COMP3122 COMP3122 Network ManagementNetwork Management

Richard HensonRichard Henson

April 2011April 2011

Week 10 – Connectivity IssuesWeek 10 – Connectivity Issues

Learning Objectives:Learning Objectives:– Explain the meaning of “connectivity”Explain the meaning of “connectivity”– Explain the similarities and differences in Explain the similarities and differences in

practical implementations that deliver client-practical implementations that deliver client-server functionality to the desktopserver functionality to the desktop

– identify the software and hardware identify the software and hardware requirements for data one type of network to requirements for data one type of network to be forwarded onto anotherbe forwarded onto another

Evolution of “connectivity”Evolution of “connectivity”

““The sum total of how well hardware & The sum total of how well hardware & software integrate to provide smooth software integrate to provide smooth passage of data between programs on passage of data between programs on different machines”different machines”

Now taken for granted; not always the Now taken for granted; not always the casecase– HUGE thank you to OSI (open Systems HUGE thank you to OSI (open Systems

Interconnect)Interconnect)

ProprietaryProprietary Systems  Systems  & “lock in”& “lock in”

Poor connectivity was once the norm…Poor connectivity was once the norm…– In the mainframe days, not necessarily In the mainframe days, not necessarily considered to be a considered to be a

problem by companies such as IBM and ICLproblem by companies such as IBM and ICL– ““locked” customers into their productslocked” customers into their products

This approach… not popular with customersThis approach… not popular with customers– want(ed) to be able to buy freelywant(ed) to be able to buy freely

Also a barrier to communication…Also a barrier to communication…– between companiesbetween companies– sometimes between sometimes between different parts of the same companydifferent parts of the same company

» becausebecause they were using incompatible systems to please local they were using incompatible systems to please local governments, etc…!governments, etc…!

More about Open More about Open SystemsSystems

Back in mid-1970s ISO (International Standards Back in mid-1970s ISO (International Standards Organisation) aware thatOrganisation) aware that the basic infrastructure the basic infrastructure for global digital communicationsfor global digital communications was rapidly was rapidly emerging in the form of the Interneemerging in the form of the Internett– decided that thedecided that the then current proprietary isolationist then current proprietary isolationist

stance was stance was not condunot condussive to the growth of effective ive to the growth of effective digital data communications on a world-wide basisdigital data communications on a world-wide basis

– aagreed that what was needed was greed that what was needed was open systemsopen systems

Open SystemsOpen Systems

Definition: Definition: a computer system that is “open” for a computer system that is “open” for the purpose of information exchange the purpose of information exchange

Open systems are therefore not restrictOpen systems are therefore not restricted to one ed to one particular manufacturers own system of particular manufacturers own system of communicatingcommunicating

Open systems should provideOpen systems should provide t the ability tohe ability to::– interchange applications and datainterchange applications and data– between systems with different underlying hardware between systems with different underlying hardware

and softwareand software

Open Systems InterconnectOpen Systems Interconnect Historic OSI meeting in Geneva…Historic OSI meeting in Geneva…

– bold aims to produce a set of communication bold aims to produce a set of communication protocols that would allow any system to exchange protocols that would allow any system to exchange information with any other systeminformation with any other system

– model for connectivity already out there with open model for connectivity already out there with open source Internet protocols developed through RFCsource Internet protocols developed through RFC

BUT so many proprietary models to also be BUT so many proprietary models to also be represented…represented…– clearly had to be a compromiseclearly had to be a compromise– IBM were by far the biggest and most influentialIBM were by far the biggest and most influential

