computer networks - introduction network management architectures

Computer Networks - Introduction Network Management Architectures &

Applications Network Management

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Week Topic

Week 1 Computer Networks - Network Management Architectures & Applications

Week 2 Network Management Standards Architectures & Applications

Week 3 Simple Network Management Protocol - SNMP v1, ASN, MIB, BER

Week 4 Network Management Functions - Fault

Week 5 Simple Network Management Protocol - SNMP v2 - Configuration

Week 6 Network Management Functions - Accounting

Week 7 Simple Network Management Protocol - SNMP v3 - Performance

Week 8 Network Management Functions - Security

Week 9 Midterm

Week 10 Remote Network Monitoring RMON 1, SLA

Week 11 Remote Network Monitoring RMON 2

Week 12 Management Tools, Systems and Applications

Week 13 NM Project Presentations



Lectures Schedule

Introduction

• The second industrial revolution radically changes the way we communicate virtually eliminating information lag.

• What problems does this create?

3

Recent Communications History

• 1834 Samuel Morse invents the telegraph

• 1876 Alexander Graham Bell makes the first long-distance phone call (10 miles)

• 1915 First transatlantic and transcontinental telephone service.

• 1948 Microwave links for telephone calls

• 1951 direct long distance dialing

4

Communications History Cont.

• 1962 Fax service is introduced

• 1965 widespread use of satellite long distance.

• 1968 Non Bell equipment allowed on phones system

• 1969 Picturephones

• 1969 DARPAnet

5


• 1970 Limited long-distance competition allowed

• 1984 AT&T is broken up creating a regulatory boundary between local phone service and long distance

• 1984 Cellular phone service starts

• 1990’s Cellular phone service explodes

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• 1996 Telecommunications Competition and Deregulation Act replaced all federal and state telecommunications law

• 1997 68 countries sign agreement to allow foreign telecommunications competition

7

Information Systems History

• 1950’s Batch processing and punch cards

• 1970’s Real-time transaction-oriented database-driven systems emerge

• 1990’s Macys is bankrupt in part due to their “old” 1970’s era IS infrastructure

• Read comparison between Macys and WalMart

8

Components of a Network

• Server – a device that stores data and often performs functions in addition to storage

• Client – A terminal or microcomputer from which a user or other application performs a work function

• Circuit – a wire, or set of wires and devices (modem, router, switch etc…) that carry information from the client to the server

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Types of Networks

• LAN – Local Area Network

• BN – Backbone Network

• MAN – Metropolitan Network

• WAN – Wide Area Network

• Intranet – A network used within an organization

• Extranet – Access for people from outside

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Network Models

• Used to break networks into component functions (layers) which then allows each layer to be addressed independently.

• The use of layers and different standards (and standards bodies) at these layers allows great flexibility in design, and competition between manufacturers.

11

OSI Model

• Produced in 1984

• Consists of seven layers

12

Internet Model

• Similar to the OSI model

• Compresses layers 5-7 into a single layer 5

• The textbook author claims the internet model has won the “war”. Is this true?

13

Functions at Layer 4 (TCP)

• Error detection/correction

• Linking higher layer software to the network layer

• Name resolution

• Breaking messages into pieces small enough to send over the network (MTU

14

Functions at Layer 3 (IP)

• Responsible for end-to-end routing of messages from sender to receiver

• Responsible for attaining the next address for messages as they hop from router to router across the internet

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Functions at Layer 2

• Responsible for moving messages from the sender to the receiver within a LAN.

• Controls the physical layer

• Formats the messages

• Provides error detection and correction

16

Functions at Layer 1

• Get the signal (electrical signal, light pulse, smoke signal) from one LAN device to the next.

• This layer includes hardware devices such as modems and hubs.

