|  | 6.1 | LAN Standards
| 6.1.1 | Layer 2
Layer 1 involves media, signals, bit streams that travel on media, components that put signals on media, and various topologies. It performs a key role in the communication that takes place between computers, but its efforts, alone, are not enough. Each of its functions has its limitations. Layer 2 addresses these limitations. For each limitation in Layer 1, Layer 2 has a solution. For example, Layer 1 cannot communicate with the upper-level layers; Layer 2 does that with Logical Link Control (LLC). Layer 1 cannot name or identify computers; Layer 2 uses an addressing (or naming) process. Layer 1 can only describe streams of bits; Layer 2 uses framing to organize or group the bits. Layer 1 cannot decide which computer will transmit binary data from a group that are all trying to transmit at the same time. Layer 2 uses a system called Media Access Control (MAC).
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| The Data Link Layer
| Data Link Layer
| CSMC 417
| The Data Link Layer: Protocols