COMP3122 COMP3122 Network ManagementNetwork Management

Richard HensonRichard Henson

February 2011February 2011

Week 1: Technical Issues, Week 1: Technical Issues, People IssuesPeople Issues

Learning Objectives:Learning Objectives:– Explain the relative merits and problems Explain the relative merits and problems

involved in linking computers togetherinvolved in linking computers together– Analyse the knowledge and skills needed to Analyse the knowledge and skills needed to

manage the technology of a networkmanage the technology of a network– Analyse the range of protocols developed to Analyse the range of protocols developed to

manage users and resources so they can get manage users and resources so they can get what need from the networkwhat need from the network

This is NOT just another This is NOT just another technical networks module…technical networks module…

– Question for youQuestion for you– in groups of 3-4…in groups of 3-4…

What does it take to be a What does it take to be a goodgood network manager? network manager?

Some of the Qualities neededSome of the Qualities needed

knowledge of network technologiesknowledge of network technologies understanding of institutional ICT understanding of institutional ICT

strategy/policystrategy/policy patience and liking peoplepatience and liking people ability to explain consequences of ability to explain consequences of

actions (or inactions…) in non-actions (or inactions…) in non-technical terms to non-technical technical terms to non-technical people (like senior managers)people (like senior managers)

““Network Manager”Network Manager” is a fulfilling job is a fulfilling job

Easy to say…Easy to say… Whether this is true depends on many Whether this is true depends on many

things that are not necessarily to do with things that are not necessarily to do with technologytechnology

Factors? Over to you again…Factors? Over to you again…

Some Factors that affect the Some Factors that affect the demands on a Network Managerdemands on a Network Manager

the size of the organisationthe size of the organisation The number of sites within the The number of sites within the

organisationorganisation how much an organisation values its how much an organisation values its

datadata how much an organisations values its how much an organisations values its

employeesemployees The structure of the organisationThe structure of the organisation

How much do network managers How much do network managers get paid?get paid?

Estimates?Estimates?

““Network Manager” is often a Network Manager” is often a well-paid job…well-paid job…

Average salary (last 3 months):Average salary (last 3 months):– £47000 approx£47000 approx

High salary (large network)High salary (large network)– typically £65000typically £65000

Min salary (small network)Min salary (small network)– typically £20000typically £20000

Vacancies & salaries … currently increasingVacancies & salaries … currently increasing Ref:Ref:

– http://www.itjobswatch.co.uk/default.aspx?page=1&sortby=0http://www.itjobswatch.co.uk/default.aspx?page=1&sortby=0&orderby=0&q=network+manager&id=0&lid=2618&orderby=0&q=network+manager&id=0&lid=2618

More Questions, 1…More Questions, 1…

““Why link an organisation’s computers Why link an organisation’s computers or other digital devices together or other digital devices together anyway?anyway?

Question 2…Question 2…

““What are the challenges of linking What are the challenges of linking multiple devices together?multiple devices together?

Question 3…Question 3…

““What background knowledge and skills What background knowledge and skills does anyone even thinking about does anyone even thinking about administering, maintaining and administering, maintaining and provisioning a network need to have?”provisioning a network need to have?”

Technical aspects of Technical aspects of Network Management (1)Network Management (1)

Making sure computers can “talk” to one Making sure computers can “talk” to one another very, very quickly and another very, very quickly and accurately:accurately:– knowledge and configuration of knowledge and configuration of

communications protocolscommunications protocols– management of IP addressingmanagement of IP addressing– management of other naming systemsmanagement of other naming systems

Technical aspects of Technical aspects of Network Management (2)Network Management (2)

– management of hardware devices and management of hardware devices and media connecting them media connecting them

– management of network servicesmanagement of network services– management of login/transfer of management of login/transfer of

data/access to services as appropriate data/access to services as appropriate across different networksacross different networks

– anticipating/troubleshooting network anticipating/troubleshooting network problems including backup/recoveryproblems including backup/recovery

