User Guide

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Router User Guide
M ULTICASTING
Multicasting Overview
Traditional multicast routing mechanisms such as Distance Vector Multicast Routing Protocol
(DVMRP) and Multicast Open Shortest Path First (MOSPF) were intended for use within regions
where groups are densely populated or bandwidth is universally plentiful. When groups, and senders
to these groups, are distributed sparsely across a wide area, these “dense mode” schemes do not
perform efficiently.
Protocol Independent
Multicast (PIM)
Protocol Independent Multicast (PIM) protocols route multicast packets to multicast groups. PIM is
protocol independent because it can leverage whichever unicast routing protocol is used to populate
unicast routing table. There are two modes of PIM protocol – Dense mode (DM) and Sparse mode
(SM).
Alcatel supports SM only in version 8.0 and higher.
PIM-DM floods multicast traffic throughout the network initially and then generates prune messages
as required. PIM-SM attempts to send multicast data only to networks which have active receivers.
This is achieved by having a common Rendezvous Point (RP) known to the senders and receivers
and by forming shared trees from the RP to the receivers.
PIM-SM is described in RFC 2362.
PIM Commands The general PIM commands supported in this release are:
Global parameters
Enable PIM /configure/ip> pim
Configure PIM mode /configure/ip/pim> mode [sparse | dense]
Configure Assert Holdtime /configure/ip/pim> assert-holdtime <time>
Configure Hello Interval /configure/ip/pim> hello-interval <time>
Configure Hello Holdtime /configure/ip/pim> hello-holdtime <time>
Configure Hello priority /configure/ip/pim> hello-priority <value>
Configure Join/Prune
Holdtime
/configure/ip/pim> join-prune-holdtime <time>
Configure Join /Prune
Interval
/configure/ip/pim> join-prune-interval <time>
Configure MRT Period /configure/ip/pim> mrt-period <time>
Configure MRT Stale
Multiplier
/configure/ip/pim> mrt-stale-mult <number>