Ethernet. Network Fundamentals – Chapter 9 Sandra Coleman, CCNA, CCAI. Objectives. Identify the basic characteristics of network media used in Ethernet. Describe the physical and data link features of Ethernet.
Network Fundamentals – Chapter 9
Sandra Coleman, CCNA, CCAI
Identify the basic characteristics of network media used in Ethernet.
Describe the physical and data link features of Ethernet.
Describe the function and characteristics of the media access control method used by Ethernet protocol.
Explain the importance of Layer 2 addressing used for data transmission and determine how the different types of addressing impacts network operation and performance.
Compare and contrast the application and benefits of using Ethernet switches in a LAN as opposed to using hubs.
Explain the ARP process.
DIX (Digital Equipment, Intel, Xerox) – released stds. in 1980
IEEE 802.x – 1985
Ethernet operates at Layers 1 & 2 of OSI Model (Physical & Data Link)
Ethernet operates at Network Access layer of TCP/IP model
Alohanet – 1970 – digital radio network to connect Hawaiin islands.
1st LAN – Robert Metcalf – Xerox – 30 yrs. Ago
LLC sublayer – (802.2) independent of physical equip. Concerned with upper layer transitions
Layer 1 – involves signals, bit streams that travel on the media, various topologies
Layer 2 – MAC sublayer – concerned w/physical components (802.3)
Know the IEEE numbers for Layer 1 & 2 protocols
Logic Link Control – Connecting the Upper Layers
IEEE 802.2 standard is represented here
Media Access Control (MAC)
2 most common types of media are copper UTP and optical fiber.
DATA field contains the layer 3 (network layer) packet
Copied to RAM from ROM during POST (startup)
6 bytes (12 hex digits) long (3 bytes OUI, 3 bytes vendor assigned)
Base 16 – 0-9, A-F..
MAC – used locally in the frame, layer 2 address
IP – used to cross a WAN in a packet, layer 3 address
IP addresses NEVER change in a packet (layer 3)
MAC addresses DO change within a frame (layer 2)
If a device doesn’t know the MAC address for an IP address, it will broadcast an ARP request for this information.
Broadcast – delivers a packet to all hosts on a single broadcast domain
Multicast – delivers a packet to a group of hosts
All devices have guaranteed access to the medium, but no prioritized claim on it. Explain CSMA/CD.
Gives the media time to stabilize between frames. Allows slow devices time to process a frame and prepare for the next frame.
All devices are required to wait 96 microseconds before transmitting again.
Receiving device responds by sending an ARP reply back as a unicast frame with its MAC address. It can then be added to the ARP table.
Purpose: resolve IPv4 addresses to MAC addresses
Maintained dynamically by monitoring traffic that occurs on that segment of the network or by broadcasting an ARP request packets with the desired IP address, looking for the MAC address.