On 04/16/2013 03:28 PM, Roy Sigurd Karlsbakk wrote: >>> I suspect that the single ping packets being lost are an >>> indication of a problem, but this should not impact the users >>> (TCP should look after the re-transmission, etc). Wether this is >>> related to the longer 10-50 second outage I'm not sure. >> >> No, single lost pings are *not* a sign of a problem. It is >> perfectly normal for a network to have random traffic spikes that >> fill a switch's store-and-forward buffers. ICMP pings are >> *datagrams*, like UDP, so they aren't retransmitted when dropped. >> Losing them as infrequently as you say suggests your network isn't >> heavily loaded. > > Switches (unlike bridges) do not use store-and-forward. They use > cut-through, meaning they use store-and-forward for the initial > packet from A to B and then store the path and switch it later, > sniffing the MAC addresses and just use pass-through. Nothing you said changes my statement that switches often drop single packets. The occasional dropped ping is a red herring. A cheap switch that can't ever buffer will simply drop *more* random packets. > As was said, the traffic on the network was minimal, so I really > doubt this had an impact. Getting 30 seconds+ of drops must come from > a bad network stack or a really bad switch, but then again, two > switches were tested, so I doubt the switches alone could do that. We seem to violently agree here. Multiple consecutive drops is a real problem. > What may be doing it, is bad (or perhaps incompatible) bonding > setup. My point was to not prematurely conclude that the problem is in the network. Phil -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
