Multicast routing between (remote) networks
icon4 07 15th, 2010| icon3Comments Off on Multicast routing between (remote) networks

Have you ever faced the situation that you want to use Multicast between subnets, but Routers don’t forward it OR the application/device generating the Multicast traffic is using a TTL of 1, so the blocks don’t get forwarded by the router?

Barix developed a “Multicast routing/tunneling” firmware for the Barionet which turns that device into a flexible, multi site multicast forwarder/router. Effectively, it bridges multiple multicast groups between multiple sites, and can also include single hosts. The functionality is independent on the actual protocols used with the Multicast, being it automation, IP Audio, Video, VoIP, SIP or RTP.

Here is the rough concept:

  • A Barionet is installed in every subnet where multicast traffic needs to be pickeed up or delivered.
  • The device(s) does “UDP” tunnelling to forward the Multicast packets to the other Barionet(s) in the other subnet(s). At the same time, they serve as a tunnel receiver/endpoint to receive encapsulated Multicasts from the other networks.
  • Up to 8 independent multicasts (address/port) can be configured, and up to 8 destinations – either Barionets in other networks as tunnel endpoints, or hosts which then receive the packets unicast.
  • The TTL field of the multicast blocks can be “ignored and set to configured value” or handled as usual (decrementing).
  • Tunnelling can be configured to use “IP over IP” or plain UDP – both have advantages and disadvantages.
  • Monitoring of the application is possible via SNMP.

The first customer uses the application to route VoIP/VHF radio traffic between multiple operations centers in a large company. However, applications can be found wherever multicast needs to be routed between subnets and routers, IT providers or policies prevent that.

Please contact Barix if you are interested in that solution!


If you have an application where you need to deliver an RTP stream to multiple devices and your network infrastructure or source does not support Multicast, the Barix RTP replicator software may be the right thing for you.
Intended for Barix Audio over IP solutions, but useable with about any device or application or data, this software runs on either a Barionet or an Annuncicom, receives audio on a socket, and distributes the RTP packets to a list of up to 100 destination address/port numbers. You can also send to broadcast or multicast addresses.

Run on the Barionet, the application can easily forward a 100kbps IP Audio stream at 30-50 blocks per second to more than 100 destinations, with a delay of less than 20ms ! Using Barix hardware for this purpose has a lot of benefits: PC-Free technology, well below 4W power consumption, no moving parts, no themral issues, operational within 5 seconds of power up.

Customers of Barix use that solution since years to generate thousands of RTP streams to distribute IP Audio streams in real time.

.. and if you need to broadcast RTP in a “remote” network, the solution can be used as well … just configure only one target, the broadcast address, install the device in the remote location, and stream RTP to its receiving port. The RTP stream will be rebroadcasted in the destination network (multicast supported too, of course).

Questions ? Contact us !