How to trace browser logon process (ABAP, SPNEGO, SNC)

Hi all,

We are currently trying out the SAP Single Sign-On client using SPNEGO on the ABAP application server.

Everything works fine (most of the time ) on both: SAP-GUI, bsp's, its, web dynpro for ABAP, etc.

But sometimes in the browser I am presented a logon screen instead.

Can anyone of you experts point out a trace method that shows me the logon procedure/sequence going on between the browser client and the backend? Perhaps an existing trace tool on the ABAP side?

Thanks in advance

Peter