David Taylor <david-tay...@blueyonder.co.uk.invalid> wrote: > Brief background. I have five Raspberry Pi NTP servers, all with a > nominally identical configuration, all with GPS/PPS receivers. Only one > of these is doing any significant work other than running NTP. None of > the devices are acting as servers for other clients. Two are LAN > attached, and three are connected over Wi-Fi. They all have three LAN > servers polled at 32s intervals, and four pool servers (WAN) polled at > 1024s intervals. The I/O shows that input considerably exceeds output. > > Looking at the I/O bytes reported by MRTG for the LAN or Wi-Fi over USB > adapters, I see: > > raspi-1 LAN in: 207 B/s, out: 35 B/s > raspi-2 LAN in: 202 B/s, out: 36 B/s > > raspi-4: Wi-Fi in: 406 B/s, out 40 B/s > raspi-5: Wi-Fi in: 426 B/s, out: 53 B/s > > It puzzles me that the bytes sent to the RPi when Wi-Fi is attached are > about double the bytes sent over the LAN. I would expect most of that > traffic to be the RPi interrogating the three local stratum-1 NTP servers. > > I don't see why there should be double the bandwidth just because Wi-Fi > is used. Is this expected? Could it be that the USB Wi-Fi adapter is > reporting incorrectly? > > I ask here, as most of the traffic will be NTP packets (or it /should/ be!).
On the receive side there is also broadcast traffic. This includes both the usual 255.255.255.255 and subnet-broadcast traffic and the ARP requests, DHCP requests, etc seen on the network. On a larger network this can be considerably higher than what you see. _______________________________________________ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
