Answers to the Chapter 3 Q&A Section 713
20
What portion of a MAC address encodes an identifier representing the manufacturer of the
card?
The first 3 bytes comprise the portion of a MAC address that encodes an identifier
representing the manufacturer of the card.
21
Are MAC addresses defined by a Layer 2 or Layer 3 protocol?
MAC addresses are defined by a Layer 2 protocol. Ethernet and Token Ring MAC
addresses are defined in the 802.3 and 802.5 specifications.
22
Are DLCI addresses defined by a Layer 2 or Layer 3 protocol?
DLCI addresses are defined by a Layer 2 protocol. Although they are not specifically
covered in this chapter, Frame Relay protocols do not define a logical addressing structure
that can usefully exist outside a Frame Relay network; by definition, the addresses would
be OSI Layer 2 equivalent.
23
Name two differences between Layer 3 addresses and Layer 2 addresses.
Layer 3 addresses can be used regardless of media type, whereas Layer 2 addresses are
useful only on a particular medium. Layer 3 addresses are designed with a minimum of
two parts, the first of which creates a grouping concept. Layer 2 addresses do not have a
grouping concept that allows the setup interfaces on the same medium to share the same
value in a portion of the data link address, which is how Layer 3 addresses are structured.
24
How many bits are present in an IP address?
IP addresses have 32 bits: a variable number in the network portion, and the rest of the 32
in the host portion. IP Version 6 uses a much larger address. Stay tuned!
25
How many bits are present in an IPX address?
IPX addresses have 80 bits: 32 bits in the network portion and 48 bits in the node portion.
26
How many bits are present in a MAC address?
MAC addresses have 48 bits. The first 24 bits for burned-in addresses represent a code that
identifies the manufacturer.
27
Name the two main parts of an IPX address. Which part identifies which "group" this
address is a member of?
Network number and node number are the two main parts of an IPX address. Addresses
with the same network number are in the same group. On LAN interfaces, the node
number is made to have the same value as the LAN MAC address.
apA.fm Page 713 Monday, March 20, 2000 5:24 PM