Networking concepts

1. Token Ring
Ethernet
INTRODUCTION TO LOCAL AREA NETWORKS

2. SEQUENCE
LAN Basics
Network Operating System
Technology Choices
Ethernet and Fast Ethernet Basics
Implementation Scenarios
Token Ring Overview
Appendix Charts

3. Typical Client Environment
Deployment of Personal Computers
No standard applications
Peripherals supporting a single user
PBX ports supporting modems
June
Monthly
Report
Prodigy
MODEM
Word Perfect
MODEM
CompuServe
Microsoft Word
A/S400
Terminal
Dow Jones
MODEM
Ami Pro
5250
PC Support
No E-MAIL system
Mission Critiacl Applications not available to
all departments/users
No structured wiring system
Data sharing by way of diskette

4. Client Requirement
A/S400
Novell
Netware
INTERNET
Lotus
Notes
Printer Services
Provide users with access to corporate-wide applications and services

5. LANs provide the Physical Connection
A/S400
INTERNET
Ethernet Network
Router
Lotus
Notes
Novell
Netware
With a single network connection the user now has access to these resources

6. Network Operating System
The Network Operating System (NOS) allows for the sharing of resources, the operating system
resides on a server. Workstations that require shared resources are called requesters.
LAN Operating Systems
Novell Netware
IBM Eagle Servers
Banyan Vines
Windows NT
..
Types of Servers
Application
Communication
File
Print
Remote LAN
Access
LAN Operating Systems provide:
Security
– User-ID
– Password
– Access
Control
Resource Sharing
Types of Requesters
DOS
OS/2
Netware
...
..
NOS
Token Ring
Requester
NOS
Ethernet
Requester
Server

7. Technology Choices and Considerations
 Standards Information
– ISO
– IEEE
 Media
– The cable type
 Transmission technique
– The method used to carry electrical signals
 Topology
– The physical (or logical) layout
 Access control
– The rules for sharing

8. OSI Reference Model
OSI - Open Systems Interconnection - a seven layer reference model developed by the
International Organization for Standardization. The model provides a standard reference for
intercommunication between computer systems through a network using common protocols.
The application layer provides services to the actual applications to accomplish information transfer.
Applicatio
n
OSI
7
Presentation The presentation layer is concerned with the representation of user or system data.
6
Session The session layer provides mechanisms for organizing and structuring interaction between applications.
5
Transport
The transport layer provides transparent and reliable end to end data transfer, relying on lower layer functions for
handling peculiarities of the actual transfer medium.
4
Network The network layer provides the means to establish connections between networks. The standard also includes
procedures for the operational control of inter-network communications and for routing of information through multiple
networks.
3
Data Link
The data link layer provides the functions and protocols to transfer data between network devices and to detect
errors that may occur in the physical layer.
2
Physical The physical layer is responsible for physically transmitting the data over the communications link It provides the
mechanical, electrical, functional and procedural standards to access the physical medium.
1

9. IEEE 802 LAN Standards
IEEE 802 - Institute of Electrical and Electronics Engineers Project 802, a set of
standards for LAN architectures, giving vendors guidance for designing LAN products.
These standards align with the bottom two layers of the OSI Reference Model. The Data
Link layer has also been divided into two sublayers.
Data Link
Physical
2
1
OSI Layers IEEE 802 Layers
Logical Link Control IEEE 802.2
Media Access Control IEEE802.3 / 802.5
LLC - The logical link control sublayer is common to all MAC sublayers, in turn it also provides a consistent
view of the LAN to the upper layers regardless of the media and protocols being used.
MAC - The media access control sublayer describes the access method and contains the mechanisms to
control transmissions on the LAN so that two or more stations don't try to transmit data at the same time. The
physical connection specifications are also covered in the 802 standard.

