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© 2007 Cisco Systems, Inc. All rights reserved.Valašské Meziříčí 18.04.2023 1
Connecting to the Network
Valašské Meziříčí 18.04.2023 2© 2007 Cisco Systems, Inc. All rights reserved.
Objectives
Concept of networking
Benefits of networks
Communication protocols
Local Ethernet network
Access layer devices
Distribution layer devices
Valašské Meziříčí 18.04.2023 3© 2007 Cisco Systems, Inc. All rights reserved.
Networking and Its Benefits
Types of networks
Valašské Meziříčí 18.04.2023 4© 2007 Cisco Systems, Inc. All rights reserved.
Networking and Its Benefits Examples of small, medium and large networks
Valašské Meziříčí 18.04.2023 5© 2007 Cisco Systems, Inc. All rights reserved.
Networking and Its Benefits
Components of an Information network
Valašské Meziříčí 18.04.2023 6© 2007 Cisco Systems, Inc. All rights reserved.
Networking and Its BenefitsRoles of computers on a network:
Clients and servers
Valašské Meziříčí 18.04.2023 7© 2007 Cisco Systems, Inc. All rights reserved.
Networking and Its Benefits Computer peer-to-peer network
Equal peer nodes function as both "clients" and "servers”.
Valašské Meziříčí 18.04.2023 8© 2007 Cisco Systems, Inc. All rights reserved.
Networking and Its Benefits Computer peer-to-peer network
Advantages
•Easy to set up•Simple•Low cost
Valašské Meziříčí 18.04.2023 9© 2007 Cisco Systems, Inc. All rights reserved.
Networking and Its Benefits Computer peer-to-peer network
Disadvantages
•Difficult to administer•Less secure•Not scalable•Slow: All devices both clients and servers
Valašské Meziříčí 18.04.2023 10© 2007 Cisco Systems, Inc. All rights reserved.
Network Topologies Logical and physical topologies Physical topology:
Where the devices are located.
computers
hubs
switches
routers
servers
Valašské Meziříčí 18.04.2023 11© 2007 Cisco Systems, Inc. All rights reserved.
Network Topologies Logical and physical topologies Logical
topology:
How devices communicate with one another.
Shows names, addresses, applications.
Valašské Meziříčí 18.04.2023 12© 2007 Cisco Systems, Inc. All rights reserved.
Communication Protocols
Communication: source, channel, destination
Valašské Meziříčí 18.04.2023 13© 2007 Cisco Systems, Inc. All rights reserved.
Communication Protocols Protocols = Set of Rules
When?
How long?
What box, paper?Sound, Light, Electricity?
Uni- , Multi-, Broad-cast?
What paragraphs?
Valašské Meziříčí 18.04.2023 14© 2007 Cisco Systems, Inc. All rights reserved.
Communication Protocols Encoding in human communication
What is she dreaming about?
What has he decoded?
Bad encoding - decoding...
Valašské Meziříčí 18.04.2023 15© 2007 Cisco Systems, Inc. All rights reserved.
Communication Protocols
Timing and access methods
Calling ... ... sleeping.
Bad timing ...
Valašské Meziříčí 18.04.2023 16© 2007 Cisco Systems, Inc. All rights reserved.
Communication Protocols
Message patterns
UnicastMulticast
Broadcast
Valašské Meziříčí 18.04.2023 17© 2007 Cisco Systems, Inc. All rights reserved.
Communication ProtocolsHuman communications: messages unit sizes timing encapsulation encoding message patterns
“Protocol”
Valašské Meziříčí 18.04.2023 18© 2007 Cisco Systems, Inc. All rights reserved.
Local Ethernet Network
Devices on a network must share common protocolsPeople must share
common languages
Valašské Meziříčí 18.04.2023 19© 2007 Cisco Systems, Inc. All rights reserved.
Local Ethernet Network
Standardization in computer communication protocols
Valašské Meziříčí 18.04.2023 20© 2007 Cisco Systems, Inc. All rights reserved.
Local Ethernet Network
Physical addressing: MAC addresses
Valašské Meziříčí 18.04.2023 21© 2007 Cisco Systems, Inc. All rights reserved.
Local Ethernet Network
Hierarchical design in an Ethernet Network
Valašské Meziříčí 18.04.2023 22© 2007 Cisco Systems, Inc. All rights reserved.
Local Ethernet Network
The logical network address: IP address
Network address
Host addresss
Which network?
Which host?
Valašské Meziříčí 18.04.2023 23© 2007 Cisco Systems, Inc. All rights reserved.
Access Layer Devices
The function of a Hub
... but all devices receive all messages.
1 source, ...
... 1 destination, ...
Only one communication at a time.
Valašské Meziříčí 18.04.2023 24© 2007 Cisco Systems, Inc. All rights reserved.
Access Layer Devices
The function of a Hub
2 sources sending at the same time ...
... collision !!!
Valašské Meziříčí 18.04.2023 25© 2007 Cisco Systems, Inc. All rights reserved.
Access Layer Devices
The function of switches
Switch learns MAC addresses and sends messages only to the right destination.
Many communications at a time.
Valašské Meziříčí 18.04.2023 26© 2007 Cisco Systems, Inc. All rights reserved.
Distribution Layer Devices
The function of routers
• Packets forwarding• Packets filtering• Logical grouping of devices• Joining – separating networks
Valašské Meziříčí 18.04.2023 27© 2007 Cisco Systems, Inc. All rights reserved.
Distribution Layer Devices
Default gateway
192.168.1.1
192.168.1.3aa.aa.aa.33.33.33
Inside a single network the computers know each other‘s addresses – no problem to communicate.
Valašské Meziříčí 18.04.2023 28© 2007 Cisco Systems, Inc. All rights reserved.
Distribution Layer Devices
Default gateway
192.168.1.1
192.168.1.3aa.aa.aa.33.33.33
But if they want to send a packet outside their own network, they need somebody, who knows the way.They need the Default gateway.
Valašské Meziříčí 18.04.2023 29© 2007 Cisco Systems, Inc. All rights reserved.
Summary
Networks carry data. Hosts can be clients, servers, or both. All communication needs a source, destination, and channel. Protocols are sets of rules. Protocols govern computer communications. Each network host needs
• physical MAC address • logical IP address.
