Example 7: Selective Multicast Forwarding Through Gre Tunnels - Black Box SmartPath LWN602A User Manual

SmartPath EMS VMA begins transferring the configuration to SmartPath AP3 and displays the Monitor > Access Points >
SmartPath AP Update Results page where you can observe the progress and the result of the operation.
After SmartPath AP3 reboots to activate its new configuration, it tries to reconnect with SmartPath EMS VMA. However, it can-
not do so because it is a mesh point that now belongs to the cluster1-test cluster while its portals—SmartPath AP1 and 2—are
still using their original configurations in which they are members of cluster0. This loss of connectivity will continue until you
update the portals, which you do next.
5. Repeat the previous steps to update SmartPath AP1 and SmartPath AP2.
After they reboot and activate their new configurations, check the status of their CAPWAP connections by looking at the
CAPWAP column on the Monitor > Access Points > SmartPath APs page with the View mode set as Monitor. After a few
minutes, all three SmartPath APs will reestablish their connections.

8.7 Example 7: Selective Multicast Forwarding through GRE Tunnels

SmartPath APs can selectively block or allow broadcast and multicast traffic through GRE tunnels to reduce traffic congestion. You
can filter traffic either by using a blacklist to block all broadcast and multicast traffic (or to block all except to a few select destina-
tions) or by using a whitelist to allow all broadcast and multicast traffic (or to allow all except to a few destinations).
Most IP cameras are designed to send video via an IP multicast protocol. When configuring a number of cameras to send video to
a central monitoring facility through a GRE tunnel, the SmartPath AP terminating the tunnels at the monitoring facility automati-
cally forwards the multicast traffic it receives back through all the other GRE tunnels to the cameras because they are all members
of the same multicast group. Not only is this unnecessary, but it can also create a very large amount of traffic. This is particularly
problematic because GRE does not have a mechanism for pruning traffic, and multicast traffic arriving at a GRE tunnel endpoint
must be replicated on all outgoing tunnels.
Figure 8-12. Selective multicast forwarding through GRE.
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Chapter 8: Basic Configuration Examples
Page 101