Network Elements and Services

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Network Elements and Services

• CS 695 Network Management Techniques
• Prof. P. T. Chung

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Outline

• 1. Networking - Concepts
• 2. Internet Communication Protocols
• 3. Network Elements
• 4. Network Management Related Protocols

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1. Networking - Concepts

• Network Classifications
• Network Technologies
• Network Transmission Media
• Network Elements

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Network Classifications

• Networks Classified by Applications
• Data Communication Network
• Telecommunication Network
• Networks Classified by Distance
• LAN (Local Area Network)
• MAN (Metropolitan Area Network)
• WAN (Wide Area Network)

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Network Classifications (Conti)

• Networks Classified by Switching
• Packet Switching
• Circuit Switching
• Networks Classified by Transmission Media
• Wired Network
• Wireless Network

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Network Technologies
Gigabit Ethernet
ATM
Bandwidth
Fast Ethernet
FDDI
MAN SMDS
Frame Relay
Ethernet Token Ring
ISDN (basic rate)
Distance
LAN
MAN
WAN
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Transmission Media
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Network Elements

• LAN/Internet Elements
• Repeater
• Hub
• Bridge
• Switch
• Router
• Gateway

• WAN Elements
• Modem
• Repeater
• ADM (Add-Drop Multiplexer)
• Cross-Connect
• Switch
• Multiplexer
• Concentrator

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OSI Communication Architecture
Application protocol
Application
Application
Presentation protocol
Presentation
Presentation
Session protocol
Session
Session
Transport protocol
Transport
Transport
Network
Network
Network
Network
Data Link
Data Link
Data Link
Data Link
Physical
Physical
Physical
Physical
Host A
IMP 1
IMP 2
Host B
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2. Internet Communication Protocols

• The TCP/IP Protocol Architecture
• TCP/IP Layers ( or TCP/IP Suite )
• Application Layer
• Host-to-host, or transport layer
• Internet Layer
• Network Access Layer
• Physcical Layer

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Internet Communication Protocol
Application
Transport
Internet
Network Access
Data Link
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IP (Internet Protocol)

• Mainly provides multiple routes or Routing
  capabilities.
• Protocol Characteristics
• Connectionless, Unreliable
• IP Addressing
• Every host in TCP/IPnetwork has one 32-bit IP
  address.
• 140.131.76.1

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IP Address

• length4 Bytes (32-Bit)
• IP address
• Network Address
• Subnet
• Host Address)

Subnet
Host
Network
Host
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IP Address Formats
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Network Mask

• Set 1 for bits in Network Address and Subnet, and
  set 0 for other bits in IP address
• Class A ? 255.0.0.0
• Class B ? 255.255.0.0
• Class C ? 255.255.255.0
• IP address ? Logical AND (Network Mask, IP
  Address)

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Routers and the IP Addressing Principle

• Routers have two or more addresses. One for each
  interface.

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Routing Table
IF ((Maski Destination Addr)
Destinationi) Forward to NextHopi
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IP Forwarding Process
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• IF ((Maski Destination Addr)
  Destinationi)
• Forward to NextHopi

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Port

• Each hosts application layer (or processing
  layer) may have different application, service,
  or resource. Once a host received data from
  network, transport layer should have a mechanism
  to provide and distinquish network application
  service so that it could send data to correct
  processing program.
• Each upper-level communication application
  service or program maps to a unique TCP or UDP
  Port Number.

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Common TCP/IP Application Services and Port
Numbers
TCP
UDP
21 FTP 23 Telnet 25 SMTP 53 DNS 79 Finger 80 HTTP
110 POP3 119 NNTP 123 NTP
53 DNS 67 BOOTP 69 TFTP 161 SNMP 162 SNMP-Trap
Port 11024,for Internets
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3. Network Elements

• Repeater
• Hub
• Bridge
• Switch
• Router
• Routing Switch
• Gateway

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Repeater

• Operates at Layer 1, the physical layer.
• Connects two network segments into one large
  segment, or to expand an existing segment.
• Enhances data signals and thus can be used to
  extend maximum cabling distances.
• There is no network intelligence built into a
  simple repeater it is used strictly for signal
  propagation.

