LevelOne GTL-2691 - Manual (Page 550)

C HAPTER 15 | Multicast Filtering
Layer 3 IGMP (Query used with Multicast Routing)
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C ONFIGURING IGMP
I NTERFACE
P ARAMETERS
Use the Multicast > IGMP > Interface page to configure interface settings
for IGMP.
The switch uses IGMP (Internet Group Management Protocol) to query for
any attached hosts that want to receive a specific multicast service. The
hosts may respond with several types of IP multicast messages. Hosts
respond to queries with report messages that indicate which groups they
want to join or the groups to which they already belong. If a router does
not receive a report message within a specified period of time, it will prune
that interface from the multicast tree. A host can also submit a join
message at any time without waiting for a query from the router. Hosts can
also signal when they no longer want to receive traffic for a specific group
by sending a leave-group message.
If more than one router on the LAN is performing IP multicasting, one of
these is elected as the “querier” and assumes the role of querying for
group members. It then propagates the service request up to any
neighboring multicast router to ensure that it will continue to receive the
multicast service. The parameters described in this section are used to
control Layer 3 IGMP and query functions.
N OTE :
IGMP Protocol Status should be enabled on all the interfaces that
need to support downstream multicast hosts (as described in this section).
N OTE :
IGMP is disabled when multicast routing is disabled (see "Enabling
Multicast Routing Globally" on page 708 ).
CLI R EFERENCES
◆ "IGMP (Layer 3)" on page 1261
P ARAMETERS
These parameters are displayed:
◆ VLAN – VLAN interface bound to a primary IP address.
(Range: 1-4093)
◆ IGMP Protocol Status – Enables IGMP (including IGMP query
functions) on a VLAN interface. (Default: Disabled)
When a multicast routing protocol, such as PIM, is enabled, IGMP is
also enabled.
◆ IGMP Version – Configures the IGMP version used on an interface.
(Options: Version 1-3; Default: Version 2)
◆ Robustness Variable – Specifies the robustness (or expected packet
loss) for this interface. The robustness value is used in calculating the
appropriate range for other IGMP variables, such as the Group
Membership Interval, as well as the Other Querier Present Interval, and
the Startup Query Count (RFC 2236). (Range: 1-255; Default: 2)
Routers adopt the robustness value from the most recently received
query. If the querier's robustness variable (QRV) is zero, indicating that