17

Two Types of Standards

• Formal

– Developed by an official industry or government agency

– These are often slow in developing and follow an already existing de facto standard

• De facto

– Emerge in the marketplace and are supported by multiple vendors but have to official standing

18

Standards Making Bodies

• IEEE

– The Institute of Electrical and Electronic Engineers

– Professional organization based in the United States

– Primarily responsible for existing LAN standards

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• ITU-T

– Responsible for creating technical standards for the united nations international telecommunications union (ITU)

– Open to public or private operators of communications networks from more then 200 countries

– Based in Geneva Switzerland

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• IETF

– Internet Engineering Task Force

– Open to everyone

– Manages consensus-building process through the use of RFC’s

– Oversees creation of Internet protocols and standards

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Future Trends

• Pervasive networking

• Integration of voice, video and data

• New information services

22

Application Architectures

• Host-Based Architectures

– Commonly a mainframe with terminals

• Client-Based Architectures

– Distribute PC based architecture with the computing power at the desktop

• Client-Server Architecture

– Applications software divided between desktop PC’s and central servers (fat vs. thin clients)

23

N-tier Architectures

• Two-tier – A client talks to a server (connecting to a web

server)

• Three-tier – A client talks to a web server which in turns

queries a database server to obtain the requested data

• N-tier – Same concept applied N times

24

Advantages of Client-Server

• Scalability

– N-tiered architecture gives a high degree of scalability

• Cost of infrastructure

– A set of smaller micro or mini computers and the associated software is often far less expensive then a mainframe approach

25

World Wide Web

• Create in 1989 at the CERN lab in Geneva Switzerland by Tim Berners-Lee

• A graphical interface was developed in 1993 by a team of students led by Marc Andreessen at the NCSA lab at the University of Illinois

• Adoption of the technology was immediate and rapid

26

Electronic Mail

• One of the earliest applications on the Internet (Early “killer” app)

• Cost and speed are among it’s strengths when compared with “snail mail”

• Important protocols and extensions to understand – SMTP (Simple Mail Transfer Protocol)

– IMAP (Internet Message Access Protocol)

– MIME (Multipurpose Internet Mail Extension)

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Other Important Applications

• FTP – File Transfer Protocol

– Provides the ability to transfer data to and from systems (primarily used in conjunction with UNIX servers)

• Telnet

– Provides the ability to login to a server from anywhere within a connected network

– The name is derived from making a TELephone connection via the NETwork.

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Components in Physical Layer

• Media

– Wires, fiber-optic strands

– Wireless

• Special-purpose devices

– Modems

– Repeaters/hubs

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Circuits

• Physical Circuit – Twisted pair cable, fiber, wireless link

– Exclusively committed to your data

• Logical Circuit – One of several, perhaps many circuits on a single

physical circuit

– Channel 12 on TV is a logical circuit, it rides on a coaxial cable or wireless (a physical circuit) along with many other logical circuits

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Types of Data

• Digital – Two possible values for any data bit (1 or 0)

– In a fiber circuit a light being on could represent a “1” while off represents a “0”

– In a copper circuit 5 volts could represent “1” while 0 volts represents “0”

• Analog – Signals are shaped like sound waves and are

constantly changing

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Modem/Codec

• MOdulate/DEModulate

– Translates digital data into a form that can be transmitted across an analog circuit such as a standard telephone line

• COder/DECoder

– Translates analog information into a form that can be transmitted across a digital circuit

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Circuit Configuration

• Point-to-Point

– A circuit with a device at each end

– Home modem

• Multipoint

– A single device at one end with many devices at the other end with either time-slicing or circuit switching

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Data Flow

• Simplex

– One way transmission (i.e. cable TV)

• Half-duplex

– Communication in both directions, only one way at a time (i.e. walkie-talkie)

• Full-duplex

– Communication in both ways, at the same time (i.e. telephone)

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Communication Media

• Guided media

– Twisted-pair, coaxial, fiber-optic

• Wireless media

– Radio, infrared, satellite

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Fiber Optic

• Multi mode

– Attenuation (weakening of the signal)

– Dispersion (spreading of the signal)

• Single mode

– Must use the precision of lasers as opposed to LED’s

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Coding

• Character

– A symbol with a constant understood meaning

• Byte

– A group of (typically) eight bits that is treated as a character

• ASCII (American Standard Code for Information Interchange)

