Thursday, November 15, 2007

tcp/ip overview 14th nov' 2007

course: refresher course on intranet applications with java
venue: academic staff college, jntu kukkatpally, hyderabad


TCP/IP
Transmission Control Protocol / Internet Protocol
• Rajesh Kulkarni
TCP/IP & OSI
• In OSI reference model terminology -the TCP/IP protocol suite covers the network and transport layers.

• TCP/IP can be used on many data-link layers (can support many network hardware implementations).
Internet Protocol
The IP in TCP/IP
• IP is the network layer
• packet delivery service (host-to-host).
• translation between different data-link protocols.
IP Datagrams
• IP provides connectionless, unreliable delivery of IP datagrams.
• Connectionless: each datagram is independent of all others.
• Unreliable: there is no guarantee that datagrams are delivered correctly or even delivered at all.
IP Addresses
• IP addresses are not the same as the underlying data-link (MAC) addresses.

Why ?
IP Addresses
• IP is a network layer - it must be capable of providing communication between hosts on different kinds of networks (different data-link implementations).
• The address must include information about what network the receiving host is on. This is what makes routing feasible.
IP Addresses
• IP addresses are logical addresses (not physical)
• 32 bits.
• Includes a network ID and a host ID.
• Every host must have a unique IP address.
• IP addresses are assigned by a central authority (American Registry for Internet Numbers for North America).

The four formats of IP Addresses

Class A
 128 possible network IDs
 over 4 million host IDs per network ID
Network and Host IDs
• A Network ID is assigned to an organization by a global authority.

• Host IDs are assigned locally by a system administrator.

• Both the Network ID and the Host ID are used for routing.
IP Addresses
• IP Addresses are usually shown in dotted decimal notation:
1.2.3.4 00000001 00000010 00000011 00000100
• cs.rpi.edu is 128.213.1.1
10000000 11010101 00000001 00000001
Host and Network Addresses
• A single network interface is assigned a single IP address called the host address.
• A host may have multiple interfaces, and therefore multiple host addresses.
• Hosts that share a network all have the same IP network address (the network ID).
Subnet Addresses
• An organization can subdivide it’s host address space into groups called subnets.
• The subnet ID is generally used to group hosts based on the physical network topology.
Subnetting
Subnetting
• Subnets can simplify routing.
• IP subnet broadcasts have a hostID of all 1s.
• It is possible to have a single wire network with multiple subnets.
Mapping IP Addresses to Hardware Addresses
• IP Addresses are not recognized by hardware.
• If we know the IP address of a host, how do we find out the hardware address ?
• The process of finding the hardware address of a host given the IP address is called
Address Resolution
Reverse Address Resolution
• The process of finding out the IP address of a host given a hardware address is called
Reverse Address Resolution

• Reverse address resolution is needed by diskless workstations when booting (which used to be quite common).
ARP
• The Address Resolution Protocol is used by a sending host when it knows the IP address of the destination but needs the Ethernet (or whatever) address.
• ARP is a broadcast protocol - every host on the network receives the request.
• Each host checks the request against it’s IP address - the right one responds.
ARP (cont.)
• ARP does not need to be done every time an IP datagram is sent - hosts remember the hardware addresses of each other.
• Part of the ARP protocol specifies that the receiving host should also remember the IP and hardware addresses of the sending host.
ARP conversation
RARP conversation
Services provided by IP
• Connectionless Delivery (each datagram is treated individually).
• Unreliable (delivery is not guaranteed).
• Fragmentation / Reassembly (based on hardware MTU).
• Routing.
• Error detection.
IP Datagram
IP Datagram Fragmentation
• Each fragment (packet) has the same structure as the IP datagram.
• IP specifies that datagram reassembly is done only at the destination (not on a hop-by-hop basis).
• If any of the fragments are lost - the entire datagram is discarded (and an ICMP message is sent to the sender).
IP Flow Control & Error Detection
• If packets arrive too fast - the receiver discards excessive packets and sends an ICMP message to the sender (SOURCE QUENCH).
• If an error is found (header checksum problem) the packet is discarded and an ICMP message is sent to the sender.
ICMP
Internet Control Message Protocol
• ICMP is a protocol used for exchanging control messages.
• ICMP uses IP to deliver messages.
• ICMP messages are usually generated and processed by the IP software, not the user process.
ICMP Message Types
• Echo Request
• Echo Response
• Destination Unreachable
• Redirect
• Time Exceeded
• Redirect (route change)
• there are more ...
IP/BYE-BYE
• IP/BYE-BYE is a lecture protocol used to signal the class that we have just finished our discussion of IP - the network layer of TCP/IP.
• The appropriate response to an IP/BYE-BYE request is immediate applause, although simply opening your eyes is enough (known as a WAKEUP response).
Transport Layer & TCP/IP
Q: We know that IP is the network layer - so TCP must be the transport layer, right ?
A: No… well, almost.