10. IEEE 802 LAN Standards
IEEE 802.1 Higher Layer Interface Standard
IEEE 802.2 Logical Link Control Standard
Higher
Layers
Data
Link
Layer
Media
Access
Sub-Layer
Physical
Layer
CSMA/CD Token Bus Token-Ring Metro Area
Network
Wireless 100VG
Ethernet AnyLAN
802.3 802.4 802.5 802.6 802.11 802.12
LIAISON:
ANSI X3T9.5 FDDI
ATM ATM Forum
EIA-TIA 568 Building Wiring
ISO SC25-WG3 Cabling Standards
DQDB
ADVISORY COMMITTEES:
IEEE 802.3u Fast Ethernet
IEEE 802.7 Broad Band
IEEE 802.8 Fiber
IEEE 802.9 Voice/Data Integration
IEEE 802.10 LAN Security
IEEE 802.14 CATV Wide Area LAN

11. Network Communications Protocols
Application
Presentation
Session
Transport
Network
Data Link
Physical
OSI TCP/IP
Applications
NetWare
Applications Applications
APPN 3270
Applications
Logical Link Control
Media Access Control IEEE802.3 / 802.5
Cabling System
TCP
IP
NLM
SPX
IPX
NetBIOS
APPC
LU6.2
PU 2.1
Host
Terminal
Emulation
LAN Server
Applications

12. Media
Twisted Pair
Shielded Twisted Pair
Coaxial Cable
Twinaxial Cable
CATV Cable
Fiber Optics
Mixed Media

13. Transmission Technique
 Point-to-point
 Broadcast
 Baseband
 Broadband
C F
AB CF DG
B E G
D
A
C F
B E G
D
C
A
F
Baseband transmission - the entire bandwidth of a channel is devoted to one signal.
Bandwidth - the capacity of a communication channel, in digital channels, bandwidth is the rate at which data can be transmitted.
Broadband transmission - the bandwidth is shared among transmitting devices.

14. Common LAN Topologies
mesh
Ring
bus
star
tree
bus - workstations attached to transmission
medium, called a bus. Each frame is
broadcast to all stations attached.
mesh - every workstation connected to every
other workstation
ring - each station is connected to its adjacent
station by point to point links, thus
forming a ring
star - each station is connected to a central
controlling point, with a point to point
connection
tree - this topology is a variation of the bus

15. Wireless LAN
 600 - 800
feet
 195 - 250
meters
Number of Users
 Authorized:
Unlimited
 Logged-on: 50
max
Number of Cells
 Per Network:
60
 Overlapping:
20+
Open Space Range:
Performance
 Transmission Rate: 1
Mbps
 Average Real Data
Throughput
(with compression): .5 - 1.2 Mbps
Base Station
Remote Station
Remote
Station
Remote Station
In-building
range and coverage
dependent on
building construction
IBM Wireless LAN
Open-space
Range:
(radius) 800 feet
Open-space Coverage:
2.01 million sq ft
Base
Station
707 sq ft
30 feet
IBM Infrared Wireless LAN
Range (diameter):
Single-room
Coverage:
600 feet
IBM Wireless LAN Entry
Open-space
Range:
(radius)
Open-space Coverage:
1.13 million sq ft
Access
Point
Range & Coverage
Characteristics of Radio Frequency Cells

16. Physical Implementation of LAN Technologies
Today's LANs are designed using a star topology, Ethernet 10BaseT, Fast Ethernet, Token Ring, FDDI
and ATM all connect to a central concentrator device.
Wiring Closet
Concentrator's can be a hub, a switch or a combination of both. Connections to other closets or to a master concentrator
form the backbone. Wiring closets are also known as IDF's (intermediate distribution facility) and if used the master
concentrator is known as the MDF (main distribution facility)
to other wiring closets
Concentrator
to master concentrator

17. Ethernet - CSMA/CD
Understanding Carrier Sense Multiple Access with Collision Detection
Slot time - the length of time a transmitting station should monitor the bus before transmitting. It is the time during which a collision may occur and is the
maximum delay for a transmission to reach the far end of the network and for a collision to propagate back. Slot time is defined to be 51.2 microseconds
(512 bit times in a 10Mbps LAN). It also imposes a minimum 64 bytes on the size of the frames transmitted by each station.
bus
station A station B station C station D
 idle bus
 station A wants to transmit
 station A first listens to see if the bus is idle (slot time)
 station A determines the bus is idle and transmits data
 station B has data to transmit
 station B first listens to see if bus is idle
 station B determines bus is busy and waits until
– medium becomes idle and
– the inter packet gap (IPG) expires (9.6 us 10BaseT, .96 us
100BaseT)
 station A completes its transmission
 station A and B both want to transmit
 both station A and B listen
 station A and B begin to transmit
 a collision is detected and both stations begin to transmit a jamming signal to alert
active stations of the collision
 in response to this signal each station stops transmitting and uses a back off
algorithm to wait

