| A | B |
|---|
| Routers | LAN and WAN interface ports |
| Switches | Connect to WAN bandwidth |
| Modems | interface with voice grade services |
| Communication servers | dail-in and dail-out users |
| HDLC | High-level Data Link Control |
| Frame Relay | Simplified Framing |
| PPP | Point-to-point Protocol |
| SDLC | Synchronous Data link Control Protocol |
| SLIP | Serial Line Interface Protocol |
| LAPB | Link Access Procedure Balanced |
| LAPD | Link Access Procedure D Channel |
| LAPF | Link Access Procedure Frame |
| POTS | Plain Old Telephone Service |
| Narrowband ISDN | Narrowband Intergrated Services Digital Network |
| X.25 | Old Technology |
| ATM | Asynchrronous Transfer Mode |
| SMDS | Switched Multimegabit Data Service |
| T1 | 1.544 Mbps |
| T3 | 44.736 Mbps |
| E1 | 2.048 Mbps |
| E3 | 34.368 Mbps |
| xDSL | digital subscriber line |
| HDSL | High bit-rate DSL |
| SDSL | Single- line DSL |
| ADSL | Asymmetric DSL |
| VDSL | Very high bit rate DSL |
| RADSL | Rate adaptive DSL |
| SONET | Synchronous Optical network |
| Dialup Modems | limited but versatile |
| Cable Modems | daat signals on same cable as television |
| Wireless | No mediun |
| Satellite | serves mobile users |
| RAM/DRAM | Stores routing tables , ARP cache |
| NVRAM | Nonvolatile RAM |
| Flash memory | erasable,reprogrammable ROM |
| ROM | bootstrap program |
| Interface | connection which packets enter and exit |
| Internal routers | stay internal to one area |
| area borders routers | connect two or more areas |
| backbone routers | serve as primary paths for traffic |
