Optimizing Traffic Flow with Port Controls, Port Trunking, and Filters
Traffic/Security Filters
Filter Types and Operation
Multicast Filters
This filter type enables the switch to forward or drop multicast traffic to a
specific set of destination ports. This helps to preserve bandwidth by reducing
multicast traffic on ports where it is unnecessary, and to isolate multicast
traffic to enhance security.
You can configure up to 16 static multicast filters (defined by the filter
command). However, IGMP-controlled filters will override any static multi-
cast filters having the same multicast address as specified by IGMP. The total
of static multicast filters and IGMP multicast filters together can range from
389 to 420, depending on the current max-vlans setting in the switch.
Table 9-10. Maximum Allowed Number of Multicast Filters
Max-VLANs
Setting
Maximum # of Multicast Filters
(Static and IGMP Combined)
1 (the minimum) 420
8 (the default) 413
32 or higher 389
Not e : IP Multicast Filters. Multicast filters are configured using the Ethernet
format for the multicast address. 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). Any static
Traffic/Security filters configured with a multicast filter type and a multicast
address in this range will continue to be in effect unless IGMP learns of a
multicast group destination in this range. In this case, IGMP 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 static
filter resumes control over traffic to the multicast address.
Ca ut ion If Spanning Tree is enabled, then the Spanning Tree multicast MAC address
should not be filtered. (STP will not operate properly if the STP multicast MAC
address is filtered.)
9-38
