You need to install the Parallels supplied network device driver. Once that is installed Solaris will accept DHCP update information from OS X via Parallels. It's been a while since I've read it but I recall this is all covered, lightly, in the PDF files that come with Parallels.
Edit: Took some digging, but here's the Sun link: http://www.sun.com/download/products.xml?id=461d6b7d
Last edited: Jun 21, 2007