Cisco Networking Chap 5: Ethernet

Front 1

What layers of the OSI model does Ethernet operate?

Back 1

data link layer

physical layer

Front 2

LLC sublayer

Back 2

Handles communication between upper and lower layers. Typically between network software and device hardware.

Front 3

What does the LLC sublayer do to the network protocol data which is typically an IPv4 packet?

Back 3

Adds control information to help deliver the packet to destination node.

Front 4

MAC sublayer

Back 4

Implemented by hardware, typically in the computer's NIC.

Front 5

Data encapsulation

Back 5

MAC layer process which includes frame assembly and disassembly. When forming a frame, it adds trailer and header information to the PDU.

Front 6

3 primary processes of Data Encapsulation

Back 6

Frame delimiting

Addressing

Error detection

Front 7

Frame delimiting

Back 7

Provides delimiters used to identify a group of bits that make up a frame. Provides synchronization between the transmitting and receiving nodes.

Front 8

Addressing

Back 8

Adds the physical MAC address to the ethernet header on a frame.

Front 9

Error detection

Back 9

Adds a trailer with a Cyclic Redundancy Check (CRC) of frame contents. When node receives packet, it creates another CRC and checks the frame's CRC for an identical match to know the frame is not corrupted.

Front 10

Media Access Control

Back 10

2nd Responsibility of MAC sublayer. Controls placement and removal of frames on the media. Communicates directly with Physical layer.

Front 11

The primary fields in the Ethernet frame are?

Back 11

Preamble and Start Frame Delimiter Fields
Destination MAC Address
Source MAC Address
Length
Data
Frame Check Sequence

Front 12

Preamble and Start Frame Delimiter Fields

Back 12

The Preamble (7 bytes) and Start Frame Delimiter (SFD) (1 byte), fields are used for synchronization between sending/receiving devices

Front 13

Destination MAC Address Field

Back 13

6-bye field identifying the recipient. Used by Layer 2 to determine if the frame was intended for the device by matching the device MAC address and the one in the frame.

Front 14

Source MAC Address Field

Back 14

6-byte field identifying the source device.

Front 15

Length Field

Back 15

Used by the Frame Check Sequence (FCS) field to ensure proper frame delivery. Also identifies which higher layer protocol is present.

Front 16

Data Field

Back 16

46-1500 Bytes, contains encapsulated data from the upper Layer 3 PDU or IPv4 packet.

Front 17

Frame Check Sequence Field

Back 17

Detects errors in the frame using CRC. Source node includes the results of a CRC in this field while the destination node checks this with their own CRC to identify any errors.

Front 18

Fast-forward switching

Back 18

Cut-Through switching variant. Lowest level of latency. Immediately forwards packet after reading the destination address.

Front 19

Fragment-free switching

Back 19

Cut-Through switching variant. Stores the first 64 bytes of the frame to error-check before forwarding. Slightly increases latency but reduces forwarding of corrupt packets, so it can be seen as a compromise between Store-and-Forward and Fast-Forward.

Front 20

Port-based Memory Buffering

Back 20

Frames are stored in queues linked to specific incoming and outgoing ports. They forward only when the entire packet is received.

Front 21

Shared memory Buffering

Back 21

Frames are stored in a common memory buffer, which all ports share. Allows different incoming and outgoing ports for a frame.

Front 22

Fixed Configuration Switches

Back 22

Switch with unmodifiable features (eg. fixed amount of ports)

Front 23

Modular Switches

Back 23

Switch with modifiable features, typically with larger chassis to support additional line cards with more ports.

Front 24

Switch Virtual Interface (SVI)

Back 24

Logical interface on a switch indicating a virtual local area network (VLAN)

Front 25

Routed Port

Back 25

Physical port on a Layer 3 switch configured to act as a router port.

Front 26

Layer 3 Ether Channel

Back 26

Logical interface on a Cisco device associated with a bundle of routed ports.

Front 27

Which destination address is used in an ARP request frame?

Back 27

FFFF.FFFF.FFFF

Front 28

What sub layer is responsible for communicating directly with the physical layer.

Back 28

MAC

Front 29

What is a characteristic of a contention-based access method?

Back 29

It is a nondeterministic method.

Front 30

A collision fragment, with less than 64 bytes in the frame

Back 30

runt frame

Front 31

Which two functions or operations are performed by the MAC sublayer?

Back 31

It is responsible for Media Access Control.

It adds a header and trailer to form an OSI Layer 2 PDU.

Front 32

What type of address is 01-00-5E-0A-00-02?

Back 32

a MAC address that reaches a specific group of hosts.

The multicast MAC address is a special value that begins with 01-00-5E in hexadecimal. It allows a source device to send a packet to a group of devices.

Front 33

Which term defines the processing capabilities of a switch by rating how much data can be processed per second?

Back 33

Forwarding Rate

Front 34

What is a characteristic of a contention-based access method?

Back 34

It is a nondeterministic method.

Front 35

What describes features or functions of the logical link control sublayer in Ethernet standards?

Back 35

The data link layer uses LLC to communicate with the upper layers of the protocol suite.

Logical link control is implemented in software.

Front 36

What is the purpose of the preamble in an Ethernet frame?

Back 36

is used for timing synchronization

Front 37

When would a switch record multiple entries for a single switch port in its MAC address table?

Back 37

when another switch is connected to the switch port

Front 38

The binary number 0000 1010 can be expressed as what in hexadecimal?

Back 38

0A

Front 39

IPv4 Multi-cast Address range

Back 39

224.0.0.0 to 239.255.255.255

Front 40

Store and Forward switching

Back 40

Switch process where a packet is stored until the complete frame is received. It deletes the packets with errors to minimize bandwidth usage. It forwards the packets when the complete frame is received.

Front 41

Cut-Through Switching

Back 41

Switch process where a packet is immediately forwarded without error-checking. Corrupt packets are still forwarded and can take up bandwidth as a result. Two variants include: Fast-Forward and Fragment-Free.

Front 42

Difference between Layer 2 and Layer 3 Switch

Back 42

Layer 3 Switches can forward traffic based on IP as well as MAC address information, unlike a Layer 2 switch. They can also perform Layer 3 routing functions which reduce the need for dedicated routers.