Chapter 7: Ethernet Switching
What is the special value assigned to the first 24 bits of a multicast MAC address transporting an IPv4 packet?
01-00-5E
What are the two sizes (minimum and expected maximum) of an Ethernet frame? (Choose two.)
64 bytes 1518 bytes
What is the minimum ethernet frame size?
64 bytes and maximum is 1518 bytes
What is an OUI (Organizationally Unique Identifier)
A unique 6 hexadecimal code obtained by the IEEE
What layer does ethernet operate in?
Data Link Layer Physical Layer
Shared Memory Buffering
Deposits all frames into a common memory buffer that all the ports on the switch share.
What does data encapsulation include?
Ethernet frame Ethernet Addressing Ethernet Error Detection
What happens when a NIC receives an Ethernet frame?
Examines the destinationMAC address matches it with the physical MAC address that is stored in RAM. If it matches, it passes the frame up the OSI layers, where de-encapsulation takes place (If there is no match, the device discards the fram)
What are the two variants of cut-through switching?
Fast-forward switching Fragment-free switching
cut-through switching
Forwards the frame before it is entirely received
Broadcast MAC Address
Frame is received and processed by every device on the Ethernet LAN A MAC address in which all bits are set to 1 (FF:FF:FF:FF:FF:FF). Flooded out of all Ethernet switch ports except the incoming port
What will a host on an Ethernet network do if it receives a frame with a unicast destination MAC address that does not match its own MAC address?
It will discard the frame
What does a switch use to make forwarding decisions?
Layer 2 Ethernet MAC addresses
Address Resolution Protocol (ARP)
Part of the TCP/IP protocol for determining the MAC address based on the IP address.
When a device is forwarding a message to an Ethernet network, what is included in the Ethernet header?
SourceMAC address and a DestinationMAC address
What are the frame forwarding methods?
Store-and-forward switching Cut-through switching
Which network device has the primary function to send data to a specific destination based on the information found in the MAC address table?
Switch
Which statement is true about MAC addresses?
The first three bytes are used by the vendor assigned OUI
What happens to runt frames received by a Cisco Ethernet switch?
The frame is dropped
What addressing information is recorded by a switch to build its MAC address table?
The source Layer 2 address of incoming frames
What will happen if the destination MAC is not in the table?
The switch will forward the frame out all ports except the incoming port
What statement describes a characteristic of MAC addresses?
They must be globally unique
What is auto-MDIX?
a feature that detects Ethernet cable type
store-and-forward switching
a switching method that receives the entire frame before forwarding and computes the CRC
What type of address is 01-00-5E-0A-00-02?
an address that reaches a specific group of hosts
What is the MAC sublayer responsible for?
data encapsulation; accessing the media
Port-based Memory Buffering
frames are stored in queues that are linked to specific incoming and outgoing ports
Ethernet multicast frame
received and processed by a group of devices that belong to the same multicast group Because multicast addresses represent a group of addresses (called host group). The source will always be unicast address
Which two functions or operations are performed by the MAC sublayer? (Choose two.)
It adds a header and trailer to form an OSI Layer 2 PDU It is responsible for Media Access Control
Which two characteristics describe Ethernet technology? (Choose two.)
It uses unique MAC addresses to ensure that data is sent to the appropriate destination It is supported by IEEE 802.3 standards
Which network device makes forwarding decisions based on the destination MAC address that is contained in the frame?
switch
unicast MAC address
the unique address used when a frame is sent from a single transmitting device to a single destination device.
