Chapter 4 653
18
Name four ATM layer service categories.
Constant Bit Rate (CBR).
Variable Bit Rate (VBR).
Unspecified Bit Rate (UBR).
Available Bit Rate (ABR).
19
Name four functions of the ATM physical layer.
Tracking of ATM cell boundaries.
Conversion of bits into cells.
Packaging of cells into frames.
Control of transmission and receipt of data.
20
Name two types of addresses used by ATM.
For private networks, ATM uses Network Service Access Point (NSAP) addresses and
E.164 addressing for public networks.
21
What is the function of the BUS?
The BUS is the Broadcast and Unknown Server. It is a multicast server that provides
information to the LES. If the LES does not know the location of a destination address,
the BUS discovers the address by broadcasting a request for information.
22
List three requirements of an efficient ATM address plan.
Address prefixes must be globally unique.
Addresses must be hierarchical and planned to match your network topology.
The address plan must allow for future network expansion.
23
True or false: A LAN Emulation Client can be an ATM end station or router, but a switch
or bridge cannot be configured as a LEC.
False. Catalyst 5000 can be configured as a LEC.
24
True or false: Congestion is caused by slow links. The problem can always be solved by
adding high-speed links.
False. An increase in link bandwidth can actually aggravate the congestion problem if the
higher-speed links make the network more unbalanced. Depending on the configuration,
higher-speed links can shift the bottleneck and make the congestion condition worse.
25
What is the function of the LAN Emulation Server?
The LES provides a registration facility for LECs to register unicast and multicast
addresses. The LES requests and maintains a list of LAN destination MAC addresses.
87200333.book Page 653 Wednesday, August 22, 2001 1:41 PM