ACE - Source IP Hash

[kris-andrews]

Hi All,

I have a serverfarm that is using source ip hash as the load-balancing predictor to ensure that traffic is sent to the same server. The only issue is the traffic does not appear to be distributed evenly due to all the requests coming from a single NAT address as the source.

I now have a NAT pool that will allow the requests to be sourced from different NAT IP's, however i want to ensure that the source ip hashing will achieve the desired load balancing.

Can someone clarify the source ip address predictor and how the netmask determines hows the ip is hashed?

for example if i have multiple source addresses (below), is there a way to calculate how the ip's will be hashed and traffic distributed among 4 servers?

10.1.1.1

10.1.1.2

10.1.1.3

Kris

[Gilles Dufour]

Here is the hash algorithm

((_key) + (_key >> 8) + (_key >> 16) + (_key >> 24))

The _key in this case is the source ip address has an unsigned 32 bits number.

You then do rserver_index = hash % number_of_rserver.

Gilles.

[kris-andrews]

Hi gdufour,

Thanks for your response,

Please could you give me an example based on the algorithm you provided?

Kris