Double check my work, please.
by Nathan Huffman · in Technical Issues · 08/02/2006 (6:53 pm) · 4 replies
Can someone please help me solve these problems, so I can compare your results to mine?
I'm usually pretty good with math, but when it it comes to bandwidth vs data size, my brain sometimes "doesn't carry all the ones". (per say).
If I have a 10/100 card in my 'Server PC' that's running at 100mbps (which I've always known as megabits per second, correct?), and every user in my project requires approx 10KB/sec (kilo BYTES)...
How many users max can I have at 'full stress'? (of course, I know I need to cut back for overhead).
My result was over 1,000. What do you get?
Is there any issues with a standard 10/100 card @ 100mbps operating speed on a P4-3GHZ HT PC with 2GB of RAM having 1,000~ connections at once? Hardware or software limitation? There is little processing as far as my application is concerned (so don't think 3D shooter...).
Let me know your opinions. Thank you!
I'm usually pretty good with math, but when it it comes to bandwidth vs data size, my brain sometimes "doesn't carry all the ones". (per say).
If I have a 10/100 card in my 'Server PC' that's running at 100mbps (which I've always known as megabits per second, correct?), and every user in my project requires approx 10KB/sec (kilo BYTES)...
How many users max can I have at 'full stress'? (of course, I know I need to cut back for overhead).
My result was over 1,000. What do you get?
Is there any issues with a standard 10/100 card @ 100mbps operating speed on a P4-3GHZ HT PC with 2GB of RAM having 1,000~ connections at once? Hardware or software limitation? There is little processing as far as my application is concerned (so don't think 3D shooter...).
Let me know your opinions. Thank you!
#2
What do you suggest?
My game is more board game-ish than 3d shooter, so it's not like the processor is hauling crazy over collision detection and stuff for overhead.
08/02/2006 (7:38 pm)
How many users do you think I could have connected at once without putting too much stress on the processor, because of packet processing?What do you suggest?
My game is more board game-ish than 3d shooter, so it's not like the processor is hauling crazy over collision detection and stuff for overhead.
#3
IIRC (it's been about 10 years since I looked at network theory), this is for rough calculations:
Approximate efficiency of CSMA-CD (Ethernet) is 1/(1+5*A), where A is propagation time (PROP) over transmission time of a packet (TRANSP).
I don't know the specifics of your setup, so I'm going to throw out some numbers.
PROP = length of medium in meters / speed of signal through medium in meters/sec
= 250 meters (estimate) / 2.3 *10^8 meters/sec (for coax)
= 1.09 * 10^-5 sec (approx)
TRANSP = size of packet / speed of network
= 620 bits (estimate) / 100 * 10^6 bits/sec
= 6.2 * 10^-5 sec
A = PROP/TRANSP
= 0.176 (approx)
Efficiency = 1 / (1+ 5*A)
= 53% (approx)
So, given the above parameters, the effective transmission rate of the 100Mbps network is about 53Mbps. I'm guessing that about 678 users could be connected (1280 * 0.53). In reality, it will probably be less.
08/03/2006 (4:19 pm)
Not so much a processor limitiation but more of a network one. It depends on how far away the users are, what the packet sizes are, and what the transmission medium is (coax, fibre, etc.)IIRC (it's been about 10 years since I looked at network theory), this is for rough calculations:
Approximate efficiency of CSMA-CD (Ethernet) is 1/(1+5*A), where A is propagation time (PROP) over transmission time of a packet (TRANSP).
I don't know the specifics of your setup, so I'm going to throw out some numbers.
PROP = length of medium in meters / speed of signal through medium in meters/sec
= 250 meters (estimate) / 2.3 *10^8 meters/sec (for coax)
= 1.09 * 10^-5 sec (approx)
TRANSP = size of packet / speed of network
= 620 bits (estimate) / 100 * 10^6 bits/sec
= 6.2 * 10^-5 sec
A = PROP/TRANSP
= 0.176 (approx)
Efficiency = 1 / (1+ 5*A)
= 53% (approx)
So, given the above parameters, the effective transmission rate of the 100Mbps network is about 53Mbps. I'm guessing that about 678 users could be connected (1280 * 0.53). In reality, it will probably be less.
#4
08/04/2006 (6:25 pm)
Jerry, that was exceptional. Thank you. 
Torque Owner Jerry Shaw
Roaming Gamer LLC
Each user requires 10 kBps -> theoretical capacity of 1280 users.
1000 connections at once? You might have some slowdown :) That's a lot of packets to process.