CNIT 344: The Ethernet Family

T/F: The Ethernet protocol defines the frame format

True

What is the Ethernet Frame format?

Minimum size is 64 bytes, maximum size is 1518 bytes

T/F: If the frame is less than minimum or greater than maximum, processes will resume as normal

False, it’s considered corrupt and will be dropped

What are the first 8 bytes of a packet called?

Preamble (7) and Start of Frame Delimiter (SFD, 1)

What is used to synchronize the NIC with the media in preparation for receiving a frame?

The Preamble and SFD

T/F: The Preamble and SFD are considered part of the frame length and will appear in any capture of the frame

False

What is the order in which a packet is formed?

Preamble (7), SFD (1), Destination MAC (6), Source MAC (6), Length or Type (2), Data and Pad (46-1500), FCS (4)

What is the Destination Mac Address?

Identifies the node that is to receive the frame by comparing the MAC addresses to see if they match

What is the Source Mac Address?

Identifies the node that originated the frame

_______ is the frame type used in TCP/IP networks

Ethernet II

What is the data and pad in the packet?

The encapsulated data from layer 3

T/F: The Data and Pad is most commonly an IPv6 packet

False

What is the Frame Check Sequence (FCS)?

Used to detect errors in a frame that may have occured during transmission along the media

The result of a CRC is placed in the frame by the ______ node

sending

The _________ node performs the same CRC and compares the values, which should be equal if transmission went smoothly

receiving

Ethernet operates with a clock rate of _______

20 MHz

T/F: Ethernet only defines the physical layer, not the connections to use (i.e. cable specs)

False

What is the advantage of frame bursting in gigabit ethernet in the MAC layer?

Avoids the overhead of CSMA/CD by sending multiple small frames back-to-back until it reaches a minimum transmission time

T/F: In traditional ethernet, CSMA/CD requires that a frame be long enough for collisions to be detected

True

What are jumbo frames in Gigabit Ethernet?

Ethernet frames larger than the 1518 byte limit, up to 8720 bytes. Used in LANs for efficiency, but not supported over the internet.

Why can’t jumbo frames be used on the internet?

Not all devices and networks between source and destination support them.