– 7 or 8 bit code (typically 8)

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Transmission Modes

• Parallel

– All bits are sent simultaneously, in a 32-bit system then there must be paths to send all 32 bits at the same time

• Serial

– Each bit is sent one at a time,

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Digital Transmission

• Transmission of 1’s and 0’s

– With electricity this can be voltages with perhaps 0 volts representing a zero and 5 volts representing a 1 (unipolar)

– With light this can be using the state of the light with perhaps off representing a 0 and on representing a 1

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Manchester Encoding

• Used in Ethernet

• Unipolar coding scheme with a twist

– Voltage moving from a lower level to a higher level represents a “1”

– Voltage moving from high to low is a “0”

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Analog Transmission

• Telephone systems were originally designed to carry analog transmissions, electrical representations of the human voice

• Three key characteristics

– Amplitude

– Frequency

– Phase

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Modulation

• A carrier wave (ugly noise heard when modems are negotiating) is sent between modems, the shape of the wave is altered to represent 1’s and 0’s

• These “shape changes” are referred to as modulation

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Modulation Techniques

• Amplitude

– Modifying the height of the wave

• Frequency

– Modifying the frequency (the number of waves per second) of the wave

• Phase

– Modifying the point in phase at which the wave starts

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Amplitude Modulation

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Frequency Modulation

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Phase Modulation

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Two-bit Amplitude Modulation

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Modulation Techniques

• The various modulation techniques discussed can be combined as well

• QAM (Quadrature Amplitude Modulation)

– Combines eight phases (three bits) and two amplitudes (one bit) for a total of four bits

• TCM (Trellis Code Modulation)

– Similar to QAM but can transmit up to ten bits per symbol

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Bits Baud and Symbol

• Bits (specifically bits per second) are generally the important measurement in data communications as symbols are composed of bits

• There is a common misconception that these terms are interchangeable, baud refers to the number of symbols per second as opposed to the number of bits per second

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Voice Circuit Capacity

• Home analog phone lines have a bandwidth range from 0 to 4000 Hz

• The human ear can detect sounds up to ~14,000 Hz so very high pitch sounds can’t be transmitted over an analog phone line

• Digital circuits used to tie analog phone lines together have a bandwidth of 64,000 bits per second (bps)

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Modem Technologies

• V.34+

– Transmits up to 33,600 bps

• V.44 (Compression)

– Builds a dictionary of character combinations being sent over the circuit

– When a combination is repeated the dictionary reference is sent as opposed to the characters

– Average throughput is ~ 6:1

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Codec

• Converts Analog data into a digital form for transmission over a digital system and back

• The analog signal is translated into a binary number

• This digital signal is an approximation of the original with the quality depending on the resolution by either increasing the amplitude levels or increasing the sampling rate

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Telephone Transmission

• The “local loop” is the circuit from the phone company CO (the building between 3rd and 4th streets and Chestnut and Hazel streets) uses analog transmission

• Once the signal reaches the phone company office it is converted to digital form and is then sent to it’s destination CO

• Even local calls are converted to digital

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Pulse Code Modulation

• PCM is used in phone company CODEC’s in North America

• PCM samples the data 8,000 times (twice the highest frequency within the phone system

• Eight bits are generated for each sample, thus the phone system uses the 8 bits * 8,000 samples for a data rate of 64,000 bps

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ADPCM

• Adaptive Differential Pulse Code Modulation

• Similar to PCM except it only sends the difference between the former and the new signal

• Data rates as low as 8Kbps can be obtained, 32Kbps is the lowest providing sufficient quality so that the user doesn’t notice

• The use of ADPCM is the reason that some users can’t get a modem connection above 26,200 bps

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Analog/Digital Modems

• Uses PCM backward

• Sends 8,000 samples per second

• Uses 7 bits (one is lost for control purposes

• 7 bits * 8,000 samples = 56,000 bits

• V.92 modems do this in each direction and due to technical constraints are limited to ~52,000 bps downstream and ~42,000 bps upstream

