A Proxy server is a protocol conversion server. There are cases that the management application "speaks" one protocol while the managed devices "speak" another protocol. In this case there is a need for a mediation layer to convert between the 2 protocols.

It also happens that a message in one protocol needs to be converted to multiple messages in the other protocol. In this case the conversion process is more complex as the converter needs to collect all the responses from the managed device before it can reply to the original request. Another complex case is that a single request from the EMS is translated to multiple replies from the managed devices.