ZyXEL Communications MGS3520 Series, Руководство пользователя

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Chapter 25 Multicast
MGS3520 Series User’s Guide
205
Normal Leave Enter an IGMP normal leave timeout value (from 200 to 6,348,800) in miliseconds. Select
this option to have the Switch use this timeout to update the forwarding table for the
port.
In normal leave mode, when the Switch receives an IGMP leave message from a host on
a port, the Switch waits for IGMP reports after the multicast router sends out an IGMP
Group-Specific Query (GSQ) message to determine whether other hosts connected to the
port should remain in the specific multicast group.
This defines how many seconds the Switch waits for an IGMP report before removing an
IGMP snooping membership entry when an IGMP leave message is received on this port
from a host.
Note: The timeout value for each IGMP report will be halved automatically by the Switch
because the robustness variable value (the number of query messages) is set to two
by default to cover the possibility of an IGMP GSQ being missed by IGMP host(s) or
an IGMP report being missed by the multicast router(s) due to network congestion.
Fast Leave Enter an IGMP fast leave timeout value (from 200 to 6,348,800) in miliseconds. Select
this option to have the Switch use this timeout to update the forwarding table for the
port.
In fast leave mode, right after receiving an IGMP leave message from a host on a port,
the Switch sends out an IGMP Group-Specific Query (GSQ) message to determine
whether other hosts connected to the port should remain in the specific multicast group.
This helps speed up the leave process.
This defines how many seconds the Switch waits for an IGMP report before removing an
IGMP snooping membership entry when an IGMP leave message is received on this port
from a host.
Group Limited Select this option to limit the number of multicast groups this port is allowed to join.
Max Group Num. Enter the number of multicast groups this port is allowed to join. Once a port is registered
in the specified number of multicast groups, any new IGMP join report frame(s) is
dropped on this port.
Throttling IGMP throttling controls how the Switch deals with the IGMP reports when the maximum
number of the IGMP groups a port can join is reached.
Select Deny to drop any new IGMP join report received on this port until an existing
multicast forwarding table entry is aged out.
Select Replace to replace an existing entry in the multicast forwarding table with the new
IGMP report(s) received on this port.
IGMP Filtering
Profile Select the name of the IGMP filtering profile to use for this port. Otherwise, select
Default to prohibit the port from joining any multicast group.
You can create IGMP filtering profiles in the Multicast > IPv4 Multicast > IGMP
Filtering Profile screen.
IGMP Querier
Mode The Switch treats an IGMP query port as being connected to an IGMP multicast router (or
server). The Switch forwards IGMP join or leave packets to an IGMP query port.
Select Auto to have the Switch use the port as an IGMP query port if the port receives
IGMP query packets.
Select Fixed to have the Switch always use the port as an IGMP query port. Select this
when you connect an IGMP multicast server to the port.
Select Edge to stop the Switch from using the port as an IGMP query port. The Switch will
not keep any record of an IGMP router being connected to this port. The Switch does not
forward IGMP join or leave packets to this port.
Table 84
Advanced Application > Multicast > IPv4 Multicast > IGMP Snooping (continued)
LABEL DESCRIPTION