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Multiplexing

• Using one high-speed circuit to carry the traffic of multiple lower-speed circuits

• FDM

• TDM

• WDM (form of FDM)

• DWM (combination of FDM and TDM)

– Has reached 1.25 terabits already and is expected to reach 1 petabit within a few years

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Frequency Division Multiplexing

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Time Division Multiplexing

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Inverse Multiplexing

• Using a series of lower-speed circuits to connect two high-speed circuits together

• Technology has been proprietary until just recently

• The BONDING (Bandwidth ON Demand Interoperability Networking Group) standard is allowing vendors to interoperate today but this is still in its infancy

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Inverse Multiplexing

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Digital Subscriber Line

• Much of the available bandwidth in the local loop has gone unused for many years

• DSL uses this bandwidth by applying FDM to create three circuits comprised of the original phone line, a upstream data circuit and a downstream data circuit

• TDM and PM are also used to obtain various data rates and features

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Media Access Control

• A mechanism used to control when computers transmit

• Important when using half-duplex circuits or multipoint configurations

• Two fundamental approaches

– Controlled Access

– Contention

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Controlled Access

• X-ON/X-OFF

• Polling

– Roll Call Polling: one device in the circuit is a “master” and checks with each other device on its wire to see if they have something to say

– Hub Polling (token passing): one computer starts the poll and passes it to the next, when a computer with something to say receives the “token” then it can send its data

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Contention

• The opposite of controlled access, each device listens to see if someone else is talking, if not then it sends carrier and starts to talk

• CSMA/CD (Carrier Sense Multiple Access with Collision Detection) is used in Ethernet networks

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Network Errors

• Two types of network errors

– Data loss

– Data corruption

• Three approaches to dealing with errors

– Prevention

– Detection

– Correction

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Sources of Errors

• Line noise, distortion

• Line outages

• Impulse noise

• Cross-talk

• Attenuation

• Intermodulation noise

• Jitter

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Error Prevention

• Shielded cabling

• Cable location

• Cable selection (fiber vs. twisted pair)

• Cable installation and maintenance

68

Error Detection

• Parity

• Longitudinal redundancy checking

• Polynomial checking

– Checksum

– Cyclic Redundancy Check

• 16-bit CRC used in TCP

• 32-bit CRC used in Ethernet

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Error Correction via Retrans.

• Stop-and-wait ARQ

• Continuous ARQ

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Forward Error Correction

• Sufficient redundant data is included within the transmission to correct errors without retransmission

• Used heavily in satellite transmission

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Ethernet Protocols

• Ethernet (IEEE 802.3)

– Byte-count protocol

– Destination, length, LLC, SNAP, CRC-32

• Point-to-Point Protocol (PPP)

– Address

– Protocol

– Message length = 1,500 bytes

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Bridging/Switching

• MAC-layer address table for each interface

• Addresses behind a port are stored in memory

• Ethernet frames are checked at each interface to determine if they should be forwarded

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Transmission Efficiency

• Transmission efficiency = total information bits/total bits

• Throughput = transmission efficiency adjusted for errors and retransmissions

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TCP/IP

• TCP

– Layer 4

– Provides error detection (CRC-16)

– Breaks data into appropriate size blocks (MTU)

• IP

– Provides routing and addressing

– IPv4 (32-bit address)

– IPv6 (128-bit address)

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TCP Ports

• A computer can have multiple applications running, i.e. a machine can be running both a web server and an email server

• Commonly used ports

– SMTP – port 25

– WWW – port 80

– FTP – port 21

– Telnet – port 23

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Encapsulation

Packetizing

• Taking an outgoing message with a length too great to fit within the data-link maximum frame length (MTU) and breaking the message into appropriate lengths

• Function is performed by the transport layer

• With IPv4 the packet size is set for the local LAN and is adjusted if the message is sent across a link that requires a smaller MTU