Communications ProtocolsCommunications Protocols A Protocol is a set of rules/proceduresA Protocol is a set of rules/procedures Computer protocol:Computer protocol:

– rules programmed into software, carried out by a rules programmed into software, carried out by a CPUCPU

Communications protocolCommunications protocol– therefore software that allows “intelligent” hardware therefore software that allows “intelligent” hardware

devices to use digital data to communicate rapidly devices to use digital data to communicate rapidly & accurately& accurately

Intelligent? The device must have…Intelligent? The device must have…– CPUCPU– storage capabilitystorage capability

Types of Types of Communications ProtocolCommunications Protocol

Many, many protocols have been Many, many protocols have been developed!developed!– rules/procedures depend on the rules/procedures depend on the

network…network…» number of devicesnumber of devices» issues involved in controlling the issues involved in controlling the

devices and datadevices and data» degree of control requireddegree of control required» speed of response requiredspeed of response required» many other factors…many other factors…

Specification of a ProtocolSpecification of a Protocol

Written as “psuedo code”Written as “psuedo code” Can then be translated into an Can then be translated into an

implementation in a variety of implementation in a variety of languageslanguages

Most network protocols written in “C” Most network protocols written in “C” then compiledthen compiled– code executes very fast…code executes very fast…

Familiarity with LAN hardware Familiarity with LAN hardware is ESSENTIAL…is ESSENTIAL… RepeatersRepeaters

– control up to OSI level 1 control up to OSI level 1 (i.e. no software))(i.e. no software))

BridgesBridges– control up to OSI level 2control up to OSI level 2

Routers & SwitchesRouters & Switches– control up to level 3control up to level 3

GatewaysGateways– control at least up to level 4control at least up to level 4– could be right up to level 7could be right up to level 7

Hubs and ControlHubs and Control A variety of hubs available. All need a power A variety of hubs available. All need a power

supply:supply:– simplest (unmanaged or passive) just cleans up simplest (unmanaged or passive) just cleans up

and splits the signaland splits the signal– managed hub or “switch” can either read:managed hub or “switch” can either read:

» frames & MAC addresses (level 2) - bridgingframes & MAC addresses (level 2) - bridging» packets and IP addresses (level 3) - routingpackets and IP addresses (level 3) - routing» either can manage traffic to optimise use of network mediaeither can manage traffic to optimise use of network media

– some switches can read even higher up the some switches can read even higher up the protocol stackprotocol stack

» e.g. transport layer ports (level 4)e.g. transport layer ports (level 4)» loading based on TCP dataloading based on TCP data

Software Development for Software Development for Network ProtocolsNetwork Protocols

Must include:Must include:– a naming/addressing system including all a naming/addressing system including all

network devicesnetwork devices– communication of addresses of sending and communication of addresses of sending and

receiving computersreceiving computers– a method of error checking and confirming a method of error checking and confirming

complete deliverycomplete delivery– resolution of other network-related issues…resolution of other network-related issues…

Examples of protocol stacks (OSI):Examples of protocol stacks (OSI):– TCP/IP (LAN or WAN)TCP/IP (LAN or WAN)– IPX/SPX (LAN only)IPX/SPX (LAN only)

IETFIETF The International organisation responsible for The International organisation responsible for

assessing and agreeing network management assessing and agreeing network management protocolsprotocols– established in 1984established in 1984– after OSI model became an International Standardafter OSI model became an International Standard

IETF and system of “peer review” of new protocols IETF and system of “peer review” of new protocols evolved from the small group of computer scientists evolved from the small group of computer scientists that developed the Internet (1969)that developed the Internet (1969)– draft protocol circulateddraft protocol circulated– if assessment panel of peer agrees, the draft becomes an if assessment panel of peer agrees, the draft becomes an

RFCRFC– 5759 RFCs have been issued to date…5759 RFCs have been issued to date…

Example of an early Example of an early Communications ProtocolCommunications Protocol

