CH5

This sublayer communicates directly with the physical layer.

MAC sublayer (Media Access Control)

Notifies destinations to get ready for a new frame

Preamble

Dropped frames are likely to be the result of?

collisions or other unwanted signals and are therefore considered invalid.

LAN and WAN topologies can be physical or logical. It is the _____ topology that influences the type of network framing and media access control used.

logical

The physical layer standards address three functional areas:

physical components, frame encoding technique, and signaling method.

LLC is implemented in ______, and its implementation is independent of the hardware.

software

Today's Ethernet LANs use full-duplex _____ , which allow multiple devices to send and receive simultaneously with no collisions.

switches They use switches now, not really Hubs anymore

What can be considered the driver software for a NIC?

the LLC (in the data link sublayer)

Any frame less than 64 bytes in length is considered a ________ or_______ and is automatically discarded by receiving stations.

"collision fragment" "runt frame"

Frames with more than 1500 bytes of data are considered ______ or ________ ______ ______.

"jumbo" "baby giant frames".

Ethernet standards define both the Layer___ protocols and the Layer ___ technologies.

2 1 the basic frame format and address scheme is the same for all varieties of Ethernet.

The minimum Ethernet frame size is____ bytes and the maximum is _____ bytes.

64 1518 This includes all bytes from the Destination MAC Address field through the Frame Check Sequence (FCS) field. The Preamble field is not included when describing the size of a frame.

Ethernet operates in the data link layer and the physical layer. It is a family of networking technologies that are defined in the IEEE ______ and _____ standards.

802.2 (LLC) 802.3 (MAC)

Uses Pad to increase this frame field to at least 64 bytes?

802.2 Header and Data

the Ethernet MAC sublayer has two primary responsibilities:

Data encapsulation: Frame assembly/disassembly (adding headers & trailers [delimiting bits]) Media access control: places frames onto media and removes when needed. Controls access to media

Assists a host in determining if the frame received is addressed to it?

Destination address

These standards define both the Layer 2 protocols and the Layer 1 technologies.

Ethernet

______ is now the predominant LAN technology in the world. What two layers does it operate?

Ethernet Ethernet operates in the data link layer and the physical layer.

_______ __ is the Ethernet frame format used in TCP/IP networks.

Ethernet II

Describes which higher-layer protocol has been used?

Frame Type

Detects errors in an Ethernet frame

Frame check Sequence

Data encapsulation from MAC sublayer provides three primary functions:

Frame delimiting: adds delimiting bits that Identify bits that make up a frame and provide synchronization between transmitting and receiving nodes. Addressing - The encapsulation process contains the Layer 3 PDU and also provides for data link layer addressing. Error detection - Each frame contains a trailer used to detect any errors in transmissions.

Which Datalink sublayer controls the network interface card through software drivers?

LLC

Which Datalink sublayer remains relatively independent of physical equipment?

LLC

Which Datalink sublayer works with the upper layers to add application information for delivery of data to higher level protocols?

LLC

In the Ethernet data link sublayer, ______ is software drivers for the NIC while _____ is implemented by the hardware?

LLC MAC

The Ethernet ____ sublayer handles the communication between the upper layers and the lower layers.

LLC: looks up and transitions down between the networking software and the device hardware.

Which Datalink sublayer controls access to the media through signaling and physical media standard requirements?

MAC

Which Datalink sublayer supports Ethernet technology by using CSMA/CD or CSMA/CA?

MAC

Which Datalink sublayer works with hardware to support bandwidth requirements and checks errors in the bits sent and received?

MAC

____ constitutes the lower sublayer of the data link layer.

MAC

what interacts directly with the hardware on the NIC to pass the data between the MAC sublayer and the physical media.

NIC driver (LLC)

Explain the Ethernet III frame field?

Preamble: These first eight bytes of the frame are used to get the attention of the receiving nodes. Essentially, the first few bytes tell the receivers to get ready to receive a new frame. Destination MAC address: this address is used by Layer 2 to assist devices in determining if a frame is addressed to them. Sources MAC address: Identifies the frames originating NIC or interface. Must be a Unicast address. EtherType: Identifies upper layer protocol encapsulated in the frame. Data: an Ipv4 packet that has been encapsulated. Must be at least 64 bits long. FCS: Frame Check Sequence, used to detect errors. Uses CRC

The ______ field is not included when describing the size of a frame.

Preamble: are used for synchronization between the sending and receiving devices. These first eight bytes of the frame are used to get the attention of the receiving nodes. Essentially, the first few bytes tell the receivers to get ready to receive a new frame.

The frames originating NIC or interface MAC address is called?

Source address

Synchronizes sending and receiving devices for frame delivery.

Start of Frame Delimiter

The_____ network access layer is the equivalent of the OSI data link layer (Layer 2) and the physical layer (Layer 1).

TCP/IP

How does the LLC sublayer in data link (Ethernet) sublayer help deliver a packet?

Takes the network protocol data which is typically an IPv4 packet, and adds control information

All frames must be at least 64 bytes long. If a small packet is encapsulated, what happens?

additional bits called a pad are used to increase the size of the frame to this minimum size.

The underlying logical topology of Ethernet is a multi-access bus which means what?

all nodes (devices) on a network share the medium (bus). Contention-based

A contention-based method means that?

any device can try to transmit data across the shared medium whenever it has data to send.

Explain what CRC is?

cyclic redundancy check (CRC). The sending device includes the results of a CRC in the FCS field of the frame. The receiving device receives the frame and generates a CRC to look for errors. If the calculations match, no error occurred. Calculations that do not match are an indication that the data has changed; therefore, the frame is dropped.

If the size of a transmitted frame is less than the minimum or greater than the maximum, the receiving device does what?

drops the frame

The use of _____ aids in the transmission of bits as they are placed on the media and in the grouping of bits at the receiving node.

frames

At the data link layer, the frame structure is nearly ____ for all speeds of Ethernet.

identical

media access control techniques define:

if and how the nodes share the media. The actual media access control method used depends on the topology and media sharing