78

Connection-oriented Routing

• A specific route “virtual route” is determined when the session is created

• A SYN packet is sent to create the virtual circuit

• A FIN packet is sent to tear the circuit down

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Connectionless Routing

• Uses UDP instead of TCP

• Packets can travel different routes

• Commonly used with applications such as DNS and DHCP which are not likely to send a packet that will have to be broken into pieces

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Quality of Service

• A special type of connection-oriented routing

• Classes of service are established and each application is assigned one of the classes

• Applications such as VoIP and video-conferencing may be in a higher priority class then SMTP or WWW

81

Internet Addresses

• Assigned by ICANN (Internet Corporation for Assigned Numbers and Names)

• Blocks of network addresses are assigned to organizations

• Often a large block of addresses are assigned to an organization

• These large blocks of addresses are broken into smaller blocks referred to as “subnets”

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Subnets

• There are many possible combinations when dividing a network address block into subnets

• It is also possible to merge two adjacent networks together into a single “supernet”

• Whether dividing a network into subnets or combining two or more networks into a supernet the subnet mask is the key

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Subnet Mask

• A subnet mask is a string of 1’s and 0’s

• A subnet mask of 255.255.255.0 indicates the first three bytes of the IP address are part of the network

• Another way of looking at this subnet mask would be 11111111.11111111.11111111.00000000

• A 1 indicates the corresponding bit in the IP address is part of the network designation

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Dynamic Addressing

• DHCP (Dynamic Host Configuration Protocol)

• When the computer is started it sends a message requesting that a DHCP server provide an IP address and other configuration allowing the computer to communicate via IP

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Layer 2 Address Resolution

• ARP (Address Resolution Protocol)

• Broadcast Message (all 1’s)

• Whoever has IP address xxx.xxx.xxx.xxx send me your Ethernet address

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Domain Name Service

• An Internet phone book

• When typing in www.csuchico.edu DNS will translate this application-layer address to the network-layer address of 132.241.82.24

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http://www.csuchico.edu/

Routing

• Packets are routed between networks based on a set of routing tables

• The routing tables can be manually programmed (static routing) or created by a routing protocol (dynamic routing)

• Routing Protocols

– Distance Vector (RIP)

– Link State (OSPF)

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Routing Protocols

• Interior routing protocols

– RIP, OSPF, EIGRP

• Exterior routing protocols

– OSPF, BGP

• Autonomous System

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Multicasting

• Three types of messages

– Unicast

– Broadcast

– Multicast

• IGMP (Internet Group Management Protocol)

– Each participating computer uses a common data-link layer address

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TCP/IP Example

• Work through the entire TCP/IP example at the end of chapter 5

– Known addresses, same subnet

– Known addresses, different subnet

– Unknown addresses

– TCP connections

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Why Use a LAN?

• Information Sharing

– Email

– File access

– Video conferencing

• Resource Sharing

– Printers

– Applications servers

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Dedicated Server vs. Peer-to-Peer

• Dedicated Server

– One or more server computers permanently assigned to being a network server

• File servers

• Print servers

• Peer-to-Peer

– No dedicated server

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LAN Components

• NIC (Network Interface Card)

• Network cables

– Twisted pair

• UTP/STP

• See Category Ratings in Technology Focus

– Coaxial cables

• BALUNs

– Fiber-optic cables

• Single-mode vs. multi-mode

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LAN Components Cont.

• Network hubs

• Network bridges/switches

• Network routers

• Network Operating System – Server/client software

• Network profile

• Storage Area Networks (SAN)

• Network Attached Storage (NAS)

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Ethernet (IEEE 802.3)

• Topology

– Logical vs. physical

• The logical topology of a traditional Ethernet network is a bus

• The physical topology is often a star

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Media Access Control

• With a bus topology there must be a mechanism to either prevent, or detect and deal with, collisions on the media

