HP 4108GL Management And Configuration Manual page 370

Multimedia Traffic Control with IP Multicast (IGMP)
The Switch Excludes Well-Known or Reserved Multicast Addresses from IP Multicast Filtering
N o t e :
IP Multicast Filters. IP multicast addresses occur in the range from
224.0.0.0 through 239.255.255.255 (which corresponds to the Ethernet multi-
cast address range of 01005e-000000 through 01005e-7fffff). Where a switch
has a static Traffic/Security filter configured with a "Multicast" filter type and
a "Multicast Address" in this range, the switch will use the static filter unless
IGMP learns of a multicast group destination in this range. In in this case, IGMP
dynamically takes over the filtering function for the multicast destination
address(es) for as long as the IGMP group is active. If the IGMP group
subsequently deactivates, the switch returns filtering control to the static
filter. This operation applies to the HP Procurve Switch 1600M, 2400M, 2424M,
4000M, and 8000M, but not to the Series 2500 switches and the Switch 4108GL
(which do not have static traffic/security filters).
Reserved Addresses Excluded from IP Multicast (IGMP) Filtering.
Traffic to IP multicast groups in the IP address range of 224.0.0.0 to 224.0.0.255
will always be flooded because addresses in this range are "well known" or
"reserved" addresses. Thus, if IP Multicast is enabled and there is an IP
multicast group within the reserved address range, traffic to that group will
be flooded instead of filtered by the switch.
Number of IP Multicast Addresses Allowed
Multicast filters and IGMP filters (addresses) together can total up to 255 in
the switch. If multiple VLANs are configured, then each filter is counted once
per VLAN in which it is used.
15-20