Thanks for bringing it back to the list - forgot my own 'reply to all'
advice earlier... :-\


On Sat, Jul 26, 2008 at 1:18 PM, Chris Babcock <[EMAIL PROTECTED]> wrote:
>> IMHO, the 4801 in this case is maxed out and we're not talking about
>> interference anyway.
>>
> Which also brings up the question, how much processing power should be
> needed to carry a wireless link of a given speed?

The 4801 uses a 266MHz x86 processor with SDRAM that probably runs at
either 100 or 133MHz and seems to max out at routing ~30Mbps.  Cisco
1200 APs have a ~200MHz PPC processor with an unknown (to me) memory
bus speed, but I've seen them operate both radios at full saturation
(~50Mbps) without exceeding 70% CPU utilization.  Granted, they're
normally only bridging packets but it illustrates that processor speed
may not be the end-all solution.

Given that the maximum observable throughput for 802.11g is typically
20-25Mbps, I think a system that maxes out at 30Mbps should suffice.
At higher speeds, you'll either have to reduce the amount of
processing you do (less firewalling, bridge interfaces, etc.) or
increase your CPU power until it fulfills your needs.

All that to say, I think the question of processing power v.
throughput is too complicated for a simple equation - you need to take
into account how much processing you're going to be doing on a given
packet, what your peak PPS rate will be, and what the average packet
size will be.  The extremely variable bit will be how much processing
you'll do, which is often dictated by the OS you're running - how high
into the network stack a given packet must traverse.


RB
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