1.2.1 The Rise of Gigabit Ethernet

As LAN traffic increased, Fast Ethernet (100 Mbps) became a bottleneck. 802.3z and 802.3ab introduced Gigabit Ethernet (1000 Mbps).

Study Deep: End of the Shared Medium

The transition from Fast Ethernet to 10GbE marked a fundamental shift in networking:

• CSMA/CD Removal: 10-Gigabit Ethernet (802.3ae) removed half-duplex support entirely. This meant the end of "collisions" in the core.
• Determinism: Without collisions, delay became predictable (deterministic), making Ethernet suitable for industrial and carrier-grade applications.

Key Enhancements:

• Carrier Extension: Used in half-duplex to maintain minimum frame size for collision detection over longer distances.
• Frame Bursting: Allows a station to send a burst of small frames without relinquishing the channel.
• Fiber and Copper: Support for both single-mode/multi-mode fiber and Cat5e+ copper cabling.

1.2.2 10-Gigabit Ethernet and Beyond

10GbE (802.3ae) was a massive leap, primarily focusing on Full-Duplex only operation, effectively ending the era of CSMA/CD in the core network.

• No Collisions: Because it is full-duplex, there is no need for collision detection logic.
• WAN PHY: Allows 10GbE to be directly connected to expensive SONET/SDH optical networks.
• 40GbE / 100GbE: Standards like 802.3ba use multiple lanes of 10G or 25G to reach even higher aggregate speeds.

1.2.3 Fibre Channel (FC)

Fibre Channel is a specialized high-speed network technology primarily used for Storage Area Networks (SANs).

Physical Layer (FC-0 to FC-4):

• FC-0: Physical interface (fiber or copper).
• FC-1: Transmission protocol (encoding/decoding).
• FC-2: Framing protocol (Flow control, Class of service).
• FC-3: Common services (Multicasting).
• FC-4: Upper-layer protocol mapping (SCSI, IP).

1.2.4 Fibre Channel Topologies:

1. Point-to-Point (FC-P2P): Two devices directly connected.
2. Arbitrated Loop (FC-AL): Up to 126 devices in a loop (similar to Token Ring).
3. Switched Fabric (FC-SW): The modern standard, using high-speed switches to allow many-to-many communication.

1.2.5 Comparison: Ethernet vs Fibre Channel