Thanks for the quick reply.

I've turned off the firewall on the initiator machine and I was able to ping both ways.

Furthermore, the ESX machine that has an active session to the DSS on port 3260 does not "discover" the new volume that I've made available to the appropriate CHAP user.

So, I should formulate more precisely: it is not port 3260 that is the problem, but somehow the target discovery is not working.

Is it possible I've accidentally turned it off at some point?