Lucent Technologies P550 - Manual (Page 248)

Managing Intelligent Multicasting (Layer 2 & Layer 3)
15 -2 Cajun P550/P220 Switch Operation Guide
a client of) a multicast session. Router ports are ports that are attached to (or in the path
to) multicast routers and must be treated specially. All multicast traffic on a VLAN must
be forwarded to the router.
You can manually create and delete multicast sessions through the user configuration.
The addition of client and router ports can also be performed manually. Dynamic
intelligent multicasting is achieved through IGMP snooping, LGMP (Lucent Group
Membership Protocol), or CGMP (Cisco Group Management Protocol) snooping. All of
these mechanisms are based on the assumption that the client host is running IGMP,
requesting membership in the IP multicast session.
Note: If there is no multicast session created for a multicast flow in a VLAN, then
that multicast flow will be flooded to all ports on the VLAN. Intelligent
multicasting must be enabled for any dynamic intelligent multicasting to be
active.
Layer 3 Dynamic Intelligent Multicasting
IGMP snooping is supported for VLANs that have IGMP interfaces enabled. This is the
recommended means of supporting dynamic intelligent multicasting in Layer 3. For all
VLANs that do not have an IGMP interface enabled, the Layer 2 dynamic intelligent
multicasting mechanisms (LGMP client and CGMP snooping) are supported.
Note: For Layer 2 or Layer 3 LGMP to perform properly, VLAN IDs must match
between switches. Specifically, if two switches are connected with a
non-tagging link, the port-default VLANs of the ports connecting the two
switches must be the same. This is because the VLAN is embedded in the
LGMP message; and the receiving switch maps the LGMP message to the
specified VLAN.
IGMP Snooping
IGMP snooping is only supported in Layer 3. As IGMP reports are received by the switch,
IGMP sessions are created. Intelligent multicast sessions are created and the ports on
which these reports are received are added to the appropriate sessions. When the IGMP
session is terminated, the associated intelligent multicast session is deleted.
Note: IGMP snooping is only available for VLANs that have an IGMP interface
enabled.