Multi Level Cluster

What is Multi-Level Cluster?

A cluster which has different regions is called Multi-Level Cluster where each region has its own origin for a stream. Ant Media Server can be scaled in different physical locations. You can set the node group parameter of the servers to create regions. Still you can make all nodes be in the same region by setting all node group parameters with the same value or using it with default. But separating the nodes into regions has some advantages in performance. Because each region will have their own origin node for a stream and the edges in a region will pull the stream from the origin of their region.

How does it work?

Let's clarify the the case with an example scenario. We have two scenarios

1. Publisher & Players in the same cluster
2. Publisher & Players in the different clusters

Let's remember the traditional scenario

Publisher & Players in the same cluster

1. Publisher starts a stream and it is assigned to the Origin1 instance in the Region1
2. Player1 who is close to Region1 instance requests to play the stream.
3. Player1 is assigned to Edge11 instance to receive the stream in Region1
4. Since the Origin1 is the origin of the stream, Edge11 will pull stream from Origin1.

Publisher & Players in the different clusters

1. Player2 who is close to Region2 requests to play the stream.
2. Player2 is assigned to Edge21 instance in Region2
3. Edge21 checks the origin of the stream.
   • Since there is no origin instance in Region2 to play the stream. It assigns itself as the secondary origin for that stream in Region2.
   • Edge21 pulls the stream from the Origin1 (main origin) in Region1.
   • Edge21 sends the stream to Player2.
4. Player3 who is close to Region2 requests to play the stream.
5. Player3 is assigned to Edge22 in Region2.
6. Edge22 checks the origin of the stream. Since Edge21 is a secondary origin for the stream in the Region2, it pulls the stream from Edge21 and serves to Player3.

How to configure?

You can set the node group (or region) of a server in 2 ways:

Configuration file (offline)

You can set it as nodeGroup=GROUP_NAME in conf/red5.properties file.

REST API (online)

You can set it by calling POST Method AMS_URL/rest/changeServerSettings and passing node group in JSON format as follows. {"nodeGroup":"GROUP_NAME"}

You should configure the Load Balancer to forward Publish and Play requests to the best region. If you have a global cluster in different geolocations,you should have a Load Balancer like Route53.