FTP: Original Spec offered by FTP: Original Spec offered by (Bhushan, 1971)(Bhushan, 1971)– documented in RFC 114documented in RFC 114

» http://community.roxen.com/developers/idocs/rfc/rfhttp://community.roxen.com/developers/idocs/rfc/rfc114.htmlc114.html

– comments on spec in RFC 141comments on spec in RFC 141– became part of the Internet infrastructure became part of the Internet infrastructure

via RFC 238via RFC 238– final improved version RFC 959 (in 1985)final improved version RFC 959 (in 1985)

The OSI seven layer The OSI seven layer software modelsoftware model

Agreed in the late 1970sAgreed in the late 1970s– based loosely on TCP/IP & IBM protocol modelsbased loosely on TCP/IP & IBM protocol models

Took until the late 1990s for most network Took until the late 1990s for most network software developers accepted it as a standardsoftware developers accepted it as a standard

Layers together make up a protocol stackLayers together make up a protocol stack– below layer 1, communications sent/received as below layer 1, communications sent/received as

digital signalsdigital signals– above level 7, visual communications reach the above level 7, visual communications reach the

human eyehuman eye

The OSI LayersThe OSI Layers

Physical LayerPhysical Layer

Data link LayerData link Layer

Network LayerNetwork Layer

Transport LayerTransport Layer

Session layerSession layer

Presentation LayerPresentation Layer

Application LayerApplication Layer

Networkmedium

Screendisplay

e.g. TCP

e.g. IP

Practical ExercisePractical Exercise Use the IETF website to locate RFCs Use the IETF website to locate RFCs

covering the following level 7 communication covering the following level 7 communication protocols. Make a note of the level 4 TCP or protocols. Make a note of the level 4 TCP or UDP port in each case:UDP port in each case:– SMTP (Simple Message Transfer Protocol)SMTP (Simple Message Transfer Protocol)– DNS (Domain Name System protocol)DNS (Domain Name System protocol)– HTTP (hypertext transfer protocol)HTTP (hypertext transfer protocol)– HTTP-s (secure http)HTTP-s (secure http)– POP3 (multiple message download to client)POP3 (multiple message download to client)

IETF Network Management IETF Network Management software modelsoftware model

Based on IETF Network Management Based on IETF Network Management Components, defined as:Components, defined as:– Network elementsNetwork elements– AgentsAgents– Managed object Management Information Base (MIB) Managed object Management Information Base (MIB) – Syntax notation Syntax notation – Structure of Management Information (SMI)Structure of Management Information (SMI)– Network management stations (NMSs)Network management stations (NMSs)– Management protocolManagement protocol– ““Parties”Parties”

Network ElementsNetwork Elements

Hardware devices such as computers, Hardware devices such as computers, routers, and terminal servers that are routers, and terminal servers that are connected to networks connected to networks

Sometimes called “managed devices”Sometimes called “managed devices”

AgentsAgents

Software modulesSoftware modules– reside in network elementsreside in network elements– Collect and store management information Collect and store management information

e.g.e.g.» number of error packets received by a network number of error packets received by a network

elementelement

Managed ObjectsManaged Objects Anything that can be managed…Anything that can be managed…

– e.g.:e.g.:» list of currently active TCP circuits in a particular host computerlist of currently active TCP circuits in a particular host computer

– differ from variables (particular object instances)differ from variables (particular object instances)» e.g. a single active TCP circuit in a particular host computere.g. a single active TCP circuit in a particular host computer

Can be scalarCan be scalar– defining a single object instancedefining a single object instance

or tabularor tabular– defining multiple, related instancesdefining multiple, related instances

Management information Management information Base (MIB) moduleBase (MIB) module

A Collection of related managed objects A Collection of related managed objects residing in a virtual information storeresiding in a virtual information store

Syntax notation Syntax notation (MIB managed objects)(MIB managed objects)

Language used to describe these objects in a Language used to describe these objects in a machine-independent formatmachine-independent format

