This document provides an overview of wide-area network (WAN) technologies and considerations for connecting local area networks (LANs). It discusses the building blocks of LAN/WAN networks such as hubs, bridges, switches, and routers. It then covers various telephone company WAN services like leased lines, switched 56, ISDN, frame relay, and ATM. The document outlines factors to consider like network design, protocols, and positioning technologies in the OSI model. It also compares different WAN technologies and provides guidance on choosing the right solution based on application needs.

1. T3: Wide-Area
LAN Interconnection
TUTORIAL

2.  Network design considerations
 Building blocks of a LAN/WAN network
 Intelligent hub
 Bridge
 LAN Switch
 Router
 Telephone Company Service Options
Leased Lines
Switched 56
ISDN
Frame Relay
ATM
Sequence

3. TCP/IP
SNA
IPX
DECnet
WAN
Novell LAN
Server
NETBIOS
IBM LAN
Server
IBM
Mainframe
UNIX
Workstation
Digital
Host
SNA IBM
Controller
AppleTalk
Apple
LAN
?
? ?
?
LAN/WAN Integration

4.  "Routable" vs. "Non-routable"
 TCP/IP
 IPX
 APPN
 Connectionless vs. connection-oriented transport
 TCP/IP
 IPX
 Broadcasts/route updates
 NetBIOS - Name Query
 TCP/IP - ARP, RIP, OSPF
 NetWare - Service Advertising Protocol (SAP), RIP
 Appletalk - Zone Information Protocol (ZIP) & AARP
 NetBIOS
 DECNET
 SNA
 SNA
 NetBIOS
Protocol Implications

5. Broadcast
Frame
Netware Get Nearest Server Query
Netware
Server
IPX
Broadcast Example

6.  Network design considerations
 Building blocks of a LAN/WAN network
 Intelligent hub
 Bridge
 LAN Switch
 Router
 Telco WAN Options
 Leased Lines
 Switched 56
 ISDN
 Frame Relay
 ATM
Agenda

7. application gateways
Presentation
Session
Transport
Network
Data
Link
Physical
Application
OSI
reference
model
hubs/multiplexors
bridges/switches
routers
tunneling/encapsulation
Positioning the Technologies

8. Source Routing Bridges
 At layer 1, isolates LAN segments to increase performance,
availability
 At layer 2, connects LANs into a single logical network
Functions independently of higher layer protocols
Operates as plug and play device
B
B
B
B
B
B
B
B
B
B
B
B
Transparent Bridges
Bridge

9. Bridge
Bridge
Bridge
Bridge
Bridge
Broadcast
Frame
Bridge
Bridge
Netware
Server
Netware Get Nearest Server Query
Broadcast Example

10. Token Ring
Bandwidth
0
1,000,000
2,000,000
3,000,000
4,000,000
4,000,000
1,544,000
528,000
256,000
128,000 64,000 19,200 9,600
T1 512K 256K 128K 64K 19.2K 9.6K
Relative Bandwidth of various media

11. Net A
Net C
Net D
Net E
Net 2
 Isolates logical subnetworks for more efficient network
utilization over WAN
 End station sends traffic to router; router forwards toward
ultimate destination
 Routing protocols allow router to understand network
topology
DSU/CSU
DSU/CSU
DSU/CSU Router
Router
Router
Net B
Net 3
Net 1
Router

12. Router
Router
Router
Router
Router
Broadcast
Frame
Bridge
Bridge
Netware
Server
Netware Get Nearest Server Query
Broadcast Example

13. Router WAN Considerations
 Port Density
 Port Cost
 Multiprotocol
 Primary Role
 Provide Managed Bandwidth for Slower WAN
Lines
Switch
Router
Router
WAN
9.6K
19.2K
64K
128K
512K
1.544 MB
LAN
4MB
10MB
16MB
100MB
155MB

14. WAN Challenge
 Enterprise spans multiple locations
 Requirement to share information or applications between
the locations
 Must balance performance against cost
Raleigh, NC
Richmond, VA

15. Components of a Wide-Area Network
Raleigh, NC
LEC
e.g. BellSouth
LEC
e.g. Bell Atlantic
IXC
e.g. AT&T, Sprint,
MCI,...
LEC = "Local Exchange Carrier"
IXC = "Inter-Exchange Carrier"
"Local Loop"
"Local Loop"
Richmond, VA

16. "Leased Line" Network
Raleigh, NC
LEC
LEC
IXC
LEC = "Local Exchange Carrier"
IXC = "Inter-Exchange Carrier"
= carrier multiplexing
Richmond, VA
 Carrier-provided facility
– "owned" bandwidth
– idle facility unused
 Low latency
– data simply relayed from one set of wires to
the next
 High cost
– especially for LAN applications

