Module 6 Quizlet
Ethernet Frame Fields The format for Ethernet frames specifies the location of the destination and source MAC addresses, and additional information including:
- Preamble for sequencing and timing - Start of frame delimiter - Length and type of frame - Frame check sequence to detect transmission errors
When an Ethernet switch receives a frame that is broadcast, it will: 1. Forward the frame out all ports except the incoming port 2. Forward the frame out all ports including the incoming port 3. Forward the frame out only ports that need the broadcast 4. Drop the frame
1. Forward the frame out all ports except the incoming port
Host-A sends an ARP request and receives an ARP reply from Host-B. What is in the ARP reply that Host-A did not know and needs to communicate with Host-B? 1. Host B's MAC address 2. Host B's IP address 3. Host B's IP and MAC addresses
1. Host B's MAC address
Refer to the exhibit. How is a frame sent from PCA forwarded to PCC if the MAC address table on switch SW1 is empty? 1. SW1 floods the frame on all ports on SW1, excluding the port through which the frame entered the switch. 2. SW1 floods the frame on all ports on the switch, excluding the interconnected port to switch SW2 and the port through which the frame entered the switch. 3. SW1 drops the frame because it does not know the destination MAC address. 4. SW1 forwards the frame directly to SW2. SW2 floods the frame to all ports connected to SW2, excluding the port through which the frame entered the switch.
1. SW1 floods the frame on all ports on SW1, excluding the port through which the frame entered the switch.
Host-B receives an ARP request. Host-B will return an ARP Reply if: 1. The IP address in the ARP request matches its own IP address. 2. The MAC address in the ARP request matches its own MAC address. 3. The IP and MAC addresses in the ARP request matches its own IP and MAC addresses.
1. The IP address in the ARP request matches its own IP address.
When an Ethernet frame is sent out an interface, the destination MAC address indicates: 1. The MAC address of the device, which is on this network, that will receive the Ethernet frame. 2. The MAC address of the NIC card of a device, which is on this network or another network, that will receive the Ethernet frame. 3. The MAC address of the NIC card that sent the Ethernet frame. 4. The MAC address of the router.
1. The MAC address of the device, which is on this network, that will receive the Ethernet frame.
ARP uses a three step process to discover and store the MAC address of a host on the local network when only the IPv4 address of the host is known:
1. The sending host creates and sends a frame addressed to a broadcast MAC address. Contained in the frame is a message with the IPv4 address of the intended destination host. 2. Each host on the network receives the broadcast frame and compares the IPv4 address inside the message with its configured IPv4 address. The host with the matching IPv4 address sends its MAC address back to the original sending host. 3. The sending host receives the message and stores the MAC address and IPv4 address information in a table called an ARP table.
Which three fields are found in an 802.3 Ethernet frame? (Choose three.) 1. frame check sequence 2. destination logical address 3. source logical address 4. destination physical address 5. source physical address 6. media type identifier
1. frame check sequence, 4. destination physical address, & 5. source physical address
An Ethernet MAC address is considered what type of address: 1. physical 2. logical
1. physical
Which address does not change when a device is connected to a new network? 1. physical 2. logical
1. physical
Which network device has the primary function to send data to a specific destination based on the information found in the MAC address table? 1. switch 2. modem 3. router 4. hub
1. switch
What is the purpose of ARP in an IPv4 network? 1. to obtain a specific MAC address when an IP address is known 2. to forward data onward based on the destination MAC address. 3. to forward data onward based on the destination IP address 4. to build the MAC address table in a switch from the information that is gathered
1. to obtain a specific MAC address when an IP address is known
The size of Ethernet frames is normally limited to a maximum of ____ _____ from the Destination MAC Address field through the Frame Check Sequence (FCS).