Allows different types of computers to share Allows different types of computers to share informationinformation

Internet management systems use ASN.1 Internet management systems use ASN.1 – a subset of the International Organization for a subset of the International Organization for

Standardization's (ISO's) Open System Standardization's (ISO's) Open System Interconnection (OSI) Abstract Syntax Notation Interconnection (OSI) Abstract Syntax Notation

– to define to define » packets exchanged by the management protocolpackets exchanged by the management protocol» objects that are to be managedobjects that are to be managed

SMI (Structured Management SMI (Structured Management Information)Information)

Defines the rules for describing Defines the rules for describing management informationmanagement information

SMI itself defined using ASN.1SMI itself defined using ASN.1

Network management Network management stations (NMSs)stations (NMSs)

Physically, NMSs are usually engineering Physically, NMSs are usually engineering workstation-calibre computersworkstation-calibre computers– fast CPUsfast CPUs– mega pixel colour displaysmega pixel colour displays– substantial memorysubstantial memory– abundant disk spaceabundant disk space

Also called consoles…Also called consoles… Execute management applications that monitor and Execute management applications that monitor and

control network elementscontrol network elements At least one NMS must be present in each managed At least one NMS must be present in each managed

environmentenvironment

Management ProtocolManagement Protocol SNMP - the Internet community's de facto SNMP - the Internet community's de facto

standard management protocol standard management protocol – Used to convey management information between Used to convey management information between

agents and NMSsagents and NMSs Originally developed as a series of RFCsOriginally developed as a series of RFCs

– architectural Model for SNMParchitectural Model for SNMP» RFC 1065: Rose & McCloghrie, 1988 RFC 1065: Rose & McCloghrie, 1988

– MIB for SNMPMIB for SNMP» RFC 1066: Rose & McCloghrie, 1988 RFC 1066: Rose & McCloghrie, 1988

– The SNMP protocolThe SNMP protocol» RFC 1067: Case et al, 1988RFC 1067: Case et al, 1988

Rationalised in RFC 1157, agreed 1990Rationalised in RFC 1157, agreed 1990

Further Development of SNMPFurther Development of SNMP Evolved into SNMP v2 (RFC 1901, Evolved into SNMP v2 (RFC 1901,

agreed 1996) agreed 1996) – two new operationstwo new operations

» GetBulk - used to efficiently retrieve large blocks of GetBulk - used to efficiently retrieve large blocks of datadata

» Inform - allows one NMS to send trap information Inform - allows one NMS to send trap information to another NMS and to then receive a response to another NMS and to then receive a response

Later, SNMP v3 (RFC 2570, agreed Later, SNMP v3 (RFC 2570, agreed 1999)1999)

» adds security and remote configuration capabilitiesadds security and remote configuration capabilities

““Parties” (SNMP v2)Parties” (SNMP v2) Defined in SNMPv2 as logical SNMPv2 entities Defined in SNMPv2 as logical SNMPv2 entities

that can initiate or receive SNMPv2 that can initiate or receive SNMPv2 communication. Components:communication. Components:– a single, unique party identitya single, unique party identity– a logical network locationa logical network location– a single authentication protocola single authentication protocol– a single privacy protocola single privacy protocol

SNMPv2 messages communicated between SNMPv2 messages communicated between two partiestwo parties

SNMPv2 entity can define multiple parties, SNMPv2 entity can define multiple parties, each with different parameterseach with different parameters– e.g. different parties can use different authentication e.g. different parties can use different authentication

and/or privacy protocolsand/or privacy protocols

Controlling Flow of DataControlling Flow of Data

Data flow management built into protocolData flow management built into protocol Two main types: SYNCHRONOUS or Two main types: SYNCHRONOUS or

ASYNCHRONOUSASYNCHRONOUS– Synchronous:Synchronous:

» sent as a continuous flowsent as a continuous flow

» uses time signals to control flowuses time signals to control flow

– Asynchronous:Asynchronous:» sent as packetssent as packets

» next packet not sent until acknowledgement from receivernext packet not sent until acknowledgement from receiver

source sink

Data Routing TechnologiesData Routing Technologies Connection-Oriented (e.g. TCP use for Connection-Oriented (e.g. TCP use for

confirming receipt of a packet)confirming receipt of a packet)::– source, destination, and network topology all stored source, destination, and network topology all stored

in a databasein a database– single connection channel calculated from available single connection channel calculated from available

data using a routing algorithmdata using a routing algorithm– all data sent along that channelall data sent along that channel

Connectionless (e.g. IP):Connectionless (e.g. IP):– data sent in discrete units called packetsdata sent in discrete units called packets– each packet finds its own way through the network each packet finds its own way through the network

with the aid of routerswith the aid of routers

Connection-OrientedConnection-Oriented

All data follows the same routeAll data follows the same route

ConnectionlessConnectionless

Each packet follows its own routeEach packet follows its own route

Many other Technical Issues Many other Technical Issues resolved and became RFCs… resolved and became RFCs… Network Managers today don’t need to worry Network Managers today don’t need to worry

about developing their own protocolsabout developing their own protocols– so many have been developed…so many have been developed…

They do need to know what is out there, and They do need to know what is out there, and what it does…what it does…– RFC’s provide an exhaustive list of any “open RFC’s provide an exhaustive list of any “open

source” protocols proposed for Internet use since source” protocols proposed for Internet use since 19691969

– RFCs therefore hugely influential… in most cases RFCs therefore hugely influential… in most cases implementations available for popular operating implementations available for popular operating systemssystems

Less Technical Aspects of Less Technical Aspects of Network ManagementNetwork Management

Less technical because management is done Less technical because management is done at the desktop using “wizards”:at the desktop using “wizards”:– Fault ToleranceFault Tolerance– User ManagementUser Management– Control of user access to files & servicesControl of user access to files & services– Server ManagementServer Management– LAN managementLAN management– Multiple-site managementMultiple-site management– Virtual Desktop ManagementVirtual Desktop Management

Fault ToleranceFault Tolerance

ALL network hardware and software ALL network hardware and software should have a backup!!should have a backup!!

In case things go wrong...In case things go wrong...

User ManagementUser Management

More associated with “administration”More associated with “administration”– can also be technicalcan also be technical

Involves:Involves:– putting new users on the systemputting new users on the system– allocating users to groupsallocating users to groups– Making sure groups have appropriate Making sure groups have appropriate

network rights and privilegesnetwork rights and privileges

User Access ControlUser Access Control

At least 2 level access e.g. At least 2 level access e.g. username/passwordusername/password

Usernames & passwords stored in an Usernames & passwords stored in an authentication databaseauthentication database– sensible use of passwords (fixed rules)sensible use of passwords (fixed rules)

Username linked to level of privilegeUsername linked to level of privilege System must use a file system that System must use a file system that

includes file/folder level access controlincludes file/folder level access control

File SecurityFile Security No file security at all by default with DOS & No file security at all by default with DOS &

Windows, until Vista arrived…Windows, until Vista arrived… General principle not to allow users access to General principle not to allow users access to

files/folders they should not need to usefiles/folders they should not need to use Number of types of access:Number of types of access:

– e.g. read, execute, write, change, full controle.g. read, execute, write, change, full control

Files can also be remotely accessed through Files can also be remotely accessed through shares or a network directoryshares or a network directory

Server(s) ManagementServer(s) Management

Active Directory on a Windows networkActive Directory on a Windows network– Controlling user loginControlling user login– Controlling network assetsControlling network assets– Controlling access to server resourcesControlling access to server resources

Managing primary storageManaging primary storage– memory…. (largely automatic)memory…. (largely automatic)

Secondary storageSecondary storage– especially hard diskespecially hard disk

LAN ManagementLAN Management Active Directory (Windows) manages a Active Directory (Windows) manages a

domaindomain– includes servers, clients, users, and connections includes servers, clients, users, and connections

between all of thesebetween all of these– includes a range of other network services :includes a range of other network services :