• CSMA/CD

• Full-duplex Ethernet

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Types of Ethernet

• 10Base-5

• 10Base-2

• 10Base-T

• 100Base-T

• 10/100 Ethernet

• 1000Base-T

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Switched Ethernet

• The switch replaces the hub in the network

• The hub repeats every bit of data out every port

• The switch sends the data out the port which is connected to the message recipient

• The switch uses a forwarding table that contains the Ethernet addresses of the computers connected to each port

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Wireless Ethernet

• IEEE 802.11

• The WEP standard has been completely cracked

• Uses CSMA/CA for media control

• Subject to the “hidden node” problem

• Has VCSM (Virtual Carrier Sense Method) as an option to work around the hidden node problem

100

Types of Wireless Ethernet

• IEEE 802.11b – DSSS – Allows speeds from 1 – 11 Mbps

depending on distance and interference

– FHSS – Allows speeds from 1 – 2 Mbps

• IEEE 802.11a – The standard is still incomplete

– Data rate is likely to be 54 Mbps on first iteration

– Actual throughput will likely be ~20Mbps

101

Other Wireless Technologies

• Infrared wireless – Requires line of site or white ceilings and walls

with diffused infrared

• Bluetooth – Slated to become standardized as IEEE 803.15

– Short range networks referred to as piconets with no more then 8 devices

– Uses controlled access media access control

– Less then 1Mbps throughput

102

Reducing Network Demand

• Placing heavily-used applications or data modules on each client computer

• Network segmentation – note this is really increasing supply rather then reducing demand

103

Backbone Network Components

• Bridges

– Operating at the data-link layer (MAC address)

• Routers

– Operating at the network layer (IP address)

• Gateways

– Operating at the transport layer (note that this disagrees with the authors table 7-1)

104

Backbone Network Components

• Collapsed backbone

– Chassis-based

– Rack-based

• VLAN’s

– Port-based

– MAC-based

– IP-based

– Application-based

105

ATM

• Four key differences between Ethernet and ATM in the backbone

– 53-byte fixed-length cells

– No error correction

– Virtual Channel addressing as opposed to fixed addresses with the path and circuit numbers

– Built in Class-of-Service (CoS) and Quality-of-Service (QoS)

106

ATM

• Classes of Service

– CBR

– VBR-RT

– VBR-NRT

– ABR

– UBR

• LANE vs. MPOA

• SVC vs. PVC

107

MAN’s

• Generally constrained to a city or small region between 3 and 30 miles

• Generally deployed via either wireless technology or services leased from a carrier

• Moderate levels of regulation

108

WAN’s

• Connecting over potentially great distances

• Generally deployed via circuits leased from Common Carriers

• Very heavily regulated within North America and usually even worse oversees

109

Circuit Switched Networks

• Usually depicted by a cloud with your organizations data traveling with many others across the same physical circuits

• POTS

• ISDN

– BRI

– PRI

– Broadband

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Dedicated Circuit Networks

• Dedicated circuits or dedicated bandwidth within carrier circuits

• Ring Architecture

• Star Architecture

• Mesh Architecture

111

T Carrier Services

• Based on the 64Kbps channel required for a digitized voice connection

• T1 – 24 channels * 64Kbps = 1.536 Mbps – Control information is included bringing the total

circuit bandwidth for a stand-alone T1 to 1.544 Mbps

• T3 – 28 T1’s – 28 * 1.544Mbps = 43.008Mbps – With control information = 44,736Mbps

112

SONET

• SONET is a North American standard but the ITU recently adopted the SDH standard set which is nearly identical

• OC-1 = 51.84Mbps

• OC-3 = 3*OC-1 = 155.52 Mbps

• OC-12 = 12*OC-1 = 622.08 Mbps

113

Packet Switched Networks

• X.25 – older standard now seldom used in North America

• ATM

• Frame Relay

• Ethernet/IP Networks

114

Virtual Private Networks

• Intranet – Used to connect your organizations office via the

Internet

• Extranet – In addition to your organizations office you may

also include other organizations with which you do business

• Access – Remote access for employees

115

Internet Structure

• Internet architecture

• NAP’s, MAE’s, and ISP’s

– POP’s

• Peering

• Autonomous systems

116

Internet Access Technologies

• DSL

– Digital Subscriber Line

– Uses the local-loop

– A modem is placed in the home converting the data from the DSL format to Ethernet

