Routers

1. Operate at the network layer
2. Connect two or moreLANs using the same or different data link protocols but the same network protocol
3. May connect same or different DTL protocols
4. Forward only those messages that need to go to other networks
5. Chooses the best route between networks when there are several routes between them.
6. May be "black boxes" or computers with several NICs
7. Perform more processing on messages thaan bridges thus are a bit slow.

Brouters
1. Operate at both the data link layer and the network layer
2. Connect bothe the same data link type network LAN segments and different data link ones

Gateways
1. Operate at the network layer and sometimes at the application layer
2. Interface two or more dissimilar networks
3. Translate one network protocol to another translate dat formats and open sessions between application programs thus overcoming both hardware and software incompatibilities
4. For example Systems Network Architecture (SNA) alows LAN users to access mainframe aplications data and peripherals