18. Ethernet 10BASEn & 100BASEn Standards
xBASEn standards define the electrical and mechanical characteristics of the MAU and medium.
10BASEn is defined as:
10 = 10Mbps
Base = baseband transmission
n = indicates the cable segment length / type
Current Ethernet standards:
10BASE5
Thick coaxial cable
Commonly known as ThickNet
Maximum segment length = 500 meters
Maximum number of connections = 100
10BASE2
Thin coaxial cable
Commonly known as ThinNet
Maximum segment length = 185 meters
Maximum number of connections = 30
10BASET
Unshielded twisted pair
Common known as UTP
Maximum segment length = 100 meters
10BASEF
Multimode fiber cable
Maximum segment length = 2K
100BASEn is defined as:
100 = 100Mbps
Base = baseband transmission
n = indicates the cable segment length / type
Current Ethernet standards:
100BASET
Unshielded Twisted Pair (CAT-5)
Same characteristics as 10BASET
Maximum segment length = 100 meters
100BASET4
Unshielded twisted pair (CAT-3,4,5)
Different than 10BASET
Uses 3 pair to transmit data
Maximum segment length = 100 meters
100BASEF
Multimode fiber cable
Maximum segment length = 2K

19. 10Base5 Overview
Terminator
10Base5
MAU
AUI
Cable
500 meters
10BASE5
Thick coaxial cable
Commonly known as ThickNet
Maximum segment length = 500 meters
Maximum number of connections = 100
Cable type Ethernet 50 ohm PVC of Teflon FEP coaxial
Connectors N-Series
Termination Segment ends not attached to repeaters must be terminated with 50
ohm terminators
Transceiver cable Four stranded, twisted pair conductors with an overall shield and
insulating jacket
Data Rate 10 Megabits/sec
Max. Segment length 500 meters
Distances between transceivers 2.5 meter multiples
Max. number of transceivers 100 transceivers
Max. number of stations per network 1024 adapters
Max. transceiver cable length 50 meters
Impedance 50 ohms
Attenuation 8.5 dB for 500 meters at 10 MHz
Max. propagation delay/segment 2165 nanoseconds
DC resistance 5 ohms per segment

20. 10Base2 Overview
185 meters
BNC Connector
Terminator
10BASE2
10BASE2
Thin coaxial cable
Commonly known as ThinNet
Maximum segment length = 185 meter
Maximum number of connections = 30
Cable type RG-58A/U, 50 ohm coaxial
Connectors BNC type
Termination Segment ends not attached to repeaters must be terminated with 50
ohm terminators
Transceiver cable Four stranded, twisted pair conductors with an overall shield and
insulating jacket
Data Rate 10 Megabits/sec
Max. Segment length 185 meters
Min. distances between T-connectors 0.5 meter
Max. number of transceivers 30 transceivers
Max. number of stations per network 1024 adapters
Max. transceiver cable length 50 meters
Impedance 50 ohms
Attenuation 8.5 dB for 185 meters at 10 MHz
Max. propagation delay/segment 950 nanoseconds
DC resistance 10 ohms per segment

21. 10BaseT Brings Star Wiring to Ethernet
 Physical management simplified through star wiring
 Twisted-pair wiring used in place of coax
 Intelligent management capability can be added to hub
 Collision-based access protocol is unchanged
Server
Management capabilities include, error logging on a station by station basis, (crc checks, collisions)
Access control by MAC address, automatic bypass of failed lobes or nics.
HUB

22. 10BaseT Overview
RJ-45 connector both ends
HUB
10BASE -T
10BASE-T
Unshielded twisted pair
Commonly known as UTP
Maximum segment length = 100
meters
Full Duplex supported
Cable type 2 unshielded twisted pairs (UTP)
Connectors RJ-45
Termination No external terminators are required
Data rate 10 Megabits/sec
Single segment length 100 meters (point to point)
Max. number of repeaters / segment 2 multiport repeaters
Impedance 85-111 ohms
Attenuation 8.5 - 10 dB for 100m at 10 MHz
Max. propagation delay/segment 1000 nanoseconds

