Dense-mode PIM works best in environments with large multicast groups and a high likelihood that any given LAN has a group member. Dense-mode would be appropriate for the multicasting of the CEO's speech, for example, assuming lots of people want to hear the speech. Sparse-mode is for dispersed groups that aren't densely located in one part of the network. Sparse-mode might be more appropriate for a multicast training class that only a few people signed up for. Sparse-mode is harder to set up, but generally results in less traffic. With dense-mode PIM, the first packet for a group is flooded to all interfaces. Once this has occurred, however, routers listen to prune messages to help them develop a map of the network that lets them send multicast packets only to those networks that should receive the packets. The prune messages also let routers avoid loops that would cause more than one router to send a multicast packet to a segment. Because of the flooding of the first packet for a group, dense-mode does not make sense in environments where a few sparsely-located users wish to participate in a multicast application. In this case, sparse-mode PIM is a better solution. Sparse-mode PIM is quite different than dense-mode PIM. Rather than allowing traffic to be sent everywhere and then pruned back where it is not needed, sparse-mode PIM defines a rendezvous point. The rendezvous point provides a registration service for a multicast group. Sparse-mode PIM relies on IGMP, which lets a host join a group by sending a membership-report message, and detach from a group by sending a leave message. A designated router for a network segment tracks membership-report and leave messages on its segment, and periodically sends join and prune PIM messages to the rendezvous point. The join and prune messages are processed by all the routers between the designated router and the rendezvous point. The result is a distribution tree that reaches all group members and is centered at the rendezvous point. And that's probably more info than you needed!? ;-) Priscilla At 12:05 AM 5/25/2000 +0000, Cristina Hoselins wrote: >All, > >Would you please explain to me, the main reason why you would configure a >router using PIM sparse mode vs PIM dense mode. >Thank you >Cristina >________________________________________________________________________ >Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com > >___________________________________ >UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html >FAQ, list archives, and subscription info: http://www.groupstudy.com >Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] > __________________________________ Priscilla Oppenheimer Phone 541-482-5685 Fax 541-488-1708 Web http://www.priscilla.com ___________________________________ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