TCP is only part of the TCP/IP transport layer - the other part is UDP (User Datagram Protocol).

UDP User Datagram Protocol
• UDP is a transport protocol
• communication between processes

• UDP uses IP to deliver datagrams to the right host.
• UDP uses ports to provide communication services to individual processes.
Ports
• TCP/IP uses an abstract destination point called a protocol port.
• Ports are identified by a positive integer.
• Operating systems provide some mechanism that processes use to specify a port.
Ports
UDP
• Datagram Delivery
• Connectionless
• Unreliable
• Minimal
TCP
Transmission Control Protocol
• TCP is an alternative transport layer protocol supported by TCP/IP.
• TCP provides:
• Connection-oriented
• Reliable
• Full-duplex
• Byte-Stream
Connection-Oriented
• Connection oriented means that a virtual connection is established before any user data is transferred.
• If the connection cannot be established - the user program is notified (finds out).
• If the connection is ever interrupted - the user program(s) is finds out there is a problem.
Reliable
• Reliable means that every transmission of data is acknowledged by the receiver.
• If the sender does not receive acknowledgement within a specified amount of time, the sender retransmits the data.
Byte Stream
• Stream means that the connection is treated as a stream of bytes.

• The user application does not need to package data in individual datagrams (as with UDP).
Buffering
• TCP is responsible for buffering data and determining when it is time to send a datagram.

• It is possible for an application to tell TCP to send the data it has buffered without waiting for a buffer to fill up.
Full Duplex
• TCP provides transfer in both directions (over a single virtual connection).

• To the application program these appear as 2 unrelated data streams, although TCP can piggyback control and data communication by providing control information (such as an ACK) along with user data.
TCP Ports
• Interprocess communication via TCP is achieved with the use of ports (just like UDP).

• UDP ports have no relation to TCP ports (different name spaces).
TCP Segments
• The chunk of data that TCP asks IP to deliver is called a TCP segment.

• Each segment contains:
• data bytes from the byte stream
• control information that identifies the data bytes
TCP Segment Format
Addressing in TCP/IP
• Each TCP/IP address includes:
• Internet Address
• Protocol (UDP or TCP)
• Port Number
TCP vs. UDP
Q: Which protocol is better ?
A: It depends on the application.

TCP provides a connection-oriented, reliable, byte stream service (lots of overhead).

UDP offers minimal datagram delivery service (as little overhead as possible).
TCP/IP Summary
• IP: network layer protocol
• unreliable datagram delivery between hosts.
• UDP: transport layer protocol
• unreliable datagram delivery between processes.
• TCP: transport layer protocol
• reliable, byte-stream delivery between processes.

Intranet

topic: intranet
course:refresher course on intranet applications with java at jntu kukkatpally, hyderabad
audience: professors from jntu, engineering colleges.
venue: academic staff college jntu hyderabad