1518 bytes
Host-A has an Ethernet frame to send to Host-B on the same network. Host-A knows the IP address of Host-B but not its MAC address. What message will Host-A send to determine the MAC address of Host B? 1. ARP discovery 2. ARP request 3. ARP reply 4. ARP broadcast
2. ARP request
Which statement is true about broadcast and collision domains? 1. The more interfaces a router has the larger the resulting broadcast domain. 2. Adding a switch to a network will increase the size of the broadcast domain. 3. Adding a router to a network will increase the size of the collision domain. 4. The size of the collision domain can be reduced by adding hubs to a network.
2. Adding a switch to a network will increase the size of the broadcast domain.
Ethernet switches make their forwarding decision based on what field of the Ethernet frame? 1. SFD (Start Frame Delimiter) 2. Destination MAC address 3. Source MAC address 4. Type/Length 5. FCS
2. Destination MAC address
The Ethernet protocol is at what layer of the OSI Model? 1. Layer 1 Physical 2. Layer 2 Data Link 3. Layer 3 Network 4. Layer 4 Transport
2. Layer 2 Data Link
The process of prepending protocol information with information from another protocol is called: 1. framing 2. encapsulation 3. encoding 4. packetizing
2. encapsulation
An IP address is considered what type of address: 1. physical 2. logical
2. logical
Ethernet hubs are considered: 1. cutting-edge 2. obsolete 3. a security device 4. a wireless device
2. obsolete
When a switch receives an Ethernet frame and the destination MAC address of that frame is not in its MAC address table, the switch will: 1. Add the Destination MAC address to the table. 2. Add the Source MAC address to the table. 3. Forward the frame out all ports except in the incoming port. 4. Drop the frame.
3. Forward the frame out all ports except in the incoming port.
Which two devices would commonly be found at the access layer of the hierarchical enterprise LAN design model? (Choose two.) 1. Layer 3 device 2. Modular switch 3. Layer 2 switch 4. Firewall 5. Access point
3. Layer 2 switch & 5. Access point
Which network device can serve as a boundary to divide a Layer 2 broadcast domain? 1. Ethernet bridge 2. Access point 3. Router 4. Ethernet hub
3. Router
Ethernet switches add entries to their MAC address table based on what field of the Ethernet frame? 1. SFD (Start Frame Delimiter) 2. Destination MAC address 3. Source MAC address 4. Type/Length 5. FCS
3. Source MAC address
Which design layer provides connectivity to devices on an Ethernet LAN? 1. core 2. distribution 3. access 4. physical
3. access
Which term refers to the process of placing one message format inside another message format? 1. segmenting 2. manipulation 3. encapsulation 4. encoding
3. encapsulation
What information does an Ethernet switch examine and use to build its address table? 1. source IP address 2. destination MAC address 3. source MAC address 4. destination IP address
3. source MAC address
The destination MAC address of an Ethernet broadcast in hexadecimal is: 1. 48 one bits 2. 48 F digits 3. 1111.1111.1111 4. FFFF.FFFF.FFFF
4. FFFF.FFFF.FFFF
Which Ethernet frame field indicates the beginning of an Ethernet frame? 1. Type/Length 2. Destination MAC Address 3. FCS 4. Preamble and SFD
4. Preamble and SFD
What is the purpose of the core layer in the Cisco hierarchical network design model? 1. network access to end devices 2. flow control between networks 3. aggregation point for smaller networks 4. high-speed backbone switching
4. high-speed backbone switching
Which portion of an IP address uniquely identifies that device on that network? 1. physical 2. logical 3. network 4. host
4. host
Which destination address is used in an ARP request frame? 1. The physical address of the destination host 2. 255.255.255.255 3. AAAA.AAAA.AAAA 4. 0.0.0.0 5. FFFF.FFFF.FFFF
5. FFFF.FFFF.FFFF
The size of Ethernet frames is normally limited to a minimum size of __ _____ from the Destination MAC Address field through the Frame Check Sequence (FCS).
