Black Box LGB6026A, Management Manual

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C
HAPTER
16 | Multicast Filtering
Layer 3 IGMP (Query used with Multicast Routing)
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 578 ).
CLI R
EFERENCES
◆
"IGMP (Layer 3)" on page 991
P
ARAMETERS
These parameters are displayed in the web interface:
◆
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
the QRV field does not contain a declared robustness value, the switch
will set the robustness variable to the value statically configured by this
command. If the QRV exceeds 7, the maximum value of the QRV field,
the robustness value is set to zero, meaning that this device will not
advertise a QRV in any query messages it subsequently sends.
◆
Query Interval – Configures the frequency at which host query
messages are sent. (Range: 1-255; Default: 125 seconds)