> LAN-to-gateway traffic (e.g., a test FTP of a large file from the > gateway to a machine on one of the LANs) begins to degrade as the > LAN-to-internet traffic increases. That's not surprising, but it > degrades disproportionately, i.e. when the FTP begins to show > intermittent stalls, the total traffic visible at the router on the > internet side of the gateway is only in the just-over-10Mb/s range. > > Once we get to this point, no matter how many more LAN-to-internet > connections become active, the router on the internet side never sees > much over 10Mb/s of traffic. We're not losing data or having an > unusual number of connection timeouts; each connection just slows > down. We figured on some slowdown for NAT, but not 80%+. > > LAN-to-LAN traffic that doesn't involve the gateway behaves more like > we'd expect, but I'm not sure that eliminates the switch as the > culprit. Maybe it is time for some kernel networking tuning. This will definetly require more memory, but should speed things up. This is on a CentOS 4 machine .. I don't have a CentOS 3 machine to test on. Add the following lines to /etc/sysctl.conf net.core.rmem_default = 67108864 net.core.wmem_default = 67108864 net.core.rmem_max = 67108864 net.core.wmem_max = 67108864 net.ipv4.tcp_mem = 4096 67108864 67108864 net.ipv4.tcp_rmem = 4096 67108864 67108864 net.ipv4.tcp_wmem = 4096 67108864 67108864 net.ipv4.ip_local_port_range = 32768 65535 net.ipv4.tcp_max_syn_backlog = 8192 After adding these lines, run "sysctl -p" Hope this helps. Barry