Abstract: An implementa tion of modified mul ticast in Mobi le IP was presented, in which, the concept o f mobi le multicast gatew ay ( MMG) w as int roduced. MM G was used to ma nage mul tica st in Mobi le IP. There existed two stag es fo r receiving and fo rw arding respectively. The multicast packet s w ere receiv ed by adding MM Git self on to the mul ticast di st ribution tree, or by deliv ering v ia tunnel f rom the home netwo rk of mobi le ho st ( M H) , and the “ tunnel conv ergence” problem was eliminated tho ro ug hly in the meantime. Af ter w hich, acco rding to di fferent situatio ns, multicast packets w ere forw arded f rom MMG to MH wi th set ting up mul ticast dist ributio n t ree in it s region, o r f rom the tunnel to M H di rect ly to gua rantee th e ro uting ef ficiency and multicast reliability. A netwo rk model was int roduced, and the performance o f all schemes w as analy zed. The numerical resul ts show tha t the new pro po sal presents g ood perfo rmance.

Key words: multicast, mobile Internet protocol, mobile multicast gateway