Introduction

ISL Conference Proxy Private Cloud is a technology which enables you to install more than one ISL Conference Proxy for added reliability and performance. All instances of ISL Conference Proxy are automatically synchronized at all times - each has a complete copy of user database and other control data, e.g. session information. In case of a failure of one or more servers, other servers are not affected and can continue their operation without interruptions. In such cases, ISL Online products will detect that the connection to the current server was broken and will automatically reconnect to another available server.

If it is possible, ISL Conference Proxies should be installed in geographically separated locations, so that a failure of one Internet Service Provider’s network connection will not severely affect the normal operation of your ISL Private Cloud. As an added benefit, the users of ISL GRID will be redirected to the closest proxy to obtain faster network connections.

Note: You need two or more Corporate Server Licenses to setup your own ISL Private Cloud. Please contact us (sales@islonline.com) for more information on purchasing appropriate licenses.

Benefits

• Higher reliability, failure of a single server does not affect other servers
• Better performance, the load on a single server is lessened
• Geographically separated installations of proxies provide:
  • Resistance to ISP and internet backbone failures
  • Better performance, clients are redirected to the closest server

Technical details

Each ISL Conference Proxy server consists of two applications – ISL Conference Proxy itself and a custom DNS server. Load balancing policy is implemented on DNS level, even before the client connects to ISL Conference Proxy. DNS server and ISL Conference Proxy must be running on the same physical machine and are connected through a channel which informs DNS server about current status of the Private Cloud.

Database replication is performed over connections between proxies. Each proxy makes connections to all the other proxies in the Private Cloud, resulting in maximum replication speed.  Replication algorithm also includes automatic conflict resolution - if a server has been disconnected from the Private Cloud for a longer period of time, the algorithm will automatically update that server’s database from other servers in the Private Cloud.  Even in the worst case, where several servers were not interconnected due to network failures and were operating independently, databases will still be correctly synchronized when the servers restore connections.

Connection procedure

1. Client requests resolution of Private Cloud DNS name, client’s DNS server connects to one of ISL Conference Proxy DNS servers:
   
2. Client is redirected to the most appropriate server based on load balancing policy:
   
3. When a server failure occurs (e.g. network failure, hardware problem etc.), the client automatically connects to the other server:
   
4. ISL Online products' sessions are always hosted on a single server to minimize network delays. If a server failure occurs, all clients from the server migrate to the other server (picture below represents an example for ISL Light).
   

Please continue to the first step: Define servers.