Televes Coaxdata 1Gbps-HDTV COAX+PLC 1ETH+1SFP User Manual
Page 24
CoaxManager
™
User Guide
24
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IGMP join
: Message sent by a device or set-top box that wants to join a multicast group.
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IGMP leave
: Message sent by a device or set-top box that wants to leave a multicast group.
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IGMP Querier (Only IGMPv3)
: IGMP querier is a IGMP function that imlements a Query
message (usually Multicast Routers and Switches) where the network periodically ask if anyone
is joined to a multicast group. Devices members of multicast channels respond with IGMP
message indicating which groups are connected. IGMP Querier can send request for all
multicast groups or requests for each managed multicast.
To ensure membership of multicast channels and that information is as updated as possible, and thus
prevent a user leaves a channel waste bandwidth, in the IGMP protocol timers are defined:
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Group Specific Queries Timeout (Only IGMPv3):
This timer expires after 260 seconds where
no IGMP Queries sent to a specific group that has been registered in the device. A registered
group is one in which there are set-top boxes that indicate their membership of a particular
group responding to IGMP queries that are sent periodically by the Multicast Router. If the timer
is disabled, once registered multicast flow will not be removed from the table even if no queries
made by the Multicast Router.
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All system Queries Timeout (Only IGMPv3):
This timer expires after 260 seconds where no
IGMP Queries sent to all multicasts groups that has been registered in the device. If the timer is
disabled, no multicast flow will be removed from the table by expiration timer associated with All
System IGMP Query requests.
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Group Membership Timeout (Only IGMPv3)
: This timer controls the period that goes from the
transmission of a query to the STB and the lack of response. Delete a stream for which there
has been no reply from any STB. If the timer is deactivated the stream will remain active
indefinitely.
Normally when a router or switch has no response from a Set-Top Box after several attempts asking
about membership in a multicast channel, delete the device joining to the multicast stream, setting a
conservative procedure regarding use of bandwidth and causes the master stops transmitting these
streams to the coaxial network after expiration of timers.
EN