23. 100BaseT Overview
RJ-45 connector both ends
HUB
100BASE -T
100BASE-T
Unshielded twisted pair
Must use Category 5 UTP
Maximum segment length = 100
meters
Full Duplex supported
Cable type 2 unshielded twisted pairs (UTP)
Connectors RJ-45
Termination No external terminators are required
Data rate 100 Megabits/sec
Single segment length 100 meters (point to point)
Max. number of repeaters / segment 2 multiport repeaters
Impedance 85-111 ohms
Attenuation 8.5 - 10 dB for 100m at 10 MHz
Max. propagation delay/segment 1000 nanoseconds

24. 100BaseT4 Overview
RJ-45 connector both ends
HUB
100BASE -T4
100BASE-T4
Unshielded twisted pair
Support for Cat 3,4,5
Requires 4 Pair
*Uses 3 pair for transmitting data and 1 pair for
signaling
Maximum segment length = 100 meters
**Full Duplex not supported
Cable type 4 unshielded twisted pairs (UTP)
Connectors RJ-45
Termination No external terminators are required
Data rate 100 Megabits/sec
Single segment length 100 meters (point to point)
Max. number of repeaters / segment 2 multiport repeaters
Impedance 85-111 ohms
Attenuation 8.5 - 10 dB for 100m at 10 MHz
Max. propagation delay/segment 1000 nanoseconds

25. Repeater
OSI Reference Model
Application
Presentation
Session
Transport
Network
Data-Link
Physical Physical Physical
Application
Presentation
Session
Transport
Network
Data-Link
Physical
Repeater

26. Repeaters
MAU
AUI
Cable
Terminator
500 meters
MAU
AUI
Cable
Terminator
500 meters
REPEATER
Link Segment
Link Segment
Collision Domain Network
Use when:
The cable length exceeds recommended length
The number of attachments exceeds 100
Planning considerations:
Repeaters must be placed at the end of the link segment
Each repeater counts as an attachment
No more than 4 repeaters in a collision domain
No active duplicate paths between any two DTE's
Repeaters operate at the Physical Layer
Application
Presentation
Session
Transport
Network
Data-Link
Physical
OSI Reference Model

27. 10Mbps Ethernet Repeater Rule
REPEATER
REPEATER
REPEATER
REPEATER
5-4-3-2-1 4-3-2
5- no more than 5 segments
4- no more than 4 repeater hops
3- only 3 segments with nodes
2- inter-repeater links
1- makes 1 large collision domain
Collision Domain Network
10Base5 2500m

28. 100Mbps Ethernet Repeater Rule
For 100Mbps Ethernet the IEEE has designated two repeater classes. The class
designation coincides with the latency of the repeater. Total network segment length is
significantly reduced as compared to 10Mbps Ethernet.
Class 1
Counts as 1 Hop
100m 100m
Collision Domain Network
100BaseT 200m
Class 1 - only one repeater hop
Inter-repeater Link
5m max.
100m 100m
Collision Domain Network
100BaseT 205m
Counts as 2 Hops
Class 2 - up to two repeater hops
Class 2
Class 2

29. Coexistence of 10BaseT and 100BaseT
As a network managers migrate to higher speed technologies, the current install base needs to be
considered. The products available today help to protect that investment.
The AS/400 doesn't have available the 100Mbps card for Ethernet, the AS/400 can coexist in this environment. When
purchasing new PC's install 10/100 cards if the plan is to move to Fast Ethernet to the desktop.
Wiring Closet
100Mbps connection
10BaseT HUB
10BaseT connection
100BaseT HUB
100BaseT
10BaseT 10BaseT
100BaseT
Switched Uplink

30. 100Mbps Backbone Implementation
Ethernet Stackable Hub 100BaseT
Ethernet Switch 10BaseT
Ethernet Stackable Hub 10BaseT
Fiber Expansion Module (Switched)
100BaseT Universal Feature Card (UFC)
100BaseF Fiber Connection
100BaseT Copper Connection
10BaseT Copper Connection
Multimode Fiber
Building 1 Building 2
10BaseT
100BaseT
10BaseT