» printingprinting» applicationsapplications» web accessweb access» file accessfile access

A Client uses services PROVIDED the A Client uses services PROVIDED the current user is given authority by active current user is given authority by active directorydirectory

Client-Server Networks on Client-Server Networks on Multiple SitesMultiple Sites

Multiple domainsMultiple domains Trust relationships between domainsTrust relationships between domains Inter-domain link:Inter-domain link:

– via telecoms line (expensive)via telecoms line (expensive)– via Internet (v. cheap!)via Internet (v. cheap!)– also needs a routeralso needs a router– if domains use different protocols, and/or if domains use different protocols, and/or

NOSs, gateway neededNOSs, gateway needed

Operating Systems serving Operating Systems serving Virtual DesktopsVirtual Desktops

A case of “back to the future”A case of “back to the future” Before the PC (“fat client”), network users Before the PC (“fat client”), network users

didn’t have local processingdidn’t have local processing– everything was centralised on the server(s)everything was centralised on the server(s)

The current trend is for “thin clients” where a The current trend is for “thin clients” where a whole desktop environment provided by the whole desktop environment provided by the server fits into an actual desktopserver fits into an actual desktop– Increased centralisation again on the serverIncreased centralisation again on the server

Why? Suggestions? In groups….Why? Suggestions? In groups….

Issues in client-server Issues in client-server networkingnetworking

Which NOS?Which NOS? Which protocol?Which protocol? How server security?How server security? Which Internet connectivity Which Internet connectivity

method/partner?method/partner? Communications within client-Communications within client-

server applicationsserver applications Thick or thin clients?Thick or thin clients? Network naming system? etc…Network naming system? etc…

Network Operating Systems Network Operating Systems (NOS) for client-server networks(NOS) for client-server networks

Three categories of product:Three categories of product:– Unix/Linux - established late 1970sUnix/Linux - established late 1970s

» many different proprietary versionsmany different proprietary versions» versions “free” to download but COMPLEXversions “free” to download but COMPLEX

– NetWare - established late 1980sNetWare - established late 1980s» best solution for most networks until Internet access became best solution for most networks until Internet access became

an issue. End up joining forces with Red Hat (Linux)an issue. End up joining forces with Red Hat (Linux)

– Windows NT/2000x - established mid/late Windows NT/2000x - established mid/late 1990s1990s

» became a popular rival to Netware largely because TCP/IP was became a popular rival to Netware largely because TCP/IP was packaged with it, and there was HUGE demand for Internet packaged with it, and there was HUGE demand for Internet access. Became the preferred product to Netware by 1997/8access. Became the preferred product to Netware by 1997/8

Summary: Why Network?Summary: Why Network?

Share resourcesShare resources Share dataShare data Authorise usersAuthorise users Keep data secureKeep data secure Manage resources remotelyManage resources remotely Allow all users Internet/email accessAllow all users Internet/email access

Summary: Why not network?Summary: Why not network?

No infrastructure initial & maintenance costNo infrastructure initial & maintenance cost No sharing neededNo sharing needed No risking sensitive dataNo risking sensitive data

– unless copied directly from machine or machine unless copied directly from machine or machine stolen!stolen!

Resources managed and maintained Resources managed and maintained individuallyindividually

No email/Internet access neededNo email/Internet access needed

Rest of this Course… Rest of this Course…

Will focus on network and user management Will focus on network and user management issues with a particular operating systemissues with a particular operating system– Windows 2003Windows 2003

Many issues present themselves on any Many issues present themselves on any networknetwork– most networks use Internet protocols to provide an most networks use Internet protocols to provide an

infrastructure e.g. TCP/IP, SNMPinfrastructure e.g. TCP/IP, SNMP– different operating systems have different features different operating systems have different features

for managing users and servicesfor managing users and services