Practical Routers and Switches (Including TCP/IP and Ethernet) for Engineers and Technicians

Practical Routers & Switches
(Including TCP/IP and Ethernet) for Engineers & Technicians
Technology www.idc-online.com/slideshare Technology TTrraaiinniinngg tthhaatt Wwoorrkkss

Topics
• Overview
• Network Communication
• Types of Networks
• Open Systems
• Interoperability/Internetworking
• IEEE Standards
• Topologies
• Media Access Control

Network Connection Methodologies
Two basic methods of communication
for data exchange between computers
and peripherals:
• Circuit Switched
• Packet Switched

F u l l t i m e e x c l u s i v e c o n n e c t i o n e s t a b l i s h e d
a c r o s s n e t w o r k f o r d u r a t i o n o f e a c h c a l l .
A B
S w i t c h
1
T y p i c a l
D a t a F l o w s L o w u t i l i z a t i o n
S w i t c h
2
S w i t c h
n
C i r c u i t S w i t c h e d D a t a
o n e s h a r e d c i r c u i t
P a c k e t A s s e m b l e r
D i s a s s e m b l e r
P a c k e t S w i t c h e d N e t w o r k
0 0 1 0 0 1 1 1 0 0 1 0 1 1 0 1 1 0 1 0 1 1 0 1
e g . A d d r e s s
A t o E B t o D C t o F e t c
H i g h e r u t i l i z a t i o n
P a c k e t S w i t c h e d D a t a
A
B
C
T y p i c a l
D a t a F l o w s
D
E
F
D a t a

Circuit Switched
• Analogous to establishing a digital phone
connection.
• Once connection is established, communication
links is dedicated to user.
• No other communications/network activity affects
circuit capacity.

Packet Switching
• Used extensively in computer and related
systems.
• Data is divided into small units (“Packets”)
and multiplexed onto a common high speed
circuit.

Types of Networks

Local Area Networks
L A N ( 1 0 B a s e 5 ) e x a m p l e
5 0 0 m m a x

WAN Concept

Open Systems Interconnection
T h e O S I R e f e r e n c e M o d e l
A p p l i c a t i o n
P r e s e n t a t i o n
S e s s i o n
T r a n s p o r t
N e t w o r k
D a t a L i n k
P h y s i c a l

Open Systems Interconnection
P r o c e s s A P r o c e s s B
S e s s i o n
T r a n s p o r t
N e t w o r k
D a t a L i n k
P h y s i c a l
S e s s i o n
T r a n s p o r t
N e t w o r k
D a t a L i n k
P h y s i c a l
A p p l i c a t i o n P D U
P r e s e n t a t i o n P D U
S e s s i o n P D U
T r a n s p o r t P D U
P a c k e t s
F r a m e s
B i t s
C o m m u n i c a t i o n C h a n n e l
P h y s i c a l
D a t a

P H
P H
P H
M e s s a g e
M e s s a g e
M e s s a g e
M e s s a g e
M e s s a g e
M e s s a g e
M e s s a g e
M e s s a g e
A H
A H
A H
A H
A H
A H
S e s s i o n
T r a n s p o r t
N T
N T
P r o t o c o l C o n t r o l I n f o m a t i o n
( P C I ) o r H e a d e r
P r e D L H A H
N T
P H
P H
P H
S H
T H S H
S H
S H
S H
N H T H
T H
T H
D L H N H
N H
N e t w o r k
D L T
D L T
D a t a L i n k
P o s t
P y s i c a l

Descriptions of the Seven OSI Layers
• Application Layer (7)
• Presentation Layer (6)
• Session Layer (5)
• Transport Layer (4)
• Network Layer (3)
• Data Link Layer (2)
• Physical Layer (1)

Interoperability
• Defined as:
“the ability of two different networks to work
together”
– How networks can communicate and share data,
even though they may have different architectures.
– Also used to refer to the ability of different
software products to work together in the same
environment

Simplified OSI / RM
User
Application
Data Link
Physical
..........
Function blocks etc
"Layer 8"
Object oriented messages
broadcast, point-to-point
Fieldbus Layer Model
Token-pass, addressing,
error-checking
Twisted pair, fibre optic
bus, star

Physical Topologies
• Physically, there are three structures:
– Bus
– Star
– Ring
• Others ie hybrids are possible
• The logical topology may not reflect the
physical!

Bus Topology
Server

Bus Topology
• Advantages
– Uses relatively little cable compared to other
topologies
– Easy to add or remove nodes
– Simple & flexible architecture
– Broadcast messages are easy
– Failure of node does not affect network
– Inexpensive cable and connectors

Bus Topology
• Disadvantages
– Security problem - every node “hears” every message
– No automatic acknowledgment of messages
– Failure diagnosis can be difficult
– No automatic regeneration of signals

Star Topology
Node Node
Node
Hub
Node Node Node

Star Topology
• Advantages
– Troubleshooting & fault isolation are easy
– Easy to add / remove nodes & modify cable layout
– Failure of a node does not isolate any other
– Central hub allows monitoring for management
purposes
• Disadvantages
- Hub fails - network fails!
- Can require a lot of cabling

Ring Topology
Node
Node
Node
Node
Node
Node

Ring Topology
• Advantages
- Physical ring has minimal cable requirements
- No wiring centre needed
- Message can be automatically acknowledged
- Each node can regenerate the signal
• Disadvantages
- If a node fails, the ring fails
- Diagnosis & fault finding is difficult
- Adding /removing nodes disrupts network
- Limit on distance between nodes

Media Access
• Networks are for sharing!
• Each node will be connected to the shared
media via a Network Interface Card (also
called NI adapter)
• The card must be compatible with:
– Cable, or medium, type
– Computer bus
– Access method

LAN Access
• Only one node can transmit at a time
• Two main methods are in current use
– Contention
– Token Passing

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Practical Routers and Switches (Including TCP/IP and Ethernet) for Engineers and Technicians

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