64 bytes
Analogy
A common example of requiring the correct format in human communications is when sending a letter. Click Play in the figure to view an animation of formatting and encapsulating a letter. An envelope has the address of the sender and receiver, each located at the proper place on the envelope. If the destination address and formatting are not correct, the letter is not delivered. The process of placing one message format (the letter) inside another message format (the envelope) is called encapsulation. De-encapsulation occurs when the process is reversed by the recipient and the letter is removed from the envelope.
Physical and Logical Addresses
A person's name usually does not change. A person's address on the other hand, relates to where the person lives and can change. On a host, the MAC address does not change; it is physically assigned to the host NIC and is known as the physical address. The physical address remains the same regardless of where the host is placed on the network.
MAC address table
A table on the switch, called a ___ _______ _____, contains a list of all of the active ports and the host MAC addresses that are attached to them. When a message is sent between hosts, the switch checks to see if the destination MAC address is in the table. If it is, the switch builds a temporary connection, called a circuit, between the source and destination ports. This new circuit provides a dedicated channel over which the two hosts can communicate. Other hosts attached to the switch do not share bandwidth on this channel and do not receive messages that are not addressed to them. A new circuit is built for every new conversation between hosts. These separate circuits allow many conversations to take place at the same time, without collisions occurring. Ethernet switches also allow for the sending and receiving of frames over the same Ethernet cable simultaneously. This improves the performance of the network by eliminating collisions.
As shown in the figure, the hierarchical design has three basic layers:
Access Layer, Distribution Layer, & Core Layer
Ethernet Switches
An Ethernet switch is a device that is used at the access layer. When a host sends a message to another host connected to the same switched network, the switch accepts and decodes the frames to read the physical (MAC) address portion of the message.
Only one message can be sent through an Ethernet hub at a time. It is possible for two or more hosts connected to a hub to attempt to send a message at the same time. If this happens, the electronic signals that make up the messages collide with each other at the hub. This is known as a collision. The message is unreadable by hosts and must be retransmitted. The area of the network where a host can receive a garbled message resulting from a collision is known as a collision domain.
Because excessive retransmissions can clog up the network and slow down network traffic, hubs are now considered obsolete and have been replaced by Ethernet switches.
What Did I Learn in this Module?
Encapsulation and the Ethernet Frame The process of placing one message format (such as a letter) inside another message format (such as an envelope) is called encapsulation. Each computer message is encapsulated in a specific format, called a frame, before it is sent over the network. A frame acts like an envelope; it provides the address of the intended destination and the address of the source host. The format and contents of a frame are determined by the type of message being sent and the channel over which it is communicated. The Ethernet protocol standards define many aspects of network communication including frame format, frame size, timing, and encoding. When messages are sent between hosts on an Ethernet network, the hosts format the messages into the frame layout that is specified by the standards. Frames are also referred to as Layer 2 protocol data units (PDUs). This is because the protocols that provide the rules for the creation and format of the frame perform the functions that are specified at the data link layer (Layer 2) of the OSI model. Hierarchical Network Design IP addresses contain two parts. One part identifies the local network. This portion of the IP address will be the same for all hosts connected to the same local network. The second part of the IP address identifies the individual host. Both the physical MAC and logical IP addresses are required for a computer to communicate on a hierarchical network, just like both the name and address of a person are required to send a letter. Large Ethernet networks consisting of many hosts need to be divided into smaller, more manageable pieces. One way to divide larger networks is to use a hierarchical design model. The hierarchical design has three basic layers: Access Layer - This layer provides connections to hosts in a local Ethernet network. Distribution Layer - This layer interconnects the smaller local networks. Core Layer - This layer provides a high-speed connection between distribution layer devices. With a hierarchical design, you need a logical addressing scheme that can identify the location of a host. The most common addressing scheme used on company networks is Internet Protocol version 4 (IPv4). Internet Protocol version 6 (IPv6) is the network layer protocol currently being implemented as a replacement to IPv4. The Access Layer The access layer is the part of the network in which people gain access to other hosts and to shared files and printers. The access layer provides the first line of networking devices that connect hosts to the wired Ethernet network. There are several types of networking devices that can be used to connect hosts at the access