ip_hash in active_active nginx setup

[s_n]

Hi all,

we want to use a F5 loadbalancer in front of two nginx instances, which
balance the load to our app-nodes.

The F5 loadbalancer distributes incoming requests via round-robin algorithm
to the two nginx instances.

The nginx instances should be configured to use ip_hash to distribute the
requests to the addnodes ensuring sticky sessions. Specific customer
requirements make the use of cookies to ensure sticky sessions impossible.

I understand, that all nginx instances use the same function to hash the IP
adress. But i am not sure if the distribution of the hash values to the
appnodes happens in a consistent way.

I came across the following discussion on github which indicates that the
same IP address may be forwarded to different appnodes in the scenario
described above:

http://serverfault.com/questions/511763/do-multiple-nginx-servers-load-balance-the-same-ip-address-to-the-same-backend-w

Long story short / tl;dr:

Will different nginx instances forward requests from the same IP always to
the same appnode when using ip_hash as a load balancing method?

Thanks,

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,259046,259046#msg-259046