Module 4-7 Netacad

Each IPV4 address contains a string of 32 bits divided into 4 sections called octets.

How are IPv4 addresses formed

8 bits

Octet to Bits

8 hextets, or 8*16 bits

IPv6 Length in Bits

Counting starts after the value 10, where 11 is A, 12 is B, etc., with each letter represented by 4 bits.

Hexadecimal Counting Explain

Data Link Layer

Prepares network data for the physical network and includes the Network Interface Card (NIC).

Layer 3 Packets

Accepted by the Data Link Layer and encapsulated into Layer 2 frames.

Error Detection

Performed by the Data Link Layer to reject corrupted frames.

Data Link Sublayers

Includes IEEE 802 LAN/MAN and Logical Link Control (LLC).

Logical Link Control (LLC)

Communicates with networking software and device hardware, allowing multiple protocols to use the same interface.

Media Access Control (MAC)

Implements data encapsulation and controls access to the shared medium.

Router

Accepts frames, de-encapsulates them, and re-encapsulates packets into new frames for forwarding.

Hub and Spoke, Mesh, and Point to Point WAN (PPP).

Network Topologies

Half-Duplex

Allows devices to transmit and receive, but not simultaneously.

Full-Duplex

Allows devices to transmit and receive simultaneously.

CSMA/Collision Detection

Checks if any device is transmitting on the medium. If no signal is detected, it proceeds. If a collision is detected (from a higher signal amplitude than normal by the nic), both data would be corrupted and have to be resent.

CSMA/Collision Avoidance

Used on wireless LANs to avoid collisions by waiting before transmitting.

Data Link Frame

Prepares encapsulated data for transport by adding a header and trailer.

Include start/stop indicators, addressing, type, control, data, and error detection.

Packet Frame Fields

Layer 2 Addresses

Physical addresses used in transporting frames, specified in the frame header.

LAN and WAN Frames

Layer 2 protocols work with Layer 3 IP protocols, determined by technology and services.

Minimum size is 64 bytes; frames larger than 1500 bytes are considered jumbo frames.

Ethernet Frame Guidelines

Preamble and SFD

Used for synchronization of receiving/sending devices.

Type/Length

2-byte field identifying the upper layer protocol in the Ethernet frame.

MAC Addresses

Unique identifiers assigned to devices, with the first 6 digits being the OUI.

Unicast MAC Addresses

Used for Layer 2 unicast communication, determined by ARP for IPv4.

Broadcast MAC Address

Flooded to all Ethernet switch ports except the incoming port.

Multicast MAC Address

Used for multicast communication, not forwarded by routers unless configured.

Ethernet Switch

Uses L2 MAC addresses for forwarding decisions and maintains a MAC address table.

Frame Forwarding Methods

Includes store-and-forward and cut-through switching.

Memory Buffering

Used when the destination port is busy, with port-based and shared memory options.

Duplex Mismatch

Occurs when one port operates at half-duplex and another at full-duplex, causing collisions.

Auto MDIX

Switch automatically detects cable type and configures interfaces accordingly.