» also had a major say in what emerged…also had a major say in what emerged…

The OSI protocol stackThe OSI protocol stack

Physical Physical LayerLayer

Data link Data link LayerLayer

Network Network LayerLayer

Transport Transport LayerLayer

SessionSessionLayerLayer

Presentation Presentation LayerLayer

Application Application LayerLayer

Physical Physical LayerLayer

Data link Data link LayerLayer

Network Network LayerLayer

Transport Transport LayerLayer

SessionSessionLayerLayer

Presentation Presentation LayerLayer

Application Application LayerLayer

TransmitTransmitStationStation

ReceiveReceiveStationStation

AH DATA

PH AH DATA

SH PH AH DATA

TH SH PH AH DATA

NH TH SH PH AH DATA

LH NH TH SH PH AH DATA LT

DATA AH

DATA AH PH

DATA AH PH SH

DATA AH PH SH TH

DATA AH PH SH TH NH

LT DATA AH PH SH TH NH LH

LinkLink

Focus on Levels 3 & 4Focus on Levels 3 & 4

Network Network LayerLayer

Transport Transport LayerLayer

User SpecifiesUser SpecifiesServiceService

NetworkNetworkServiceService

Network providesNetwork providesServiceService

Network layer service definitions

Importance of levels 3 & 4Importance of levels 3 & 4 Need to be Need to be downwards compatibledownwards compatible with the with the

“hardware oriented” aspects of network “hardware oriented” aspects of network messagingmessaging– e.g. network card drivers (levels 1 & 2)e.g. network card drivers (levels 1 & 2)

Also Also upwardly compatibleupwardly compatible with “user with “user orientated” aspects (levels 6/7), through: orientated” aspects (levels 6/7), through: – ““Sockets” interfaceSockets” interface

» Originated with UnixOriginated with Unix» Adapted for NTAdapted for NT

– NETBIOS interfaceNETBIOS interface» Preferred option for Windows applicationsPreferred option for Windows applications

LAN Operating Systems LAN Operating Systems and OSI layersand OSI layers

Comparing levels 3,4 and 7…Comparing levels 3,4 and 7…– Novell NetwareNovell Netware

» network protocol: IPX/SPXnetwork protocol: IPX/SPX» resources located using: NDSresources located using: NDS

– Unix (in its many forms)Unix (in its many forms)» network protocol: TCP/IPnetwork protocol: TCP/IP» resources located using: NFSresources located using: NFS

– AppleApple» network protocol: TCP/IPnetwork protocol: TCP/IP» resources located with: Open Directoryresources located with: Open Directory

– Windows XP/2K3Windows XP/2K3» network protocol: TCP/IPnetwork protocol: TCP/IP» resources located using: Active Directoryresources located using: Active Directory

Windows Networks and UnixWindows Networks and Unix Unix has been around since the mid-1970sUnix has been around since the mid-1970s

– been running TCP/IP almost as longbeen running TCP/IP almost as long– very stable & securevery stable & secure

Windows NT started in 1993 (!)Windows NT started in 1993 (!)– Changed to use TCP/IP Changed to use TCP/IP

(original used a Microsoft protocol(original used a Microsoft protocol– pitched as a direct rival for Unix, then adopted & pitched as a direct rival for Unix, then adopted &

adapted TCP/IP making mixed environments adapted TCP/IP making mixed environments possiblepossible

NOW, two types peacefully co-existNOW, two types peacefully co-exist– something to do with the common protocol?something to do with the common protocol?

Principles of Connectivity - 1Principles of Connectivity - 1 For a client to connect to…For a client to connect to…

– another computer, the two devices need a common another computer, the two devices need a common protocol covering all 7 OSI layersprotocol covering all 7 OSI layers

– a network, it does need to be able to run the default a network, it does need to be able to run the default protocol for that networkprotocol for that network

Example:Example:– for a Windows Server machine to connect to for a Windows Server machine to connect to

a Netware server it needs to run IPX/SPXa Netware server it needs to run IPX/SPX» can easily be added to the client machine’s protocol can easily be added to the client machine’s protocol

stackstack» connection to Netware servers then possible via connection to Netware servers then possible via

hub/router and the Novell loginhub/router and the Novell login

Principles of Connectivity - 2Principles of Connectivity - 2 Client machines on one network should also Client machines on one network should also

be able to connect to resources on another be able to connect to resources on another network:network:– follow principle 1follow principle 1– install additional software on each client machine install additional software on each client machine

that will allow connection to resources using that will allow connection to resources using names from the other network’s resource names from the other network’s resource databasedatabase

Example: use a Netware printer from an XP Example: use a Netware printer from an XP clientclient– set up NWLinkset up NWLink– set up client service for Netware (CSNW)set up client service for Netware (CSNW)

