Networking
Configuring IGMP
Cisco ISA500 Series Integrated Security Appliances Administration Guide 172
4
Internet Group Management Protocol (IGMP) is a communication protocol used by
hosts and adjacent routers on IP networks to establish multicast group
memberships. IGMP can be used for online streaming video and gaming, and can
allow more efficient use of resources when supporting these types of
applications.
IGMP Proxy enables hosts that are not directly connected to a downstream router
to join a multicast group sourced from an upstream network. IGMP Snooping
constrains IPv4 multicast traffic at Layer 2 by configuring Layer 2 LAN ports
dynamically to forward IPv4 multicast traffic only to those ports that want to
receive it. IGMP Snooping runs on IGMP Version 3 that is backward compatible
with the previous versions.
NOTE By default, multicast traffic from Any zone to Any zone is blocked by the firewall.
When you enable IGMP Proxy and want to receive multicast packets from WAN to
LAN, you must first uncheck Block Multicast Packets in the Firewall > Attack
Protection page, and then create a firewall rule to permit multicast traffic from WAN
to LAN. For information on configuring firewall rules to allow or deny multicast
traffic, see Configuring a Firewall Rule to Allow Multicast Traffic, page259.
STEP 1 Click Networking > IGMP.
The IGMP window opens.
010 100 20 AF22
010 110 22 AF23
011 010 26 AF31
011 100 28 AF32
011 110 30 AF33
100 010 34 AF41
100 100 36 AF42
100 110 38 AF43
DSCP Value Decimal Value Meaning