running a cloud of streaming servers

I have multiple video streaming servers running on my LAN.

For different subdomains.
i.e.
site1.mydomain.com
site2.mydomain.com
site3.mydomain.com
site4.mydomain.com

All the above websites have different content and are different websites.

The front end to the world is apache2 on a server which has public IP.



To be able to reach the streaming server I
embed a javascript in HTML pages
as follows
Code:

<embed .....
var="rtmp://site1.my_domain.com"

>


the problem is the website are many

site1.mydomain.com
site2.mydomain.com
site3.mydomain.com
site4.mydomain.com

each on a separate server.

Each of these four have their own streaming servers the front end to
each of these four is apache running on gateway


If I run rtmp on each of the subdomains  at a
different port

how will I make sure
a request such as

rtmp://site1.mydomain.com
rtmp://site2.mydomain.com

goes to their respective servers.
from the front end server from gateway.

What do I need to handle in this case ?

For handling HTTP requests in this case I use Apache Reverse Proxy
but for rtmp requests I am not clear as which direction to proceed.

What I want is

if I embed a code in javascript as

rtmp://site1.mydomain.com

then request for

rtmp://site1.mydomain.com

rtmp://site2.mydomain.com

goes to the server on LAN which

has

site1.mydomain.com

site2.mydomain.com

respectively.

The gateway is Linux Server.

Which redirects to these websites via Reverse Proxy at apache what more I need to put in my vhosts at

gateway.