # 142857 4-Jul-2008 10:03

attilathegorilla: So after all, is there anything I can do on my side to improve my latency? A better modem or some sort of configuration settings?

Faster upload speed will help! a little bit

attilathegorilla

213 posts

Master Geek

Reply # 142874 4-Jul-2008 10:25

I`ve switched over to a FS/FS plan with Xnet, though they haven`t put me through yet, should be today or tomorrow. I`ll retest it then.

If honest work and justice are not enough - we'll get a lawyer.

michaeln

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Reply # 142879 4-Jul-2008 10:35

See if you can get interleaving turned off. That impacts latency (it's described under 'Serialisation delay' in my post. Interleaving is the 'accumulate a few packets and send them out together' bit).

Note that propagation delay to the USA (West coast) is a little over 100ms (round trip). Until we figure out how to increase the speed of light, this number is not going to get smaller.

michaeln

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Reply # 142882 4-Jul-2008 10:42

attilathegorilla:

I`ve got no specific issues, though when I last played online, on a US server, I was experiencing a lot of lag.

But the reason I`m wondering about this now is that a lot of people seem to have much lower values, and I`d like to know if there`s anything I can do to improve my latency.

People in the US, playing on a US server, will always have a much lower PING, owing to not having to traverse 100ms+ (measured in lag, due to speed of light) of the Pacific Ocean. Are you saying that you have a much higher ping time that others in NZ, or are you just comparing to the others in the game?

attilathegorilla

213 posts

Master Geek

Reply # 142909 4-Jul-2008 11:43

michaeln:
attilathegorilla:

I`ve got no specific issues, though when I last played online, on a US server, I was experiencing a lot of lag.

But the reason I`m wondering about this now is that a lot of people seem to have much lower values, and I`d like to know if there`s anything I can do to improve my latency.

People in the US, playing on a US server, will always have a much lower PING, owing to not having to traverse 100ms+ (measured in lag, due to speed of light) of the Pacific Ocean. Are you saying that you have a much higher ping time that others in NZ, or are you just comparing to the others in the game?

Naah I know I can`t expect to keep up with the locals on a US server, but just looking at my pin to the Auckland speedtest server, it`s 130 ms or more and others are posting values below 100, often much below.

If honest work and justice are not enough - we'll get a lawyer.

Fraktul

836 posts

Ultimate Geek

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Reply # 142959 4-Jul-2008 13:56

michaeln:
Propagation Delay

Propagation delay is the amount of time it takes the signal to traverse a physical link. It is thus based on the speed of light.

The speed of light in optical fibre is about 65% of that in a vacuum; the speed of light in copper is about 75%. Nevertheless, fibre is generally preferred owing to its lower error rate and support for longer distances.

Propagation delay is insignificant for short links, but the dominant component for long links.

Copper is not opaque so the speed of light is copper is not relevent - you are reffering to the speed of electromagnetic wave propogation outside a copper wire.

michaeln

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Master Geek
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Reply # 142963 4-Jul-2008 14:11

Fraktul:
Copper is not opaque so the speed of light is copper is not relevent - you are reffering to the speed of electromagnetic wave propogation outside a copper wire.

No, I'm referring to the speed of electromagnetic radiation propagation (c, familiarly the 'speed of light') through copper. I.e. 'light' in this case meaning photons, for which copper is anything but opaque, given the appropriate frequency of photon. Likewise, 'copper' in this context could encompass UTP, STP or various waveguides with a diverse range of dialectrics. The formula is no less relevant and for the copper based transmission media 'about 75%' is a perfectly fine approximation.

Detruire

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Reply # 142978 4-Jul-2008 15:21

attilathegorilla:
Naah I know I can`t expect to keep up with the locals on a US server, but just looking at my pin to the Auckland speedtest server, it`s 130 ms or more and others are posting values below 100, often much below.

Speedtest pings mean as much as a politician's word; almost nothing.

You'd be better off pinging a server with the 'ping' command.

rm *

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