HP ProCurve 6200yl Multicast And Routing Manual page 50

Multimedia Traffic Control with IP Multicast (IGMP)
Excluding Well-Known or Reserved Multicast Addresses from IP Multicast Filtering
N o t e s :
2-20
IP Multicast Filters. This operation applies to the ProCurve Series 5400zl
switches, the Series 3500yl switches, the switch 6200yl, the Series 5300xl
switches, as well as the 1600M, 2400M, 2424M, 4000M, and 8000M, but not
to the Series 2500, 2650, Series 4100gl, Series 4200vl, or 6108 switches
(which do not have static traffic/security filters).
IP multicast addresses occur in the range from 224.0.0.0 through
239.255.255.255 (which corresponds to the Ethernet multicast 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 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 deacti­
vates, the switch returns filtering control to the static filter.
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.