Chapters 13 and 15 Flashcards
Role and Purpose of Data Link Layer:
Protocols in the data link layer specify communication over a single network
More precisely, how neighboring computers on the same network send and receive data
Network Protocol Specifications for the Data Link Layer Include:
Packet switching
Hardware addressing using MAC addresses
Method of access to the transmission medium (wire or air)
What is the max size of a packet that the network supports?
LAN
Local Area network, spans room or building
WAN
Wide Area Network:: spans sites in multiple cities
Multi-access networks
organized in a way such that multiple computers share the same medium
LANs are these
Bus Topology
all computes attach to a single cable
Ring Topology
computers are connected in a closed loop
Star Topology
computers connect to a central “hub”
Mesh Topology
direct cable between any two computers (rare)
MAC Address (also called hardware address)
In order for packets to reach the correct recipient, each computer must have a unique identifier
Network Interface Card (NIC)
(I/O) device that allows for a computer to be connected to a network
T or F: hardware (MAC) addresses are used only on the local network (LAN) by the data link (network) layer protocols
True
MAC addressed are used to route packets within a…
LAN
IP addresses are used to route packets across…
different networks (on the internet)
of bits for a MAC address
48 bits and is commonly written using hexadecimal values
EX) 78:2b:cb:b6:79:20
of bits for a IPv4 address
32 bits and is commonly written using decimal values (0-255)
EX) 147.53.55.223
of bits for a IPv6 addresses
126 bits = 16 bytes
Packet Switching vs Circuit Switching
Packet switching: no dedicated line and can be asynchronous
Circuit Switching: must establish a dedicated line and communicates synchronously (must be on at the same time)
Unicast
uniquely identifies destination on computer
Multicast
subset of computers on LAN to receive frame
Broadcast
all computers on LAN are to receive the frame
Frame
Data Link Layer Header + Payload
basic transmission unit at the data link layer
MAC addresses are used…
within a LAN
IP addresses are used…
across LANs
promiscuous mode
allows a station to receive all frames regardless of address
