1. Network Communications Chapter 14 LAN Interconnection Devices

2. Repeater:Layer 1 (Physical) Bridge:Layer 2 (Data Link) Switch:Layer 2, 3, or 4 (Transport) Router:Layer 3 (Network) Gateway:Layer 7 (Application) CSU/DSU:LAN to WAN connection

3. Connecting LAN Segments with a Repeater Physical Layer Physical Layer Figure 14.1

4. OSI Reference Model for a Bridge Homogeneous Network Expansion Physical Layer Physical Layer Data Link Bridge Figure 14.2

5. Bridge Types Learning (Transparent) Bridge –Requires no administration –Discovers connected terminals Source routing bridge –Used in token ring networks –Follows the information in the frame header Bridge Port #1 Port #2 Figure 14.3

6. Router OSI Reference Model Works at the Network Layer Can handle non-homogeneous networks Determine “best” data path for each frame Physical Layer Physical Layer Data Link Network layer Network layer Router Figure 14.4

7. Routers Connecting LANS Static Router –Manual administration Dynamic Router –Automatic –Exchanges information with peers –Standard protocol and algorithm (Dykstra) Figure 14.5

8. Gateway Works at the application layer A high-level protocol converter Physical Layer Physical Layer Network Transport Session Presentation Data Link Application SNA TCP/IP Figure 14.6

9. Switch Already covered in chapter 12

10. CSU/DSU Channel Service Unit/Data Service Unit Figure 14.7