layer, including Ethernet hubs and switches. Ethernet hubs contain multiple ports that are used to connect hosts to the network. Hubs cannot decode the messages sent between hosts on the network. Hubs cannot determine which host should get any particular message. A hub simply accepts electronic signals from one port and regenerates (or repeats) the same message out all of the other ports. All hosts attached to the hub share the bandwidth, and will receive the message. Hosts ignore the messages that are not addressed to them. Only the host specified in the destination address of the message processes the message and responds to the sender. If a switch is being used and the destination MAC address is not in the MAC address table, the switch cannot determine where the destination host is located. The switch then uses a process called flooding to forward the message out to all attached hosts except for the sending host. How does the MAC address of a new host get into the MAC address table? A switch builds the MAC address table by examining the source MAC address of each frame that is sent between hosts. When a new host sends a message or responds to a flooded message, the switch immediately learns its MAC address and the port to which it is connected. The table is dynamically updated each time a new source MAC address is read by the switch. Broadcast Containment Within the local network a host may need to send messages to all the other hosts at the same time. This can be done using a broadcast message. Broadcast messages are sent to a unique MAC address that is recognized by all hosts. The broadcast MAC address is actually a 48-bit address made up of all ones. When a host receives a message addressed to the broadcast address, it accepts and processes the message as though the message was addressed directly to it. When a host sends a broadcast message, switches forward the message to every connected host within the same local network. For this reason, a LAN is also referred to as a broadcast domain. Routers are used to divide the network into multiple broadcast domains. How does the sending host determine what destination MAC address to place within the frame? The sending host can use an IPv4 protocol called ARP to discover the MAC address of any host on the same local network. IPv6 uses a similar method known as Neighbor Discovery. ARP uses a three step process to discover and store the MAC address of a host on the local network when only the IPv4 address of the host is known: The sending host creates and sends a frame addressed to a broadcast MAC address. Contained in the frame is a message with the IPv4 address of the intended destination host. Each host on the network receives the broadcast frame and compares the IPv4 address inside the message with its configured IPv4 address. The host with the matching IPv4 address sends its MAC address back to the original sending host. The sending host receives the message and stores the MAC address and IPv4 address information in a table called an ARP table.
The __ _______ is similar to the address of a person. It is known as a logical address because it is assigned logically based on where the host is located. The __ _______, or network address, is assigned to each host by a network administrator based on the local network.
IP address
Access, Distribution, and Core
IP traffic is managed based on the characteristics and devices associated with each of the three layers of the hierarchical network design model: Access, Distribution and Core.
Hierarchical Analogy
Imagine how difficult communication would be if the only way to send a message to someone was to use the person's name. If there were no street addresses, cities, towns, or country boundaries, delivering a message to a specific person across the world would be nearly impossible.
Benefits of a Hierarchical Design
In networking, hierarchical design is used to group devices into multiple networks that are organized in a layered approach. This method of designing networks consists of smaller, more manageable groups that allow local traffic to remain local. Only traffic that is destined for other networks is moved to a higher layer. A hierarchical, layered design provides increased efficiency, optimization of function, and increased speed. It allows the network to scale as required because additional local networks can be added without impacting the performance of the existing ones.
With a hierarchical design, there is a need for a logical addressing scheme that can identify the location of a host. The most common addressing scheme on the internet is ________ ________ _______ _(IPv4). Internet Protocol version 6 (IPv6) is the network layer protocol currently being implemented as a replacement for IPv4. IPv4 and IPv6 will coexist for the foreseeable future. From this point on in this course, the term IP will refer to both IPv4 and IPv6. ________ ________ _______ _
Internet Protocol version 4 & Internet Protocol version 6
Access Layer Communication
On a local Ethernet network, a NIC only accepts a frame if the destination address is either the broadcast MAC address, or else corresponds to the MAC address of the NIC. Most network applications, however, rely on the logical destination IP address to identify the location of the servers and clients. The figure illustrates the problem that arises if a sending host only has the logical IP address of the destination host. How does the sending host determine what destination MAC address to place within the frame? The sending host can use an IPv4 protocol called address resolution protocol (ARP) to discover the MAC address of any host on the same local network. IPv6 uses a similar method known as Neighbor Discovery.