What is an Intranet?
What is an Intranet?
• A private network; a LAN or WAN.
• A website on a private network, often called a Corporate Portal.
What can an Intranet display?
• Practically anything!
– documents
– forms
– charts and graphs
– pictures & scanned images
– databases
– downloadable files
What can an Intranet display?
• Relatively static information
– benefits descriptions
– policies & procedures
– forms
– org charts
– newsletters
– document templates
– facility locations & maps
What can an Intranet display?
• Somewhat dynamic information
– phone & staff lists
– internal job postings
– driver signup lists
– run or line schedules
– turn-by-turn route directions
– project summaries and schedules
What can an Intranet display?
• Highly dynamic information
– daily performance metrics (rollout, attendance, stock levels, etc.)
– vehicle status & location
– on-board equipment monitoring alerts
– individual employee data (sick leave & vacation accrual, etc.)
How do I sell the idea?
• Operations:
– better, faster access to data
• Finance:
– Web-based reporting & OLAP tools allow users to query across all enterprise databases
• Information Services:
– reduced desktop support costs for browser-based applications
– a central source for user self-help (online training, User Guides, FAQs)
How do I sell the idea?
• Management:
– faster, easier access to all enterprise data for local, remote and mobile users
– reduced employee training costs due to a single, unified application interface
• All areas:
– post the material and the answers that people ask for over and over
How do I build an Intranet?
• The free, 10-minute, no-excuses Intranet

• The cheap, D-I-Y Intranet

• The scalable, Enterprise solution


How do I build an Intranet?
• The free, 10-minute, no-excuses Intranet
– Intranets.com, eGroups.com
• The cheap, D-I-Y Intranet
– a server, an HTML editor, and an Intern
• The scalable, Enterprise solution
– Xerox DocuSource, Plumtree, Hummingbird, WebUpdate or the like
A free intranets.com Intranet
AC Transit’s D-I-Y Intranet
How do I get users to visit?
• Start with a handful of things staff are always looking for:
– phone lists & org charts
– benefits info and health plan contacts
– internal job postings
• For some of these, make the Intranet the only place to get them
• Always, always keep it current
How will I know it’s a success?
• When you no longer have to explain what an Intranet is
• When you don’t have to go looking for content, it finds you
• When it’s the first place people look for information!
Driving the Intranet

Is your intranet
business positive?
Is your intranet business positive?
 Intranets can be a very effective strategic resource within an organisation
 An intranet can be a key business tool for achieving corporate goals
 The reality, however, is that many intranets are not currently delivering on this ideal
 This can be fixed
 By using appropriate techniques and approaches, an intranet can be made business positive
History of the intranet
 Most intranets have grown organically
 With no overall strategy or direction, individual additions have been made ad-hoc
 Common intranet problems:
• Unstructured, and inconsistent
• Out-of-date, inaccurate and incomplete
• Content authoring processes not working
• Information is hard to find
• Not widely used by staff
Bringing it into focus
 The first step to building a better intranet is determining a strategic plan
 This must be driven by staff needs
 The organisation also has requirements that
must be met

 Intranets are not a technology problem
 Much more important are people and processes
Improving intranet design
 There are a number of techniques that can be used to improve the design and structure of an intranet:

 information architecture
 usability
 content writing
 indexing

Beyond usable
 A good intranet is usable: information is easy to find, the intranet is well-structured, and consistent
 This is not enough
 An intranet can be perfectly designed, but if the content is not right, it is entirely useless
 An intranet must be useful: it meets the real needs of staff throughout the organisation
 There are a range of practical techniques for ensuring this
Intranet goals

Intranet goals
 Many intranets were established with a single goal:
“Deliver information effectively and efficiently to all staff”
 Most intranets have now met this goal, and yet are still not delivering real benefits
 An intranet must meet wider business goals to be effective
 These must be aligned with corporate strategies
 Good goals are a strategic “land grab”
Possible intranet goals
 Better communication
 Improve productivity
 Better decision making
 Enable feedback
 Facilitate business processes
 Meet budget
 Reduce need for support
 Reduce paper consumption
 Reduce e-mail overload
 Enhance collaboration
 Support knowledge sharing
 Build corporate identity
 Create a single culture
 Improve distribution of news
 Support systems integration
 Align with organisational strategy
 Facilitate change management
More intranet goals
 Provide a reference tool for staff
 Achieve business improvements
 Provide best practice information
 Support geographically isolated staff
 Support skills sharing
 Support networking
 Improve public image
 Help staff to do their jobs
 Support staff orientation
 Improve information accessibility
 Support training
 Provide social environment
 Become a focus for organisational systems
 Act as an archive
 Support business processes
Metrics & measures
 Metrics are a way of defining what the intranet will achieve, and whether it met those goals
 Also known as:
• Measures
• Key Performance Indicators (KPIs)
 Often, but not always, numerical
 Increasingly important in an environment of tight budgets
 Key part of “Balanced Scorecard”
Benefits of metrics
Allows:
 Targets to be set
 Success to be assessed
 ROI to be estimated
 Ongoing viability to be tracked
 Lessons to be learnt
Some sample metrics
 System usage
 Number of users
 Information quality
 Information currency
 User feedback
 Maintenance costs
 Staff efficiency
 Printing costs
 Distributed authoring
 Process efficiency
 Transaction costs
 Product sales
 Customer satisfaction
 Consistency of advice
 Call handling time
 Success stories, anecdotes
 Staff morale
 Cultural change
 Staff learning
Guidelines & tips
 Business-focused metrics are best
 Determine a baseline
 Automate measures
 Measure the right things
 Less, not more
 Recognise the impact on staff
 Re-evaluate measures every 6-12 months
Identifying staff needs

