How to perform hardware sizing for SAP Webdispatcher

Hi,

We are moving from R/3 4.7 to ECC 6.0. So, this will bring a concept of integrated ITS as a ICF service.

So, to leverage that we would be needing a SAP Webdispatcher in front.

Can any one of you please provide how can I do Hardware sizing for SAP webdispatcher. We are planning to have a new hardware in place, because we are expecting high load user load and would not want to overload our ECC box.

THanks

Anjali