31. 100Mbps Backbone Implementation
Building 1 Building 2
Ethernet Collision Domain
Ethernet Switch 10BaseT or 100BaseT
100BaseF Ethernet
100BaseT Ethernet
10BaseT Ethernet
x
X
X
x
X
X
X Shared Ethernet Segment

32. Legacy Backbone Implementations
Networks were designed to segment users at the floor level and connect to either a distributed or
collapsed backbone. The collapsed backbone design made the management of the floor segment easier
since there was the presence of each segment in a central location.
Typically the backbone segment ran at the same speed as the floor segments, a second backbone using a alternate
path would be installed for redundancy
Fourth Floor
Third Floor
Second Floor
First Floor
Basement
Server
HUB
HUB
HUB
HUB
HUB
B
B
B
B
B
Fourth Floor
Third Floor
Second Floor
First Floor
Basement
Server
HUB
HUB
HUB
HUB
HUB
B B
B B
B

33. Switched Network Implementation
Fourth Floor
Third Floor
Second Floor
First Floor
Basement
Server
HUB
HUB
HUB
HUB
HUB
B B
B B
B
Legacy Network Example
Fourth Floor
Third Floor
Second Floor
First Floor
Basement
Server
HUB
HUB
HUB
HUB
HUB
EthernetSwitch
Switched Network Example
The bridges are replaced with a switch, collapse backbone design, the server is moved to a switch port

34. Star-Wired Token Ring
 Wiring concentrator converts physical star to logical ring
 Physical management is simplified by star wiring
 Intelligence in adapter, not concentrator

35. Token Ring Overview
Multi Station Access Unit
W1
W2 W3
W4
RI RO
W1 W2 W4
W3
Token Ring Networks
Use twisted pair media
UTP
STP
Operate at
4Mbps
16Mbps
Connect to wiring concentrators
Passive
Active
Implemented using a star topology
Frames are sent sequentially around the ring

36. Extending Token Ring Segments
Multi Station Access Units are connected
via the RI / RO ports using patch cables
RI RO
Multi Station Access Unit
RI RO
RI RO
RI RO
W1 W2 W4
W3 W9 W10 W12
W11
W20 W19 W17
W18
W28 W27 W25
W26
W1
W9
W17

37. Workstation Insertion onto Ring
W1
W2 W3
W4
Lobe Test
Cable wrap test to MSAU
If successful the MSAU relay is opened
The workstation is attached
Monitor Check
Waits for Active_Monitor_Present, Standby_ Monitor_Present, or Ring_Purge MAC frame
If seen the workstation will assume standby monitor
Duplicate Address Check
Sends a duplicate address test MAC frame, if duplicate address is found, the workstation will detach
Participation in Neighbor Notification
Learns its nearest active upstream neighbor (NAUN) and reports its own address to its active downstream neighbor
Request Initialization
A Request_Initialization MAC frame is sent to the ring parameter server, the ring parameter server responds with
an Initialize_Ring_Station MAC frame. Parameters which can be set are physical location, ring number and ring
authorization level.

38. Appendix Charts

39. Connecting Networks Using Bridges
Purpose:
connect two separate networks(i.e. collision domain networks)
can be local or remote
selectively forwards information between the networks
Use when network:
traffic needs to be segmented
protocols are different
are geographically dispersed
Types:
Transparent
Source Route
Source Route Transparent
Translational
Bridges operate at the Data-Link layer
Network A
Network B
Bridge
Physical
Address
001
Physical
Address
002
Physical
Address
101
Physical
Address
102
OSI Reference Model
Application
Presentation
Session
Transport
Network
Data-Link
Physical
Data-Link
Physical
Data-Link
Physical
Application
Presentation
Session
Transport
Network
Data-Link
Physical
Bridge
Appendix

40. Transparent Bridge
Transparent
– also called learning or spanning tree
– based on the principle that a sending device can
transmit a frame to a receiving device without
having any knowledge of that devices location
– frames are forwarded based on the MAC
sublayer destination address
– a filtering database is maintained in the bridge of
all known source address's
– each bridge counts as an attachment
– no active duplicate paths between any two
networks
Network A
Network B
Bridge
Physical
Address
001
Physical
Address
002
Physical
Address
101
Physical
Address
102
Transparent
Address Port
001 A
002 A
101 B
102 B
Filtering Database
B
A
Appendix

