How can nginx supports more than 64511 concurrent backend connections?

Cliff Wells cliff at
Wed May 23 16:46:31 UTC 2012

On Tue, 2012-05-22 at 04:05 -0400, diogin wrote:
> Hello nginx fans,
> I'm using nginx (with ngx_redis2 module) as a redis client, and would
> like to establish more than 64511 keep alive connections with a redis
> instance. The local port range of Linux is limited to 64511, so I'd like
> to set up multiple ip addresses for nginx machine, but I don't know how
> to tell nginx to bind local port on multiple ip addresses. Anyone has
> the experience? Thanks in advance.

You could also give the redis instance multiple IP addresses and then
put those instances in an upstream block so Nginx will round-robin them.

The port limitation is 64K per address *pair* (local, remote), so you
can add IP's on either side to get the same effect.


More information about the nginx mailing list