• ADSL

– G.Lite

• VDSL

117

Internet Access Technologies

• Cable Modems

– DOCSIS

• Shared media means users compete with each other for bandwidth and unscrupulous neighbors could intercept your data

• Throughput suffers due to hardware compatibility issues that stem from cable TV infrastructure differences

118

Wireless

• Fixed wireless

– Wireless DSL

– Satellite

• Mobile Wireless

– WAP

– WAE

119

Internet Governance

• ISOC (Internet SOCiety)

– www.isoc.org

• IETF (Internet Engineering Task Force)

• IESG (Internet Engineering Steering Group)

– Each IETF working group is chaired by a member of the IESG

• IAB

• IRTF

120

Internet Domain Name Reg.

• Internet name and address registration was handled by John Postel until his death in 1998

• In 1998 ICANN (Internet Corporation for Assigned Names and Numbers) was formed

• In 1999 ICANN established the SRS and has now authorized more then 80 companies to issue Internet names and numbers

121

Internet 2

• Next Generation Internet

– vBNS

• Abilene

• CA*net 3

122

Why Networks Need Security

• The average cost to companies for a single security breach is slightly less then $1M

• This is a minor cost when compared to the loss of customer confidence

• The text indicates that 24 hours of downtime would cost Bank of America $50M

123

Types of Security Threats

• Disruptions

– Minor cable breaks to earthquakes

• Unauthorized Access

– More often the work of an employee then an outside hacker

124

Network Controls

• Controls are processes or steps to reduce or eliminate threats

• Three types of controls

– Controls that prevent threats

– Controls that detect threats

– Controls that correct threats

125

LAN Security

• Although sometimes overlooked a good first step is to ensure that the LAN hardware is physically secure

• Firewalls

– Packet-level

– Application-level

• NAT (Network Address Translation)

126

LAN Security

• Encryption

– Symmetric

• DES

• Triple DES

• AES

– Asymmetric (PKI)

• PGP (Pretty Good Privacy)

• SSL (Secure Sockets Layer)

• IPSec (IP Security)

127

Detecting Unauthorized Access

• IDS (Intrusion Detection Systems)

– Network-based

– Host-based

– Application-based

• Two IDS Techniques

– Misuse detection

– Anomaly detection

128

Network Design Process

• Traditional design process

• Building Block Design Process

– Needs analysis

– Technology design

– Cost assessment

• Why network projects fail

– Management focus 11-2

129

Request For Proposal

• Background information

• Network requirements

• Service requirements

• Bidding process

• Information required from vendor

130

Network Management

• Tasks performed by the network manager

• Five key management tasks

• Key network management skills

• Configuration management

131

H-132

Network Management

• Network management is the process of controlling a complex data network to maximize its efficiency and productivity

• The overall goal of network management is to help with the complexity of a data network and to ensure that data can go across it with maximum efficiency and transparency to the users

H-133

Network Management

• The International Organization for Standardization (ISO) Network Management Forum divided network management into five functional areas: – Fault Management

– Configuration Management

– Accounting Management

– Performance Management

– Security Management

H-134

Fault Management

• Is the process of locating problems, or faults, on the data network

• It involves the following steps:

– Discover the problem

– Isolate the problem

– Fix the problem (if possible)

H-135

Configuration Management

• The configuration of certain network devices controls the behavior of the data network

• Configuration management is the process of finding and setting up (configuring) these critical devices

H-136

Security Management

• Is the process of controlling access to information on the data network

• Provides a way to monitor access points and records information on a periodic basis

• Provides audit trails and sounds alarms for security breaches

H-137

Performance Management

• Involves measuring the performance of the network hardware, software, and media

• Examples of measured activities are:

– Overall throughput

– Percentage utilization

– Error rates

– Response time

H-138

Accounting Management

• Involves tracking individual’s utilization and grouping of network resources to ensure that users have sufficient resources

• Involves granting or removing permission for access to the network

H-139

Network Management Protocols

• A simple protocol defines common data formats and parameters and allows for easy retrieval of information

• A complex protocol adds some change capability and security

• An advanced protocol remotely executes network management tasks, is independent of the network protocol layer

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• So where is technology today?