Principles of Connectivity - 3Principles of Connectivity - 3

Client machines on one network should Client machines on one network should be able to connect to shared folders on be able to connect to shared folders on servers on another network:servers on another network:– follow principle 1follow principle 1– install software on the local server that will install software on the local server that will

connect to the relevant remote server(s)connect to the relevant remote server(s)– clients connect to the remote share via the clients connect to the remote share via the

local serverlocal server

Principles of Connectivity - 4Principles of Connectivity - 4 Example: use a Netware shared Example: use a Netware shared

directory from an XP clientdirectory from an XP client– install NWLink on Windows XP clients and serverinstall NWLink on Windows XP clients and server– install Gateway Services for Netware (GSNW) on install Gateway Services for Netware (GSNW) on

the relevant Windows 2003 Serverthe relevant Windows 2003 Server– the Netware share becomes available as a the Netware share becomes available as a

Windows 2003 Server shareWindows 2003 Server share– local clients can link to the share use the “map“ local clients can link to the share use the “map“

commandcommand

Using different level 3/4 Using different level 3/4 protocols in the same machineprotocols in the same machine For Netware…For Netware…

– a “mixed environment” will mean IPX/SPX and a “mixed environment” will mean IPX/SPX and TCP/IPTCP/IP

Both level 3/4 protocolsBoth level 3/4 protocols– can interface directly with the same level 1/2 can interface directly with the same level 1/2

protocolsprotocols– each has to be connected using its own bindingeach has to be connected using its own binding

Level 1/2 protocols provided by network card Level 1/2 protocols provided by network card softwaresoftware

Configuring Network Cards for Configuring Network Cards for Different Level 3/4 ProtocolsDifferent Level 3/4 Protocols TCP/IP just needs IP addressesTCP/IP just needs IP addresses

– client IP can be allocated by DHCP from a client IP can be allocated by DHCP from a serverserver

– default Internet Gateway & subnet mask should default Internet Gateway & subnet mask should be added manuallybe added manually

– Existing Internet Gateway IP address found Existing Internet Gateway IP address found using ipconfigusing ipconfig

– Link with any IP address can be checked using:Link with any IP address can be checked using:» ping <IP address>ping <IP address>

Configuring Network Cards for Configuring Network Cards for Different Level 3/4 ProtocolsDifferent Level 3/4 Protocols

Netware protocols getting scarcerNetware protocols getting scarcer– still found at UoW, at the moment…still found at UoW, at the moment…

Network cards on campus network still Network cards on campus network still configured according to “frame type” configured according to “frame type” (level 2)(level 2)

To interface with level 2 IPX/SPX needs:To interface with level 2 IPX/SPX needs:– frame type (relates to IEEE standard)frame type (relates to IEEE standard)– Netware Network Number (for routing)Netware Network Number (for routing)

Configuring Network Cards for Configuring Network Cards for Different Level 3/4 ProtocolsDifferent Level 3/4 Protocols

Using “NWLink”Using “NWLink”– Windows equivalent of IPX/SPXWindows equivalent of IPX/SPX– when installing, using when installing, using auto detection auto detection allows allows

the network card to provide the required the network card to provide the required information by itselfinformation by itself

» frame type on the server can be (default IEEE 802.2)frame type on the server can be (default IEEE 802.2)

» network numbernetwork number

Importance of Frame Type Importance of Frame Type for IPX protocolfor IPX protocol

Level 3 protocol interfaces with a network Level 3 protocol interfaces with a network card at each end of the communicationcard at each end of the communication– therefore essential that IPX frame type settings therefore essential that IPX frame type settings

are correctare correct Frame settings determined by the Netware Frame settings determined by the Netware

serverserver Can be displayed using:Can be displayed using:

– ipxroute configipxroute config NWLink should set frame type accordingly on NWLink should set frame type accordingly on

Windows XP machines wishing to be client to Windows XP machines wishing to be client to that Netware serverthat Netware server

Further (Deeper) aspects of Further (Deeper) aspects of IP addressingIP addressing

An IP address is made up of four fieldsAn IP address is made up of four fields Each field is represented by a single byteEach field is represented by a single byte Divided into two sections:Divided into two sections:

– host address (first field/s)host address (first field/s)– network address (remaining field/snetwork address (remaining field/s

Depending on the dividing position, Depending on the dividing position, categorised as different types (classes) of categorised as different types (classes) of addressaddress

IP Address ClassesIP Address Classes Several address classes:Several address classes:

– Class A (w then x.y.z)Class A (w then x.y.z)» For networks with many hostsFor networks with many hosts

» High order bit in first field set to 0High order bit in first field set to 0

– Class B (w.x then y.z)Class B (w.x then y.z)» For medium sized networksFor medium sized networks

» High order bits in fields 1 and 2 set to 1-0High order bits in fields 1 and 2 set to 1-0

– Class C (w.x.y then z)Class C (w.x.y then z)» For small LANsFor small LANs

» High order bits in fields 1,2,3,4 set to 1-1-0-1High order bits in fields 1,2,3,4 set to 1-1-0-1

Class A, B, C Addresses and first Class A, B, C Addresses and first IP fieldIP field

A: First bit of first field set to zero…A: First bit of first field set to zero…– IP decimal number always <128IP decimal number always <128

B: Fist bit set to 1, second to zero…B: Fist bit set to 1, second to zero…– IP decimal number always between 128 and 191IP decimal number always between 128 and 191

C: First and second bits set to 1, third to C: First and second bits set to 1, third to zero..zero..– IP decimal number always between 192 and 223IP decimal number always between 192 and 223

Class D and E IP AddressesClass D and E IP Addresses

Little used in practice…Little used in practice… D: First, second, third bits set to 1, D: First, second, third bits set to 1,

fourth to zerofourth to zero– IP decimal number always between 224 IP decimal number always between 224

and 239and 239 E: Fourth bit also set to one…E: Fourth bit also set to one…

– IP address always between 240 and 255IP address always between 240 and 255

Reserved IP addressesReserved IP addresses

127.0.0.1 to 127.255.255.255.255127.0.0.1 to 127.255.255.255.255– used for loopback testingused for loopback testing

Private addresses for Internal networks:Private addresses for Internal networks:– Class A 10.0.0.0 to 10.255.255.255Class A 10.0.0.0 to 10.255.255.255– Class B 172.16.0.0 to 172.31.255.255Class B 172.16.0.0 to 172.31.255.255– Class C 192.168.0.0 to 192.168.255.255Class C 192.168.0.0 to 192.168.255.255

Subnet MasksSubnet Masks Purpose is to inform the hosts which bits in Purpose is to inform the hosts which bits in

the full 32-bit IP address correspond to the the full 32-bit IP address correspond to the network address and which bits correspond to network address and which bits correspond to the host addressthe host address

Value depends on whether it is a class A, Value depends on whether it is a class A, class B, or class C network:class B, or class C network:– Class C: 255.255.255.0Class C: 255.255.255.0– Min for Class B: 255.255.0.0Min for Class B: 255.255.0.0– Min for Class A: 255.0.0.0Min for Class A: 255.0.0.0

Subnet Marks and Network SizeSubnet Marks and Network Size

1subnet = 255 computers!1subnet = 255 computers! 255.0.0.0 subnet mask255.0.0.0 subnet mask

– between 1 and 16 millionbetween 1 and 16 million 255.255.0.0 subnet mask255.255.0.0 subnet mask

– between 1 and 65535between 1 and 65535 255.255.255.0 subnet mask255.255.255.0 subnet mask

– between 1 and 255between 1 and 255

Subnet Masks and Network Subnet Masks and Network Packet OptimisationPacket Optimisation

Choice of an appropriate subnet mask Choice of an appropriate subnet mask relates directly to efficiency of relates directly to efficiency of management of network trafficmanagement of network traffic– determines packet header sizedetermines packet header size– should be a small as possibleshould be a small as possible

DHCP & Packet OptimisationDHCP & Packet Optimisation Range of IP addresses set using DHCP Range of IP addresses set using DHCP

known as a scopeknown as a scope– class C network… scope would be for a maximum class C network… scope would be for a maximum

of 254 addressesof 254 addresses

Once an IP address has been assigned to a Once an IP address has been assigned to a computer, it carries a leasecomputer, it carries a lease– Could be leased for the duration of the sessionCould be leased for the duration of the session

» e.g. ISP allocation to dial up clientse.g. ISP allocation to dial up clients

– Could be leased for several daysCould be leased for several days» e.g. allocation to clients on a LANe.g. allocation to clients on a LAN

Thanks for listeningThanks for listening