Canada
On an Ethernet network, the host MAC address is similar to a person's name. A MAC address indicates the individual identity of a specific host, but it does not indicate where on the network the host is located. If all hosts on the internet (millions and millions of them) were each identified by their unique MAC address only, imagine how difficult it would be to locate a single one. Additionally, Ethernet technology generates a large amount of broadcast traffic in order for hosts to communicate. Broadcasts are sent to all hosts within a single network. Broadcasts consume bandwidth and slow network performance. What would happen if the millions of hosts attached to the internet were all in one Ethernet network and were using broadcasts? For these two reasons, large Ethernet networks consisting of many hosts are not efficient. It is better to divide larger networks into smaller, more manageable pieces. One way to divide larger networks is to use a hierarchical design model.
Halifax
On an Ethernet network, the host MAC address is similar to a person's name. A MAC address indicates the individual identity of a specific host, but it does not indicate where on the network the host is located. If all hosts on the internet (millions and millions of them) were each identified by their unique MAC address only, imagine how difficult it would be to locate a single one. Additionally, Ethernet technology generates a large amount of broadcast traffic in order for hosts to communicate. Broadcasts are sent to all hosts within a single network. Broadcasts consume bandwidth and slow network performance. What would happen if the millions of hosts attached to the internet were all in one Ethernet network and were using broadcasts? For these two reasons, large Ethernet networks consisting of many hosts are not efficient. It is better to divide larger networks into smaller, more manageable pieces. One way to divide larger networks is to use a hierarchical design model.
North America
On an Ethernet network, the host MAC address is similar to a person's name. A MAC address indicates the individual identity of a specific host, but it does not indicate where on the network the host is located. If all hosts on the internet (millions and millions of them) were each identified by their unique MAC address only, imagine how difficult it would be to locate a single one. Additionally, Ethernet technology generates a large amount of broadcast traffic in order for hosts to communicate. Broadcasts are sent to all hosts within a single network. Broadcasts consume bandwidth and slow network performance. What would happen if the millions of hosts attached to the internet were all in one Ethernet network and were using broadcasts? For these two reasons, large Ethernet networks consisting of many hosts are not efficient. It is better to divide larger networks into smaller, more manageable pieces. One way to divide larger networks is to use a hierarchical design model.
Nova Scotia
On an Ethernet network, the host MAC address is similar to a person's name. A MAC address indicates the individual identity of a specific host, but it does not indicate where on the network the host is located. If all hosts on the internet (millions and millions of them) were each identified by their unique MAC address only, imagine how difficult it would be to locate a single one. Additionally, Ethernet technology generates a large amount of broadcast traffic in order for hosts to communicate. Broadcasts are sent to all hosts within a single network. Broadcasts consume bandwidth and slow network performance. What would happen if the millions of hosts attached to the internet were all in one Ethernet network and were using broadcasts? For these two reasons, large Ethernet networks consisting of many hosts are not efficient. It is better to divide larger networks into smaller, more manageable pieces. One way to divide larger networks is to use a hierarchical design model.
IP addresses contain two parts.
One part identifies the network portion. The network portion of the IP address will be the same for all hosts connected to the same local network. The second part of the IP address identifies the individual host on that network. Within the same local network, the host portion of the IP address is unique to each host, as shown in the figure.
