Aswath Weblog

Difference Between VoIP and File Sharing

Om mentions about a P2P application called Hamachi. It allows two computers to share files and other resources between the two computers. It can be summarized (may be oversimplified) to be consisting of the following three aspects:

1. Hamachi clients register with Hamachi server, which facilitates in locating other Hamachi clients. Clients are identified by “Hamchi network address”.
2. The server “enables peer-to-peer communications between two computers [in] bidirectional NAT traversal.”
3. Hamachi clients provide application specific functions like user interface and encryption of data.

I am sure you have noticed by now, that the services provided by Hamachi is isomorphic to those provided by a VoIP system: Hamachi server is analogous to SIP proxy server; Hamachi network address is equivalent to SIP address; NAT traversal scheme is the same. Hamachi specific application routine is equivalent to a SIP client that follows SIP signaling protocol and voice codec and also provides a user interface. Cynically speaking then, Applied Networking can easily reposition itself to be a P2P VoIP provider and raise funding instantly.

Seriously though, the industry is developing multitude of software to do two basic functions that are fundamental to IP Communications – client identification and location; NAT/Firewall traversal. Not only it is sufficient to have a single way; but these multiple implementations are undesirable because they all require identity issued from separate entities. In other words, we need a Skype address, a FWD address, a Hamachi address etc. Since this is the only source of revenue, these entities will extract fee from us (protestations notwithstanding). So we need to devise an universal way to do the first two functions and an addressing scheme that is not beholden to one commercial entity. Then all these applications can be used for the specific purpose for which it is designed.