Identifying needs
 An intranet will only be used if it meets actual
staff needs
 It must also match organisational goals and strategies
 Don’t ask staff what they need
 Even if they want to, they can’t describe what they actually use and need
 Use structured investigation methods

Structured techniques
 Reviewing the existing environment
 Expert site review
 Focus groups & surveys
 Usage & search statistics
 Stakeholder interviews
 Workplace observation
 Process & knowledge mapping
Beyond surveys & focus groups
There are two traditional investigation methods:
 Focus groups
• unstructured
• often does not reach consensus
• can be dominated by a few vocal members
 Surveys
• staff will tell you what you want hear
• results don’t match reality
• difficult to create, time-consuming to analyse
Stakeholder interviews
 Conduct stakeholder interviews with actual users
 Focus on jobs, not intranet, with questions like:
• What are the main activities that make up your job?
• Who do you communicate most frequently with?
• What information do you use during a normal working day?
• Where do you obtain this information from?
• How do you find out about what’s happening in the organisation?
 This is a simple form of knowledge mapping
 Can be the first time staff are actually listened to
Workplace observation
 Involves going ‘out into the field’, and watching staff conduct their normal activities
 It is a holistic approach that can identify many issues and needs
 Need to spend enough time to ‘blend in’
 Must be done ethically
 Very effective in a ‘front line’ environment, such as call centres, branches, etc.
Bringing it all together

Bringing it all together
 Having a set of business-focused goals ensures that the intranet is positioned as a strategic asset
 Goals also clarifies the direction to take
 Taking a step back, and spending the time to understand staff needs is always enlightening
 In this way, the intranet is driven from the ‘top down’ and the ‘bottom up’
 This is much more effective than ‘sitting in a room and thinking hard about the intranet’
Bringing it all together (cont)
 Maintaining an intranet is not enough
 Improving structure, design & content of a site can be pointless if the site is not delivering the resources that staff need
 There are thousands of ‘good ideas’ for an intranet
 By understanding staff needs and intranet goals, priorities can be set, and resources applied effectively
 This ensures that the intranet is business positive
Australian KM, CM & intranet groups
 groups.yahoo.com/group/intranet-peers
A peer group of hands-on intranet managers in the public sector. Online list and forums in a major capital city every quarter.
 groups.yahoo.com/group/NSW-KM-Forum-Announce
Announce list for NSW KM Forum meetings held in Sydney, 1st Thursday of each month
 groups.yahoo.com/group/act-km
Australian mailing list for knowledge management
Questions?

