what is difference between the f5 BIG-IP LTM and the Netscaler

If I may add, here are some additional differences:

1. To amplify EmBee's "more out-of-box functionality" comment, the BIG-IP is a modular architecture. Both products start off as "ADCs" or Application Delivery Controllers - a fancy word for intelligent load balancing, but then the BIG-IP adds modular capability to address different layers of the stack, from a network firewall to application security, optimization, and authentication proxy - layers 3 through 7.

    

2. Citrix configurations are actually easier with BIG-IP. Strange as that may sound, coupled with the Access Policy Manager (APM) module, BIG-IP can displace not just the "gateway" functions provided by Netscaler, but also secure ticketing and even Web Interface, which basically leaves the XML broker and Xen servers. And using an iApp you can configure this all in a matter of minutes.

    

3. Programmability. This is what originally drew me to F5 products many years ago, and something that just keeps getting better. There are now, at least, 4 different application programming interfaces on the BIG-IP:

    

   • iRules - network/protocol control
   • iControls - remote management and automated provisioning
   • iApps - rapid deployment
   • EAVs - ridiculously intelligent monitoring

Netscaler has an API or two, but it doesn't even come close to this.