Using Multicast in Your Network
Fixed Switch Configuration Guide 19-13
PIM Support on Enterasys Devices
Enterasys devices support version 2 of the PIM protocol as described in RFC 4601 and draft-ietf-
pim-sm-v2-new-09.
The PIM specifications define several modes or methods by which a PIM router can build the
distribution tree. Enterasys stackable C3 and C5 and standalone G-Series platforms support sparse
mode (PIM-SM).
The PIM specifications define several modes or methods by which a PIM router can build the
distribution tree. Enterasys devices support sparse mode (PIM-SM), which uses only those routers
that need to be included in forwarding multicast data. PIM-SM uses a host-initiated process to
build and maintain the multicast distribution tree. Sparse mode routers use bandwidth more
efficiently than other modes, but can require more processing time when working with large
numbers of streams.
Key Features
Key features of PIM-SM are the following:
• Uses IGMP to propagate group membership information
• Sends hello messages to determine neighbor presence and configuration
• Sends join/prune messages to determine the need to retain multicast route information for a
particular group on an interface
• Sends assert messages to resolve conflicts that occur regarding inbound interfaces
• Uses routes in the Multicast Routing Information Base (MRIB) to perform its reverse path
forwarding check
PIM-SM Message Types
Enterasys PIM-SM-enabled devices use the following message types:
Note: PIM is supported on Enterasys fixed switches on which advanced routing has been enabled.
Refer to “Licensing Advanced Features” on page 4-8 for more information.
Table 19-1 PIM-SM Message Types
Message Type Description
Hello These messages announce the sender’s presence to other PIM-
SM devices. The hello packet includes options such as:
• Hold time — the length of time to keep the sender reachable
• Designated router (DR) priority — used to designate which
PIM-SM device will act on behalf of sources and receivers in
the PIM-SM domain
Register These messages are used by a source’s DR to encapsulate
(register) multicast data, and send it to the rendezvous point (RP)
— a PIM-SM router designated as the root of a shared tree.
Register-Stop These messages are used by the RP to tell the source’s DR to
stop registering traffic for a particular source.
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