One station transmits at a time
Devices must wait their turn
Provide routes across the internetwork
Format the data for presentation to the user
Facilitate the entry and exit of data on media
Identify the services to which transported data is associated
The logical topology is always the same as the physical topology.
Physical topologies are concerned with how a network transfers frames.
Physical signal paths are defined by Data Link layer protocols.
Logical topologies consist of virtual connections between nodes.
They are 48 binary bits in length.
They are considered physical addresses.
They are generally represented in hexadecimal format.
They consist of four eight-bit octets of binary numbers.
They are used to determine the data path through the network.
They must be changed when an Ethernet device is added or moved within the network.
Source MAC – PC
Source MAC – S0/0 on RouterA
Source MAC – Fa0/1 on RouterB
Source IP – PC
Source IP – S0/0 on RouterA
Source IP – Fa0/1 of RouterB
Network layer addressing
Intermediary device function
Is used as a pad for data
Identifies the source address
Identifies the destination address
Marks the end of timing information
Is used for timing synchronization with alternating patterns of ones and zeros
Layer 2 may identify devices by a physical address burned into the network card
Layer 2 identifies the applications that are communicating
Layer 3 represents a hierarchical addressing scheme
Layer 4 directs communication to the proper destination network
Layer 4 addresses are used by intermediary devices to forward data
Network usage is on a first come, first serve basis.
Computers are allowed to transmit data only when they possess a token.
Data from a host is received by all other hosts.
Electronic tokens are passed sequentially to each other.
Token passing networks have problems with high collision rates.
Ethernet utilizes CSMA/CD
Defined as placement of data frames on the media
Contention-based access is also known as deterministic
802.11 utilizes CSMA/CD
Data Link layer protocols define the rules for access to different media
Controlled access contains data collisions
The nodes are physically connected.
The physical arrangement of the nodes is restricted.
The media access control protocol can be very simple.
The data link layer protocol used over the link requires a large frame header.
The Layer 2 address must be reassigned.
The default gateway address should not be changed.
The device will still operate at the same Layer 2 address.
Applications and services will need additional port numbers assigned.
The Layer 3 address must be reassigned to allow communications to the new network.
Provides the formatting of data
Provides end-to-end delivery of data between hosts
Provides delivery of data between two applications
Provides for the exchange data over a common local media
The Layer 3 protocol selected
The geographic scope of the network
The PDU defined by the transport layer
The physical layer implementation
The number of hosts to be interconnected
Define the logical topology
Provide media access control
Support frame error detection
Carry routing information for the frame
All three networks use CSMA/CA
None of the networks require media access control.
Network 1 uses CSMA/CD and Network 3 uses CSMA/CA.
Network 1 uses CSMA/CA and Network 2 uses CSMA/CD.
Network 2 uses CSMA/CA and Network 3 uses CSMA/CD.
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