Network
Similar to sending a letter, a message that is sent over a computer network follows specific format rules for it to be delivered and processed. Internet Protocol (IP) is a protocol with a similar function to the envelope example. In the figure, the fields of the Internet Protocol version 6 (IPv6) packet identify the source of the packet and its destination. IP is responsible for sending a message from the message source to destination over one or more networks. (Note: The fields of the IPv6 packet are discussed in detail in another module.)
Access Layer Devices
The access layer is the basic level of the network. It is the part of the network in which people gain access to other hosts and to shared files and printers. The access layer provides the first line of networking devices that connect hosts to the wired Ethernet network.
Ethernet Hubs
The original Ethernet networks connected all hosts with a single cable, similar to how cable TV cables are connected in your home. All users on the network shared the bandwidth available on the cable. As Ethernet networks became more popular, connecting everyone on a single cable was no longer practical, nor even possible. Engineers developed a different type of network technology that made it easier to connect and reconnect multiple devices to the network. The first of these types of networking devices were ________ ____.
Networking devices
This enables us to connect many hosts with each other and also provide those hosts access to services offered over the network. Unlike the simple network consisting of two hosts connected by a single cable, in the access layer, each host is connected to a networking device. This type of connectivity is shown in the figure.
When messages are sent between hosts on an Ethernet network, the hosts format the messages into the frame layout that is specified by the standards. Frames are also referred to as Layer 2 protocol data units (PDUs).
This is because the protocols that provide the rules for the creation and format of the frame perform the functions that are specified at the data link layer (Layer 2) of the OSI model.
Distribution Layer
This layer interconnects the smaller local networks. The distribution layer provides a connection point for separate networks and controls the flow of information between the networks. It typically contains more powerful switches, such as the Cisco C9300 series shown in the figure, than the access layer as well as routers for routing between networks. Distribution layer devices control the type and amount of traffic that flows from the access layer to the core layer.
Core Layer
This layer provides a high-speed connection between distribution layer devices. The core layer is a high-speed backbone layer with redundant (backup) connections. It is responsible for transporting large amounts of data between multiple end networks. Core layer devices typically include very powerful, high-speed switches and routers, such as the Cisco Catalyst 9600 shown in the figure. The main goal of the core layer is to transport data quickly.
Access Layer
This layer provides connections to hosts in a local Ethernet network. The access layer provides a connection point for end user devices to the network and allows multiple hosts to connect to other hosts through a network device, usually a switch, such as the Cisco 2960-XR shown in the figure, or a wireless access point. Typically, all devices within a single access layer will have the same network portion of the IP address. If a message is destined for a local host, based on the network portion of the IP address, the message remains local. If it is destined for a different network, it is passed up to the distribution layer. Switches provide the connection to the distribution layer devices, usually a Layer 3 device such as a router or Layer 3 switch.
A message can only contain one destination MAC address. So, how is it possible for a host to contact every other host on the local network without sending out a separate message to each individual MAC?
To solve this problem, broadcast messages are sent to a unique MAC address that is recognized by all hosts. The broadcast MAC address is actually a 48-bit address made up of all ones. Because of their length, MAC addresses are usually represented in hexadecimal notation. The broadcast MAC address in hexadecimal notation is FFFF.FFFF.FFFF. Each F in the hexadecimal notation represents four ones in the binary address.
The MAC Address Table
What happens when the switch receives a frame addressed to a new host that is not yet in the MAC address table? If the destination MAC address is not in the table, the switch does not have the necessary information to create an individual circuit. When the switch cannot determine where the destination host is located, it uses a process called flooding to forward the message out to all attached hosts except for the sending host. Each host compares the destination MAC address in the message to its own MAC address, but only the host with the correct destination address processes the message and responds to the sender. How does the MAC address of a new host get into the MAC address table? A switch builds the MAC address table by examining the source MAC address of each frame that is sent between hosts. When a new host sends a message or responds to a flooded message, the switch immediately learns its MAC address and the port to which it is connected. The table is dynamically updated each time a new source MAC address is read by the switch. In this way, a switch quickly learns the MAC addresses of all attached hosts.
