h1. Load-balancing for media streams

!load_balancing_signaling.gif!

*Server1* performs a role of load-distributor for customer Carrier1.
His functions:

* authorize incoming call;
* spread signalling streams across Server2 and Server3;
* when a call is connected, maintain signalling session with Carrier1;
* redirect media streams to Server2 and Server3;
* adding changes to configuration;
* generate graphs;
* periodic activities ([[Invoice generation]], etc). 

*Server1* supports all [[Signalling protocols]] and media formats, as a regular *Smartswitch* installation.

*Server2* and *Server3* act as SBC (Session Border Controller).
Their functions:

* [[Routing]];
* [[Billing]], [[Online billing]] and [[Balances|Balances maintenance]];
* signalling protocols translation
* when a call is bridged, maintenance of signaling session with Carrier2 and Carrier3;
* media streams proxying;
* media streams translation;
* [[VAS]] (if enabled);

After call billing has been done on _Server1_ and _Server2_, they store billing information on _Server1_.

The function distribution is approximate.
In the example below we assume, that resource spending on signalling handling from all customers are approximately equal to resources spendings to other functions ([[Billing]], [[VAS]], etc).
Maximal capacity of such a scheme is defined by maximal capacity by load-distributor *Server1*.
Therefore in example above it's shown how to maximally offload it.
In case if proportions will be different, it's possible to move some of functions from SBC to load-distributor.

[[Распределение обработки медиа потоков|Русский перевод]]