That depends on the type of network you are talking about. For instance, the internet is a network and uses TCP/IP as its protocol. Intranets based on Microsoft Server also use TCP/IP. However, there are other protocols.
Gateway
A Translational Bridge is used to connect networks that use different protocols.
The network device that connect multiple networks that use the same protocol is a ROUTER.
If you use several different protocols (such as TCP/IP and IPX/SPX or Appletalk) then the frame types will be different. Networks can (and do) utilize several different protocols depending on what they need to talk to as clients.
The most common types of bridges are the Beam and Arch Bridges.
application
These are called protocols - a standard set of rules for common communications across networks.
The purpose of a router is to connect dissimilar networks.
Network services, Protocols and Transmission Meida.
There are many ways to communicate between networks. The rules for doing so are called protocols, and there are many known protocols. Some are historical in nature (meaning they have been around a long time) and some are newer ones developed in the last few years. Protocols describe how to communicate and when to communicate. They may be specific to a means of communication (i.e. web traffic, email traffic) or they may be more general (TCP/IP - covering many protocols). Deciding on which protocol to communicate with other networks is based on how the networks communicate currently and what kind of traffic will be transferred between the two. A protocol is designed so that there are common rules regarding communication, so certain protocols will be used to be common between networks. TCP/IP is an example of a very common, widely-used communication protocol.
Protocols are the set of rules to regulating the procedure of communication over computer networks.
Well-known communications protocols are Ethernet, a hardware and Link Layer standard that is ubiquitous in local area networks, and the Internet Protocol Suite, which defines a set of protocols for internetworking, i.e. for data communication between multiple networks, as well as host-to-host data transfer, and application-specific data transmission formats.