Broadcast Domains
When a host receives a message addressed to the broadcast address, it accepts and processes the message as though the message was addressed directly to it. When a host sends a broadcast message, switches forward the message to every connected host within the same local network. For this reason, a local area network, a network with one or more Ethernet switches, is also referred to as a. . .
Ethernet Broadcasts in the Local Network
Within the local network it is often necessary for one host to be able to send messages to all the other hosts at the same time. This can be done using a message known as a broadcast. Broadcasts are useful when a host needs to find information without knowing exactly what other host can supply it, or when a host wants to provide information to all other hosts in the same network in a timely manner.
Ethernet network
Within this, each host is able to connect directly to an access layer networking device using an Ethernet cable. These cables are manufactured to meet specific Ethernet standards. Each cable is plugged into a host NIC and then into a port on the networking device. There are several types of networking devices that can be used to connect hosts at the access layer, including Ethernet switches.
Hub(s)
____ contain multiple ports that are used to connect hosts to the network. ____ are simple devices that do not have the necessary electronics to decode the messages sent between hosts on the network. ____ cannot determine which host should get any particular message. A ____ simply accepts electronic signals from one port and regenerates (or repeats) the same message out all of the other ports. All hosts attached to the ____ share the bandwidth, and will receive the message. Hosts ignore the messages that are not addressed to them. Only the host specified in the destination address of the message processes the message and responds to the sender.
The preamble and the Start of Frame Delimiter (SFD) are used to indicate the. . .
beginning of the frame
If too many hosts are connected to the same broadcast domain, . . .
broadcast traffic can become excessive.
The preamble and the Start of Frame Delimiter are not used in the. . .
calculation of the frame size
To improve performance, it is often necessary to . . .
divide one local network into multiple networks, or broadcast domains, as shown in the figure. Routers are used to divide the network into multiple broadcast domains.
"When sending a letter, the letter writer uses an accepted format to ensure that the letter is delivered and understood by the recipient." The process of placing one message format (the letter) inside another message format (the envelope) is called _____________. De-_____________ occurs when the process is reversed by the recipient and the letter is removed from the envelope. Just as a letter is _____________ in an envelope for delivery, so computer messages are _____________.
encapsulation/encapsulated
what do routers not do?
forward a message
Each computer message is encapsulated in a specific format, called a _____, before it is sent over the network. A _____ acts like an envelope; it provides the address of the intended destination and the address of the source host. The format and contents of a _____ are determined by the type of message being sent and the channel over which it is communicated. Messages that are not correctly formatted are not successfully delivered to or processed by the destination host.
frame
The Ethernet protocol standards define many aspects of network communication including. . .
frame format, frame size, timing, & encoding
When the sending host has the MAC address of the destination host in its ARP table, . . .
it can send frames directly to the destination without doing an ARP request. Because ARP messages rely on broadcast frames to deliver the requests, all hosts in the local IPv4 network must be in the same broadcast domain.
As the network grows and more hosts are added, . . .
network traffic, including broadcast traffic, increases.
Frames that do not match these limits are. . .
not processed by the receiving hosts
Both the ________ ___ and _______ __ addresses are required for a computer to communicate on a hierarchical network, just like both the name and address of a person are required to send a letter.
physical MAC & logical IP
"When sending a letter, the letter writer uses an accepted format to ensure that the letter is delivered and understood by the recipient." In the same way, a message that is sent over a computer network follows. . .
specific format rules in order for it to be delivered and processed
In addition to the frame formats, sizes and timing, Ethernet standards define how. . .
the bits making up the frames are encoded onto the channel. Bits are transmitted as either electrical impulses over copper cable or as light impulses over fiber-optic cable
The number of hosts and the amount of network traffic that can be supported on the local network is limited by . . .
the capabilities of the switches used to connect them.
