Networking
IGMP
Cisco ISA500 Series Integrated Security Appliance Administrator Guide
138
4
STEP 5
Click
Save
to apply your settings.
IGMP
The 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
allows more efficient use of resources when supporting these types of
applications.
The IGMP Proxy mechanism 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. The IGMP snooping is based on the IGMP version 3 that is
backward compatible with the previous versions.
NOTE
By default, the multicast traffic from Any zone to Any zone is blocked by the default
firewall access rules. When you enable IGMP Proxy and want to receive the
multicast packets from WAN to LAN, you need to uncheck the
Block Multicast
Packets
box in the
Firewall -> Attack Protection
page, and create a firewall
access rule to permit the multicast traffic from WAN to LAN. For more information,
see
Configuring a Firewall Access Rule to Allow the Multicast Traffic, page 185
STEP 1
Click
Networking -> IGMP
.
The IGMP window opens.
STEP 2
Enter the following information:
•
IGMP Proxy:
Click
On
to enable IGMP Proxy so that your security appliance
can act as a proxy for all IGMP requests and communicate with the IGMP
servers of the ISP, or click
Off
to disable it.
•
IGMP Version:
Choose either IGMPv1&v2 or IGMPv3.
-
IGMPv1:
Hosts can join multicast groups. There are no leave messages.
Routers use a time-out based mechanism to discover the groups that are
of no interest to the members.