41. Source Route Bridge
Source Route
– requires sending device to specify the path the frame
should take to the receiving device
– the best path is determined by the discovery process
– the sending device sends a discovery frame to the
destination device
– the destination device responds with a discovery
response frame marked all routes broadcast
Physical
Address
001
Physical
Address
002
Ring 001
Ring 100
Physical
Address
101
Physical
Address
102
Bridge
Source Route
– as this frame passes through each bridge the bridge
number and the ring it is associated with is inserted in
the routing information field
– no more than 7 hops in a bridge network
– the sending device can receive more than one
response frame
– the sending device then picks the best route
Ring 010
Bridge
Source Route
Bridge
Source Route
A
B C
Appendix

42. Remote & Translational Bridges
Remote Bridges communicate via the wide area network
Network A
Bridge
Physical
Address
001
Physical
Address
002
Network B
Physical
Address
101
Physical
Address
102
Bridge
DSU
DSU
WAN
Network A
Bridge
Physical
Address
001
Physical
Address
002
Bridges can connect different media types
i.e.. Ethernet to Token Ring
Network B
Appendix

43. LAN Switching
Similar to a multiport transparent bridge
Forwards frames based on the destination MAC address
Able to forward frames at media speed (on the fly switching)
Collision domains stop at the switch port
Two types of LAN segments can be attached
Shared Media
Dedicated
Can be connected to a hub or repeater port
Can replace backbone network with switch
Increases backbone throughput by
Switch ports can be configured for full or half duplex
Switches can be cascaded to support additional segments
Uplinks available to connect to Higher Speed Networks
An AUI port is provided to connect to 10BASE2, 10BASE5, or Fiber
Ethernet Switching
Switches operate at the Data-Link layer
OSI Reference Model
Application
Presentation
Session
Transport
Network
Data-Link
Physical
Data-Link
Physical
Data-Link
Physical
Application
Presentation
Session
Transport
Network
Data-Link
Physical
Switch
10Mbps x # of ports
2
Appendix

44. Switch Implementation Example
HUB
HUB
HUB
HUB
Typical Ethernet Implementation
Switched Ethernet Implementation
FDX
Server
HUB HUB
Ethernet Switch
HUB
HUB
Appendix

45. Routers
Purpose:
Receive and transmit multiple protocols from one
LAN to another
Use when:
Network layer protocols require frames to be routed
Examples of routable protocols:
Internet Protocol - IP
Internet Packet Exchange - IPX
Internetwork Datagram Protocol - IDP
Routers operate at the Network layer
Router
Network Address 295.10
PNA
101
LNA
295.10.1
PNA
102
LNA
295.10.2
Network Network
OSI Reference Model
Application
Presentation
Session
Transport
Network
Data-Link
Physical
Data-Link
Physical
Data-Link
Physical
Application
Presentation
Session
Transport
Network
Data-Link
Physical
Route
r
Network Address 296.20
PNA
201
LNA
296.20.1
PNA
202
LNA
296.20.2
Router
Network Address 294.01
PNA
001
LNA
294.01.1
PNA
002
LNA
294.01.2
Router
WAN
Routers are configured with the network layer address of each of
its network connections
Routing tables are maintained about each router in the network
The configuration of the network can be static or dynamic
Appendix

46. Gateways
Network A
Physical
Address
001
Physical
Address
002
DSU
DSU
WAN
AS/400
Gateways operate at the Upper Layers of the OSI Model
Application
Presentation
Session
Transport
Network
Data-Link
Physical
OSI Reference Model
Application
Presentation
Session
Transport
Network
Data-Link
Physical
Application
Presentation
Session
Transport
Network
Data-Link
Physical
Application
Presentation
Session
Transport
Network
Data-Link
Physical
Gateway
PC Gateway
Forward packets of data between dissimilar networks
Operates at the transport layer and above
Gateway types:
PC
3270 Control Unit
FEP
Channel (Local)
Remote
Appendix