network fundamentals

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
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Frame Relay WAN

29. Evolution: Exploiting an ATM Backbone
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Frame Relay
ATM Backbone
OK
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30. Evolution: Supporting Time-Sensitive Applications
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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
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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???