CCNA Chapter 6
Cards (12)
- Data Link Layer. It allows upper layer protocols to access the physical layer media and encapsulates Layer 3 packets (IPv4 and IPv6) into Layer 2 Frames.
- The Data Link Layer consists of two sublayers.
- Logical Link Control (LLC)
- Media Access Control (MAC)
- Point-to-point. The simplest and most common WAN topology. Consists of a permanent link between two endpoints.
- Hub and Spoke. Similar to a star topology where a central site interconnects branch sites through point-to-point links.
- Mesh. Provides high availability but requires every end system to be connected to every other end system.
- Bus. All end systems chained together and terminated on each end.
- Ring. Each end system is connected to its respective neighbors to form a ring.
- Half-duplex communication. Only allows one device to send or receive at a time on a shared medium.
- Full-duplex communication. Allows both devices to simultaneously transmit and receive on a shared medium.
- Contention-based access. All nodes operating in half-duplex, competing for use of the medium.
- Controlled access. Deterministic access where each node has its own time on the medium.
- A data link frame has three parts:HeaderDataTrailer