130 Chapter 4: ATM Solutions
Foundation Summary
This section contains tables that provide a convenient review of many key concepts in this
chapter. If you are already comfortable with the topics in this chapter, this summary could help
you recall a few details. If you have just read this chapter, this review should help solidify some
key facts. If you are doing your final preparation before the exam, Tables 4-2 through 4-4 are a
convenient way to review the day before the exam.
Table 4-2
Components of ATM LANE
Service
Function
Comments
LAN Emulation Client
(LEC)
An endpoint that forwards
data to the emulated ELAN
A single Cisco router or Catalyst switch can
be a LEC, LES, BUS, and LECS
simultaneously.
LAN Emulation Server
(LES)
Provides mapping between
ATM and LAN addresses
Broadcast and
Unknown Server (BUS)
Provides broadcasts for
packets that have an
unknown destination
LAN Emulation
Configuration Server
(LECS)
Welcomes new users to the
network
Table 4-3
Comparing ATM Addressing
Address
Length
Used for
PVC?
Used for
SVC?
Comments
NSAP
40 hex characters
No
Yes
Address must be globally
unique
VPI/VCI
2428 bits in
length
Yes
Yes
Address needs to be unique
to only the local link
Table 4-4
Comparing ATM Service Categories
Service Category
Loss?
Delay Variance?
Bandwidth?
Preferred Applications
CBR
Yes
Yes
Yes
Voice, constant bit rate video
ABR
Yes
No
Yes
Nonsensitive data
UBR
No
No
No
High-performance file transfers
87200333.book Page 130 Wednesday, August 22, 2001 2:18 PM