UMN:CLI User Manual
V8102
522
no debug nsm mcast {all | fib-
msg | mrt | register | stats | vif}
Disables the debug event.
To display the debugging of Network Service Module (NSM) in the MRIB, use the follow-
ing command.
Shows the NSM debugging status.
10.3.2 PIM Basic
Protocol Independent Multicast (PIM) is the most widely deployed multicast routing proto-
col. It may use the underlying unicast routing information base, but is not dependent on
any particular unicast routing protocol. PIM has two operation modes, which are called
PIM Sparse Mode (PIM-SM) and PIM Dense Mode (PIM-DM), each optimized for a differ-
ent environment.
PIM-SM is a multicast routing protocol efficient for multicast groups that may span wide-
area (and inter-domain) internets. In the sparse mode, routers forward multicast packets
only when they receives explicit join messages from neighboring routers that have down-
stream group members. PIM-SM uses a unidirectional shared tree per group to deliver
multicast traffic, and optionally uses the shortest path tree per source.
PIM-DM is a multicast routing protocol efficient for multicast groups that are densely pop-
ulated across a network. In the dense mode, routers initially flood multicast datagrams to
all multicast routers, since they assume that all downstream systems want to receive mul-
ticast packets. Prune messages are then used to prevent from propagating to routers with
no group members. Both PIM protocols use the same message formats.
The V8102 currently support PIM-SM only.
PIM Messages
The followings are simple descriptions of PIM control messages:
• Hello
PIM routers periodically send hello messages on all interfaces to discover neighbor-
ing PIM routers and to determine which router will be the DR for each subnet.
• Register
Register messages are sent by the DR to the RP when a multicast packet needs to
be transmitted on the RPT. These messages may contain the encapsulated multicast
traffic. Both register and register-stop messages are unicast.
• Register-stop
When receiving the register-stop message, routers stop sending register messages.
These messages are sent from the RP to the sender of the register messages.
• Join/prune
Join/prune messages are sent by routers towards upstream sources or RPs. Join
messages are sent to receive the multicast traffic by building shared trees (RPT) or
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