So, as I have been trying to make a copy of my ReadyNAS NV+ data, I decided to take another look at my overall home network bandwidth between computers.
In a past survey of TCP benchmarking tools, I came across an excellent TTCP utility. Its simple, its easy to compile under Unix variants including MacOS, and there’s a pre-compiled binary for Windows platforms as well.
I thought I’d jot down a few notes before I forget them and have to figure it all out again.
First, lets remind ourselves of the maximum bandwidth for various types of connectivity, this table sums it up.
A couple of notes about the wireless specifications –
802.11g – Operates at a maximum physical layer bit rate of 54 Mbit/s exclusive of forward error correction codes, or about 22 Mbit/s average throughput.
802.11n – Operates at a maximum raw data transfer rate ranging from 54 Mbit/sec to 600 Mbit/sec. Actually achieved speeds range from 130 to 160 Mbit/sec.
Ok, so now on to some quick reference configurations for TTCP and some of my real world numbers.
|TTCP Parameters||Bytes Sent||Computed Duration||Actual Duration||Bandwidth|
|-l 65536 -n 2048||134217728||1 sec @ 1Gbit|
|-l 32768 -n 4096||134217728||1 sec @ 1Gbit|
|-l 16384 -n 8192||134217728||1 sec @ 1Gbit|
|-l 32768 -n 76||2490368||1 sec @ 19Mbit|
|-l 16384 -n 152||2490368||1 sec @ 19Mbit|
|-l 32768 -n 2280||74711040||30 sec @ 19Mbit||27.1||21.02 Mbit/sec|
|-l 16384 -n 4560||74711040||30 sec @ 19Mbit||27.8||20.45 Mbit/sec|
|-l 65536 -n 122880||8053063680||60 sec @ 1Gbit||68.2||900.63 Mbit/sec|
|-l 32768 -n 245760||8053063680||60 sec @ 1Gbit||68.3||899.59 Mbit/sec|
|-l 16384 -n 491520||8053063680||60 sec @ 1Gbit||133.3||460.64 Mbit/sec|
For my tests, I was transferring between a Windows 7 Desktop and a Apple Mac-Mini with two switches between the two. All the numbers look pretty good in my book. For the wireless tests, I flipped off the Ethernet interface on the Mac-Mini to force it though the AirPort connected to an AT&T U-Verse Residential Gateway (which is 802.11g.)