[erlang-bugs] Client port limitations on Linux

[Vinod Panicker]

Hi,

We're using tsung (http://tsung.erlang-projects.org/) as  a load
generator to test our application server. During testing we found that
tsung was not able to generate over 65k clients, even though it was
configured to use multiple ip addresses available to the host machine.

On debugging, we found that though tsung was binding to the different
ip addresses, it was not reusing a port number across the ip
addresses. eg. if it has established a connection to the server using
ip address 192.168.66.74 and port 12000, it will not establish another
connection using ip address 192.168.66.75 and port 12000.  It
considers port 12000 to be used.

We concluded that the problem was actually in erlang - attaching a
test program that uses 2 hard coded ip addresses to connect to a tcp
server. They can be run to verify this issue. A simple tcp server will
be required to accept the connections.

The server and client machines were appropriately configured to handle
a large number of connections and erlang processes.

Regards,
Vinod.
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