Sticky question

[arthurlove]

Hi All .. more questions ?

We have a web app that requires sticky sessions. We have to use IP as the marker.

The IP source has comes from a one-2-one NAT range that has a /16 mask.

The sticky config is currently

:

sticky ip-netmask 255.255.255.255 address source WEB_APP_GP
  replicate sticky
  serverfarm SERV_FARM

this seems to work so far,

Question: should this actually be

sticky ip-netmask 255.255.0.0 address source WEB_APP_GP
  replicate sticky
  serverfarm SERV_FARM

thanks again for help

[ciscocsoc]

Hi,

The netmask is used to determine how much of the source address is used to create an entry in the database - i.e. the network component rather than the host component is used.  If you use a /16 mask then the first client to connect will create a sticky database entry and all subsequent clients from your NATTed range will match that entry and be load-balanced to the same server. This is probably not what you want.

I tend to use a /32 mask to balance each client individually but if your clients are evenly distributed across the /16 you could use a /24 mask and create fewer sticky entries in the database.

HTH

Cathy