On Solaris 8 and 9, the router alert option is not added with the MLD messages.

Sun has released the patches that fix the missing router alert option for MLDv1. The patch numbers are 108528-24 and 112233-11 for Solaris 8 and Solaris 9, respectively (Sparc version). This also fixes the occurence of the following message that you might have noticed on Solaris boxes:

Oct 21 21:30:23 domreg ip: [ID 976445 kern.notice] ip_option_process: bad opt 0x5