UT collect the MAC info for all end hosts & ip addresses & user name for only some host is displayed but ip's & username for most of hosts is not displayed.
Usernames for Windows end hosts come from the UTLite utility running on each end host. Make sure that UTLite is properly installed and running on the Windows end hosts which do not have username information. Usernames for UNIX end hosts are polled by Campus using the rusers protocol. Make sure rusersd is running on your UNIX workstations.
As for IP information, UTLite will provide that if it is setup correctly. However, most of the IP addresses comes from UT polling the routers which have been Data Collected for their ARP tables. Make sure that the routers which contain the missing MAC/IP mappings are showing up as green with a router icon on the Topology Map.