At 04:59 AM 2/4/02, Eve Mitch wrote: >Hi wondering what I should use in a envirionment where I have 2 core >switches 6513 with sup2 and msfc2 and pfc2 modules onboard. >have about 5 access switches 6513 with sup2 modules connected via trunks to >the core. >Lots of users on different VLANs behind different access switch will use the >few multicast stream there are. >how to decide which mode to use PIM DM or PIM SM.
It sounds like dense mode would work for you. The main reason for not using dense mode doesn't apply in your case. Some people disapprove of dense mode because the multicast stream initially goes to all segments, until prune messages come back from PIM-enabled routers. In a network design where most segments (VLANs) should receive the multicast traffic anyway, this isn't an issue. Plus dense mode is somewhat easier to configure because it doesn't require a rendezvous point. From my Top-Down Network Design book: With dense mode, 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. Dense-mode PIM works best in environments with large multicast groups and a high likelihood that any given LAN has a group member, which limits need for routers to send prune messages. 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, which is described in the next section, 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. Priscilla >thanks in advance >Eve ________________________ Priscilla Oppenheimer http://www.priscilla.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=34366&t=34307 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
