LevelOne GEL-1061, User Manual

Page: 406 / 500

Chapter 14
| Multicast Filtering
Layer 2 IGMP (Snooping and Query for IPv4)
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When IGMP snooping is disabled globally, snooping can still be configured per
VLAN interface, but the interface settings will not take effect until snooping is
re-enabled globally.
◆
Version Exclusive – Discards any received IGMP messages (except for multicast
protocol packets) which use a version different to that currently configured by
the IGMP Version attribute. (Options: Enabled, Using Global Status;
Default: Using Global Status)
If version exclusive is disabled on a VLAN, then this setting is based on the
global setting configured on the Multicast > IGMP Snooping > General page. If
it is enabled on a VLAN, then this setting takes precedence over the global
setting.
◆
Immediate Leave Status – Immediately deletes a member port of a multicast
service if a leave packet is received at that port and immediate leave is enabled
for the parent VLAN. (Default: Disabled)
If immediate leave is not used, a multicast router (or querier) will send a group-
specific query message when an IGMPv2 group leave message is received. The
router/querier stops forwarding traffic for that group only if no host replies to
the query within the specified time out period. Note that this time out is set to
Last Member Query Interval * Robustness Variable (fixed at 2) as defined in RFC
2236.
If immediate leave is enabled, the switch assumes that only one host is
connected to the interface. Therefore, immediate leave should only be enabled
on an interface if it is connected to only one IGMP-enabled device, either a
service host or a neighbor running IGMP snooping.
This attribute is only effective if IGMP snooping is enabled, and IGMPv2 or
IGMPv3 snooping is used.
If immediate leave is enabled, the following options are provided:
■
By Group – The switch assumes that only one host is connected to the
interface. Therefore, immediate leave should only be enabled on an
interface if it is connected to only one IGMP-enabled device, either a
service host or a neighbor running IGMP snooping.
■
By Host IP – The switch will not send out a group-specific query when an
IGMPv2/v3 leave message is received. But will check if there are other hosts
joining the multicast group. Only when all hosts on that port leave the
group will the member port be deleted.
◆
Multicast Router Discovery – MRD is used to discover which interfaces are
attached to multicast routers. (Default: Disabled)
◆
General Query Suppression – Suppresses general queries except for ports
attached to downstream multicast hosts. (Default: Disabled)
By default, general query messages are flooded to all ports, except for the
multicast router through which they are received.