Transcript OSI Reference Model - Long Island University

Network Elements and Services
CS 695 Network Management
Techniques
Prof. P. T. Chung
CS 695 Network Management Techniques
Outline
1. Networking - Concepts
2. Internet Communication Protocols
3. Network Elements
4. Network Management Related
Protocols
CS 695 Network Management Techniques
1. Networking - Concepts
Network Classifications
Network Technologies
Network Transmission Media
Network Elements
CS 695 Network Management Techniques
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)
CS 695 Network Management Techniques
Network Classifications (Conti)
Networks – Classified by Switching
Packet Switching
Circuit Switching
Networks – Classified by Transmission Media
Wired Network
Wireless Network
CS 695 Network Management Techniques
Bandwidth
Network Technologies
Gigabit
Ethernet
ATM
Fast
Ethernet
FDDI
MAN & SMDS
Ethernet
Token Ring
Frame Relay
ISDN (basic rate)
LAN
MAN
CS 695 Network Management Techniques
Distance
WAN
Transmission Media
Media
Wireline
Transmission
Electric
Conductors
Wireless
Transmission
Optical
Fiber
Radio
Twisted
Pair
Coaxial
Cable
Mono-mode
Infrared
Laser Links
Multi-mode
Microwave
CS 695 Network Management Techniques
Satellite
Transmission
Network Elements
LAN/Internet
Elements:
oRepeater
oHub
oBridge
oSwitch
oRouter
oGateway
WAN Elements:
o Modem
o Repeater
o ADM (Add-Drop Multiplexer)
o Cross-Connect
o Switch
o Multiplexer
o Concentrator
CS 695 Network Management Techniques
OSI Communication Architecture
Application
Application protocol
Application
Presentation
Presentation protocol
Presentation
Session
Session protocol
Session
Transport
Transport protocol
Transport
Network
Network
Network
Network
Data Link
Data Link
Data Link
Data Link
Physical
Physical
Physical
Physical
Host A
CS 695 Network Management Techniques
IMP
1
IMP 2
Host B
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
CS 695 Network Management Techniques
Internet Communication Protocol
Application
HTTP
SMTP
NNTP TELNET
SNMP
DNS
TCP
Transport
Internet
Network
Access
Data Link
FTP
ECHO
NTP
TIME
BOOTP DHCP
UDP
RIP
OSPF
BGP
ICMP
IGMP
IP
ARP
RARP
SLIP
PPP
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
CS 695 Network Management Techniques
IP Address
length：4 Bytes (32-Bit)
IP address:
Network Address
Subnet
Host Address)
Network
Subnet
Host
Host
CS 695 Network Management Techniques
IP Address Formats
CS 695 Network Management Techniques
CS 695 Network Management Techniques
CS 695 Network Management Techniques
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)
CS 695 Network Management Techniques
Routers and the IP Addressing Principle
• Routers have two or more addresses. One for
each interface.
CS 695 Network Management Techniques
Routing Table
IF ((Mask[i] & Destination Addr) = = Destination[i])
Forward to NextHop[i]
CS 695 Network Management Techniques
IP Forwarding Process
CS 695 Network Management Techniques
 IF ((Mask[i] & Destination Addr) = =
Destination[i])
Forward to NextHop[i]
CS 695 Network Management Techniques
Port
 Each host’s 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.
CS 695 Network Management Techniques
Common TCP/IP Application Services
and Port Numbers
TCP
21
23
25
53
79
80
110
119
123
FTP
Telnet
SMTP
DNS
Finger
HTTP
POP3
NNTP
NTP
UDP
53
67
69
161
162
DNS
BOOTP
TFTP
SNMP
SNMP-Trap
Port: 1~1024，for Internets
CS 695 Network Management Techniques
3. Network Elements
 Repeater
 Hub
 Bridge
 Switch
Router
Routing Switch
Gateway
CS 695 Network Management Techniques
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.
CS 695 Network Management Techniques
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.
CS 695 Network Management Techniques
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.
CS 695 Network Management Techniques
Bridge Example
Application
Application
Presentation
Presentation
Session
Session
Transport
Bridge
Network
Transport
Network
Data Link
Data Link
Data Link
Data Link
Physical
Physical
Physical
Physical
CS 695 Network Management Techniques
Switch
 Operates at Layer 2, the data link layer.
 Dispatches data to its destination, which it
determines from the packet’s lower-layer media
access control (MAC) address.
 Can limit traffic, and does not understand
network protocols.
CS 695 Network Management Techniques
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.
CS 695 Network Management Techniques
Router Example
Application
Application
Presentation
Presentation
Session
Session
Transport
Router
Transport
Network
Network
Network
Network
Data Link
Data Link
Data Link
Data Link
Physical
Physical
Physical
CS 695 Network Management Techniques
Physical
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.
CS 695 Network Management Techniques
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.
CS 695 Network Management Techniques
CS 695 Network Management Techniques
4. Network Management related
Protocols
SNMPv1
SNMPv2C
ICMP
ARP/RARP
DHCP
CS 695 Network Management Techniques
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.
CS 695 Network Management Techniques
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.
CS 695 Network Management Techniques
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.
CS 695 Network Management Techniques
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.
CS 695 Network Management Techniques
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.
CS 695 Network Management Techniques