Thanks in advance

up ifconfig $IFACE txqueuelen 10000

The up allows any following command to be executed when the interface is brought up. This way the line is in the same place as the rest of the interface configuration.

As for the proxy servers (squid), what is recommended? to increase the tx queue length? or the oposite?

Knowing that we are using server hardware…

Please advise

It should be noted however that increasing the txqueuelen value is a sure fire way to oversaturate your network interface buffers which may cause excessive jitter and DNS resolve timeouts. The default Linux txqueuelen value of 1000 is already way to high, and reducing this value to some much smaller number will reduce the likelihood of your network interface buffers being oversaturated. Personally I have had good results setting the value to 200.

Basically TCP must be able to have packets dropped quickly in order for the server to know that there is network congestion occurring. The size of the value determines how much buffering takes place(where # of packets translates to number of seconds of data being buffered). When this value is too high the feedback mechanism, which forms the basis for the network congestion avoidance algorithms in TCP, fails, meaning instead of packets being dropped thereby signalling that there is congestion. When the server is unaware of congestion due to excessive buffering the inevitable retransmission of packets only occurs once the problem has gotten too severe- and thus gigantic latencies are introduced, latencies equivalent to the number of seconds buffered according to the value set in txqueuelen. So the smaller the txqueuelen value, the better are the chances that TCP’s congestion avoidance algorithms can do their job-hence resulting in higher transfer speeds, and the less likely that the buffers will be overfilled leading to gigantic timeouts when retransmission inevitably occurs. Google Jim Gettys and bufferbloat for a better explanation.