Network Tuning for Dom0 and ODAbase for high speed transfer across WAN links

From OS perspective following is the procedure.

1) Find the Bandwidth delay product (BDP) value and set the network buffer size accordingly. It is calculated as the product of the link bandwidth, and the Round Trip Time.

For example :

For a 1Gb/s network and Rount Trip Time of 0.1s, the BDP=(0.1 * 10^9)/8. On such a network, set the following parameter values under the file : /etc/sysctl.conf
net.core.rmem_max = 12500000
net.core.wmem_max = 12500000
net.ipv4.tcp_rmem = 4096 87380 12500000
net.ipv4.tcp_wmem = 4096 65536 12500000

And increase the following parameters as well :
net.core.netdev_max_backlog = 30000
net.ipv4.tcp_max_syn_backlog = 4096

And then execute the command:
# sysctl -p


a) For both the changes there is no need for a system reboot.

b) Post this change, it is required to monitor the output of the command : “# netstat -s” and check if the following counters are still seen to be increasing :
packets pruned from receive queue because of socket buffer overrun
times the listen queue of a socket overflowed
SYNs to LISTEN sockets ignored
packets collapsed in receive queue due to low socket buffer


Configure on Guest VM and dom0.

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