FortiGate Next Generation Firewall utilizes purpose-built security processors and threat intelligence security services from FortiGuard labs to deliver top-rated protection and high performance, including encrypted traffic.
Article Id 232400
Description This article explains the scenario, in the FortiGate firewall where the client is located in one VLAN and the phone server is located in another VLAN.
Scope FortiOS.

While making a call from the client to the server, the user could not hear audio. There is already a configured VLAN to VLAN multicast policy but for some reason, it is not working.


As per this scenario, there is already configured multi-cast policy. Make these changes in the firewall and check.


To prevent the TTL for forwarded packets from being changed:


# config system setting
    set multicast-ttl-notchange enable


To enable multicast forwarding in NAT mode:

# config system setting
    set multicast-forward enable


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