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Hub

• Operates at Layer 1, the physical layer.
• Simply a multiport repeater.
• Can be used to increase overall network size and
  number of nodes on a single segment.
• Can isolate faults within the subnet.
• Allows you to add stations to a segment without
  disrupting the entire network.

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Bridge

• Operates at Layer 2, the data link layer.
• Allows networks with different physical
  signaling, but with compatible data link
  addressing schemes, to communicate.
• Helps reduce traffic on a backbone LAN by
  filtering any information coming from one segment
  to another that does not need to be forwarded
  through the backbone.
• A common use for a bridge is to allow users on an
  Ethernet LAN and a Token Ring LAN to communicate
  with each other.

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Bridge Example
Application
Presentation
Session
Bridge
Transport
Data Link
Data Link
Physical
Physical
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Switch

• Operates at Layer 2, the data link layer.
• Dispatches data to its destination, which it
  determines from the packets lower-layer media
  access control (MAC) address.
• Can limit traffic, and does not understand
  network protocols.

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Router

• Operates at Layer 3, the network layer.
• Connects two networks with different
  technologies, and provides an intelligent means
  of transferring packets from one network to the
  other.
• Also forwards traffic among multiple hubs and
  bridges.

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Router Example
Application
Presentation
Session
Router
Transport
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Routing Switch

• Operates at Layer 3, the network layer.
• Combines the intelligence of a router with the
  efficiency of a switch,
• Routing data at higher speeds.

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Gateway

• Operates at Layer 7, the application layer.
• Can encompass all seven of the OSI model layers.
• A computing system that can be programmed to do
  any number of intricate protocol conversions and
  negotiations, such as between IP and IPX.

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4. Network Management related Protocols

• SNMPv1
• SNMPv2C
• ICMP
• ARP/RARP
• DHCP

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SNMPv1 (Simple Network Management Protocol
version 1)

• The most common management protocol in use in
  data networks.
• Provides a means of obtaining information from,
  and sending information to, network devices.
• Based on the manager-agent model.
• Uses Management Information Bases (MIBs) to
  exchange information between the manager and the
  agent.
• Using the SNMP protocol, a manager can query and
  modify the status and configuration information
  on each managed device by making requests to the
  agent running on the managed device.
• All commands use the UDP/IP protocol, which means
  that communication between the manager and the
  agent is connectionless.
• SNMP operates at Layer 7, the application layer.

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SNMPv2C (version 2)

• SNMPv2C includes the basic functions of SNMPv1.
• Adds
• new message types,
• standardized multi-protocol support,
• enhanced security,
• new MIB objects, and
• a way to co-exist with SNMPv1.
• SNMPv2C is useful for the retrieval of large
  amounts of management information using fewer
  network resources.

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ICMP (Internet Control Message Protocol)

• ICMP is the part of IP that handles error and
  control messages.
• ICMP operates at Layer 3, the network layer.
• ICMP supports an echo function, which sends a
  packet on a round-trip between two hosts.
• Ping, which sends a signal to see if an interface
  is up and running, is based on ICMP echo.
• ICMP can also send an address mask request that
  returns the address of the subnet mask on the
  remote system. This feature is important for
  non-SNMP devices.

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ARP/RARP (Address Resolution Protocol / Reverse
ARP)

• ARP/RARP are used at Layer 2, the link layer,
• ARP is used to map an IP address to a MAC (or
  link level, or hardware) address.
• RARP is used to map a MAC address to an IP
  address.

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DHCP(Dynamic Host Configuration Protocol)

• DHCP allows IP addresses to be allocated on a
  temporary basis (a lease).
• When the lease for an IP address expires, the
  address can be reused by a different node.
• This is useful in environments supporting mobile
  users who connect to the network with a laptop
  from many different places.
• This helps alleviate the problem of limited IP
  addresses and simplifies TCP/IP client
  configurations.