My Server and Client softwares run both on Linux.<br>
The Server broadcasts multicast, the Client listens multicast.

My Client has to migrate to another site,<br>
and unfortunately multicast is not allowed between the two sites :-(

**How to convey multicast between the two sites?**<br>
 - Through TCP or UDP?<br>
 - What tools do you recommend?<br>
 - What about latency?

**I received an good answer about _Cisco_ configuration (GRE),<br>
but one of the network teams do not want to monitor/maintain it,<br>**
=> when transmission will break, support team will spend too many hours to understand and repair.<br>
**=> So, what should be the best alternative to GRE?**

Is there a solution based on _Linux kernel features_ <br>
or on network card capabilities? (low latency is important)<br>
Usage examples are appreciated :-)

----------

* **Currently:** Server and Client on the same site

  ![current network diagram][1]

* **Future:** Server and Client, each one on a different site

  ![Future network diagram][2]

multicast channel: 225.1.0.1:6666

----------

Related questions
-----------------

 - [UPD Multicast (Class D) = How can this be routed over the internet?](http://serverfault.com/questions/136361/)
 - [IGMP/Multicast routing in Linux](http://serverfault.com/questions/191016/)
 - [Multicast accross the subnets](http://serverfault.com/questions/146457/) and RSVP answer
 - [Multiple GRE NAT router](http://serverfault.com/questions/120878/) and "Multiple VPN limitation" link
 - ...

  [1]: http://ditaa.org/ditaa/render?grid=%2B---------%2B+%2B---------%2B%0D%0A%7C+Server++%7C+%7C+Client++%7C%0D%0A%7C+sends+++%7C+%7C+listens+%7C%0D%0A%7Cmulticast%7C+%7Cmulticast%7C%0D%0A%7C+++IP1+++%7C+%7C++IP2++++%7C%0D%0A%2B----%2B----%2B+%2B---%2B-----%2B%0D%0A+++++%7C++++++++++%7C%0D%0A+++++%2B%2B---------%2B%0D%0A++++++%7CLAN+of+site+1%0D%0A++++++%7C%0D%0A++++++%2B---------------------WAN
 [2]: http://ditaa.org/ditaa/render?grid=%2B---------%2B+%2B---------%2B+++++++++%2B-----------%2B%0D%0A%7C+Server++%7C+%7C+++++++++%7C+++++++++%7C+new+host++%7C++%0D%0A%7C+sends+++%7C+%7C+++++++++%7C+++++++++%7C+for+Client%7C++%0D%0A%7Cmulticast%7C+%7C+++++++++%7C+++++++++%7C+++++++++++%7C++%0D%0A%7C+++IP1+++%7C+%7C+++++++++%7C+++++++++%7C+IP3+++++++%7C+++%0D%0A%2B----%2B----%2B+%2B---%2B-----%2B+++++++++%2B--%2B--------%2B%0D%0A+++++%7C++++++++++%7C++++++++++++++++++%7C++++++++++++%7C%0D%0A+++++%2B%2B---------%2B++++++++++++++++++%2B%2B-----------%2B-%0D%0A++++++%7CLAN+of+site+1++++++++++++++++%7CLAN+of+site+2%0D%0A++++++%7C+++++++++++++++++++++++++++++%7C%0D%0A++++++%2B-----------------------------%2B%0D%0A++++++++++++++++++++++++++++WAN