17. "Switched" Network Services
Raleigh, NC
LEC
LEC
IXC
 Analog dial
 Integrated Services Digital Network (ISDN)
Narrowband/Wideband/Broadband
 Switched 56
Richmond, VA
 Lowers Line Cost
 Charged for usage time
 Requires Call Setup & Call Take Down

18. WAN Technologies
Fast Packet
Switching
Frame Relay
Cell Relay
ATM
SMDS
– Efficient handling of variable-
sized frames
– data only (today)
– up to 1.5Mbps (today)
– Scalability (up to Gbps)
– QoS
– Voice/Vide
o/
Data/MM
 Cost-effective shared facilities
– with some built-in bandwidth management
 Low latency
– connection-oriented packet forwarding
– no hop-by-hop error checking
ATM: Asynchronous Transfer Mode
SMDS: Switched Multimegabit Data Services

19. Local Carrier Frame Relay Networking
Raleigh, NC
LEC
Frame Relay
Service
LEC = "Local Exchange Carrier"
= switch
Chapel Hill, NC

20. Inter-Exchange Frame Relay Networking
Raleigh, NC
LEC
LEC
Frame Relay
Network
LEC = "Local Exchange Carrier"
IXC = "Inter-Exchange Carrier"
= carrier multiplexing
= switch
Richmond, VA

21. Frame Relay Network
ROUTER
 Multiple virtual circuits over a Single Physical Link
 Pricing is usually lower and distance-insensitive
 however tariffs vary widely
 Can be a cost-effective alternative to private lines
 Bandwidth specified via Committed Information Rate & Burst Size
Router
Router
Router
Router

22. Cell Relay: Asynchronous Transfer Mode (ATM)
 Digital service starting at 45Mbps
 Fixed length "cells" of data
 Voice, video, data, multimedia
 Bandwidth Management
 ITU-T Q.2931
 Quality of Service

23. Quality of Service: A Key Concept...
– Quality of Service (QoS):
– A set of parameters that specify the required characteristics of a network path
– Include characteristics such as throughput, acceptable delay, tolerance for cell loss,...
– Specified in the ATM User to Network Interface (UNI) standards
 Gives users the ability to specify what is required
 Gives the "network" responsibility to:
– allocate and free the required network resources
– guarantee that committed network characteristics are met
"QoS"

24. Removing the WAN Bottleneck
Switch
Router
Router
LAN
4MB
10MB
16MB
100MB
155MB
WAN
9.6K
19.2K
64K
128K
512K
1.544 MB

25. ATM Extended Campus
Switch
 Extended LAN Environment
 Multiprotocol
 Campus Network "Business as Usual"
LAN
4MB
10MB
16MB
100MB
155MB
WAN
45MB
100MB
155MB
Switch

26. WAN Technologies
Fast Packet Switching
 Exploits new technologies to achieve
better performance characteristics
 Some built-in bandwidth management
Leased Lines
 Carrier-provided facility
– "owned" bandwidth
– idle facility unused
 Low latency
– data simply relayed from one set of wires
to the next
 High cost
– especially for LAN applications
Switched (Switched 56, ISDN)
 Lowers the cost of leased lines by
charging for usage time
 Requires effort to set up and tear
down call at appropriate times

27. Evolution: Initial Network
OKReset
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28. Saving Costs With Frame Relay
OKReset
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Frame Relay WAN

29. Evolution: Exploiting an ATM Backbone
OK
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Frame Relay
ATM Backbone
OK
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30. Evolution: Supporting Time-Sensitive Applications
OK
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OK
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Frame Relay
ATM Backbone
MM Server
MM Client
Multi-Service
Access Switch
Multi-Service
Access Switch
Video Conferencing
Video Conferencing
OK
Reset

31. How do you choose the right technology?
Data Center
Infrequent use
Frequent use
Dedicated Access
Switched Access
High Bandwidth

32. Choosing the Right Services
Switched Access - Occasional Use
Dedicated Access - Frequent Use
High-Bandwidth - Specialized Applications
Leased Line - low delay, simple, reliable
Frame Relay - potentially lower cost, cost effective support of
bursty traffic
Analog Dial - simple, low-bandwidth, inexpensive
Switched 56 - equipment inexpensive, future???
ISDN - expensive equipment (depending on features), service
pricing???
ATM - Voice, Video, Multimedia
SMDS - future???