Troubleshooting erratic network performance

[Jamon Camisso]

ted leslie wrote:
> i ran into similar issue, but with mine, 
> it was a iptables
> 
>  limit: avg ####/sec burst #  
> 
> type policy, that got exceeded,
> 
> as limit was hit, some people noticed issue, as it was really hit hard, everyone got timeouts.
> 
> you're fine one minute, then the threshold get hits, and boom! users start refreshing away, 
> starts a queue, then the limit is almost always being exceeded, and it melts down,
> 
> as long as your sure no errors or drops in ifconfig, you can rule out  duplex issue to the switch.
> 
> i assume you check the apache error logs?
> 
> i assume with no one hitting it, you get perfect responce?
> to rule aid more in ruling in or out the web server (vs. network), you could 
> use iptables to forward traffic to one of the other boxes.
> 
> as for the arp cache,
> just config the ethernet card (new one), or new box with the same MAC address, to remove the 6 hour cache issue.

No limits in the iptables rules, nothing being dropped by eth0 either, 
so it looks like every packet is getting through, they are just queueing 
up somewhere or something.

ethtool -S eth0 shows the following from overnight:

ethtool -S eth0
NIC statistics:
      rx_packets: 11195495
      tx_packets: 16731374
      rx_bytes: 1105819797
      tx_bytes: 20729600690
      rx_broadcast: 51426
      tx_broadcast: 47
      rx_multicast: 16
      tx_multicast: 6
      rx_errors: 0
      tx_errors: 0
      tx_dropped: 0
      multicast: 16
      collisions: 0
      rx_length_errors: 0
      rx_over_errors: 0
      rx_crc_errors: 0
      rx_frame_errors: 0
      rx_no_buffer_count: 0
      rx_missed_errors: 0
      tx_aborted_errors: 0
      tx_carrier_errors: 0
      tx_fifo_errors: 0
      tx_heartbeat_errors: 0
      tx_window_errors: 0
      tx_abort_late_coll: 0
      tx_deferred_ok: 5303807
      tx_single_coll_ok: 0
      tx_multi_coll_ok: 0
      tx_timeout_count: 0
      tx_restart_queue: 0
      rx_long_length_errors: 0
      rx_short_length_errors: 0
      rx_align_errors: 0
      tx_tcp_seg_good: 683459
      tx_tcp_seg_failed: 0
      rx_flow_control_xon: 5446536
      rx_flow_control_xoff: 25028787
      tx_flow_control_xon: 0
      tx_flow_control_xoff: 0
      rx_long_byte_count: 1105819797
      rx_csum_offload_good: 11158790
      rx_csum_offload_errors: 0
      rx_header_split: 0
      alloc_rx_buff_failed: 0
      tx_smbus: 0
      rx_smbus: 0
      dropped_smbus: 0

Jamon
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