– The most common protocols are:

• SNMP (Simple Network Management Protocol)

• SNMPv2 (SNMP version 2)

• CMIS/CMIP (Common Management Information Services/Common Management Information Protocol)

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• SNMP is beyond the simple protocol with adequate monitoring capabilities and some change capabilities

• SNMPv2 greatly enhances the SNMP feature set

• CMIS/CMIP approaches the advanced tool, but implementation issues have limited its use

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SNMP

• At the end of the 80’s, a solution was chosen called the Internet-standard Network Management Framework.

• This was a set of three documents defining: – A set of rules for describing management

information

– An initial set of managed objects

– A protocol used to exchange management information

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SNMP

• The SNMP protocol was a mere 36 pages within these documents

• The framework could be extended by defining new managed objects, but changes to the description rules or the protocol weren’t allowed.

• Today, there are literally hundreds of SNMP-capable products and thousands of managed object definitions.

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SNMP

• The work on SNMP security was completed in early 1992

• The security features introduced authentication, authorization, and privacy

• Unfortunately, this required a changed in the SNMP protocol which became SNMPv2

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SNMP

• A group was formed and their efforts were complete in early 1993

• There are 12 documents describing SNMPv2

• There are 3 basic commands that are used with SNMP:

– Get

– Set

– Get Next

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SNMP

• Authorization and authentication relies on a SNMP community string

• The community string(s) can be read-only or read-write

• The default community strings are:

– public (read-only)

– private (read-write)

• Community strings are case sensitive

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SNMP

• There are two approaches for the management system to obtain information from SNMP

– Traps

– Polling

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SNMP Traps

• When an event happens on a network device a trap is sent to the network management system

• A trap will contain:

– Network device name

– Time the event happened

– Type of event

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SNMP Traps

• Resources are required on the network device to generate a trap

• When a lot of events occur,the network bandwidth may be tied up with traps – Thresholds can be used to help

• Because the network device has a limited view, it is possible the management system has already received the information and the trap is redundant

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SNMP Polling

• The network management system periodically queries the network device for information

• The advantage is the network management system is in control and knows the “big picture”

• The disadvantage is the amount of delay from when an event occurs to when it’s noticed – Short interval, network bandwidth is wasted

– Long interval, response to events is too slow

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SNMP Traps/Polling

• When an event occurs, the network device generates a simple trap

• The management system then polls the network device to get the necessary information

• The management system also does low frequency polling as a backup to the trap

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SNMP MIBS

• Management Information Base (MIB) is a collection of related managed objects

• Used to define what information you can get back from the network device

• There are standard and enterprise specific MIBS

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SNMP MIBS

• Types of MIB Modules – Standard: These are the standard MIBS currently

designed to capture the core aspects of the particular technology

– Experimental: Temporary and if achieves standardization then it is placed in the standard module

– Enterprise-specific: Vendor specific MIBS that provide additional management capabilities for those features that require it

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SNMP MIB Tools

• A MIB compiler

• A MIB browser

• A MIB alias tool

• A MIB query tool

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CIMS/CIMP

• The OSI framework is an object-oriented paradigm

– Objects have attributes, generate events, and perform actions

– Objects are scoped by numerous hierarchies for the purpose of inheritance or containment

• Although the OSI model “sounds neat”, it is much more complicated and is not very common

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• These protocols do not state how to accomplish the goals of network management

• They give methods to monitor and configure network devices

• The challenge to analyze the information in an effective manner rests with software engineers who write network management applications

Conclusion

• Rich area of new buzz words

• Networking knowledge prerequisites

• Five areas of Network Management

• FCAPS

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