 Visit www.steptwo.com.au for more content management and intranet whitepapers

What’s Wrong with Intranets:
Users’ perspective
 Users can’t find what they need (information architecture problem)
• “How come I didn’t know your department was developing a product similar to ours?”
• “Why couldn’t we find any relevant case studies to show that important prospect?”
• “Why do our sales and support staff keep giving our customers inconsistent information?”
What’s Wrong with Intranets:
Owners’ perspectives
 Owners are overwhelmed (enterprise management problem)
• Content management pressures
• Resource allocation
• Technology selection
• Challenge of creating a unified intranet in a highly distributed environment
Users’ Problems
+ Owners’ Problems
= Enterprise IA (EIA)
The EIA Framework
Seven issues
• EIA governance: how the work and staff are structured
• EIA services: how work gets done in an enterprise environment
• EIA staffing: who handles strategic and tactical efforts
• EIA funding model: how it gets paid for
• EIA marketing and communications: how it gets adopted by the enterprise
• EIA workflow: how it gets maintained
• EIA design and timing: what gets created and when
EIA Governance:
Questions
 What sort of individuals or group should be responsible for the EIA?
 Where should they be located within the organization? How should they address strategic issues? Tactical issues?
 Can they get their work done with carrots, sticks, or both as they try to work with somewhat autonomous business units?
EIA Governance:
A separate business unit 1/2
 Logical outgrowth of
• Web or portal team
• Design or branding group
• E-services, e-business or e-commerce unit
 Goals
• Ensure that IA is primary goal of the unit
• Retain organizational learning
• Avoid political baggage
• Maintain independence
EIA Governance:
A separate business unit 2/2
 Ambitious, fool-hardy, unrealistic? Necessary!
• Models of successful new organizational efforts often start as separate entities
• Alternatives (none especially attractive)
• Be a part of IT or information services
• Be a part of marketing and communications
• Be a part of each business unit
EIA Governance:
Balancing strategic and tactical
 Strategic: Model on Board of Directors
• 5-7 representatives of key constituencies
• Track record with successes, mistakes with organization’s prior centralization efforts
• Mix of visionaries, people who understand money
 Tactical: Start with staff who “do stuff”
• Extend as necessary by outsourcing
• Enables logical planning of hiring and use of consultants and contractors
EIA Governance:
Board of directors 1/2
 Goals
• Understand the strategic role of information architecture within the enterprise
• Promote information architecture services as a permanent part of the enterprise’s infrastructure
• Align the group and its services with those goals
• Ensure the group’s financial and political viability
• Help develop the group’s policies
• Support the group’s management
 Makeup
• Draw first from effective leaders
• Then from major units that would be strategic partners
EIA Governance:
Board of directors 2/2
 Qualities
• Experience and duration in the enterprise
• Wide visibility and extensive network
• Can draw on institutional memories and experiences
• Track record of involvement with successful initiatives
• Entrepreneurial (can read and write a business plan)
• Experienced with centralization efforts
• Does not shy away from political situations
• Can “sell” a new concept and find internal funding
• Is like the people you need to “sell” to
• Has experience with consulting operations
• Has experience negotiating with vendors
EIA Services:
Questions
 What should a team responsible for EIA actually do?
 How do their “services” fit with work that happens within business units? Or with outside contractors and consultants?
 What kind of people should manage these efforts?
 How do IA generalists and specialists fit together?
EIA Services:
From overwhelming to digestible
EIA Services:
Modular service plan
 Avoid “monolithic” approach: “Hi, we’re the EIA team and we’re here to help… and we’re going to centralize all of your information…”
 Break IA and CM into digestible, non-threatening tasks and sell those
• Allows you to divide and conquer clients…
• …and helps you understand IA challenges better (e.g., applying metadata in a centralized environment)
EIA Services:
Potential service offerings 1/2
 User-oriented
• Persona and scenario development
• User testing and task analysis
• Search and server log analysis
 Content-oriented
• Content inventory and analysis
• Content evaluation and assessment
• Content model design
• Content development policy (creation, maintenance)
• Content weeding, ROT removal, and archiving
• Content management tool (acquisition, maintenance)
• Metadata development
• Metadata maintenance
• Manual tagging
• Automated categorization and classification
EIA Services:
Potential service offerings 2/2
 Context-oriented
• Business metrics development and analysis
• Internal marketing strategy and implementation
• Stakeholder and decision-maker interviews
• Business rules development (for best bets, content models, etc.)
 Production/Maintenance
• Template design and application
• Training
• Policy/procedure/standards development and acceptance
• Publicity of new/changed content
• Tool analysis/acquisition (CMS, search, portal)
• Quality control and editing
• Link checking
• HTML validation
• Liaison with visual design staff, IT staff, vendors
EIA Services:
Assessing departmental IA needs
EIA Services:
Basic & premium levels
EIA Services:
Phased demand for IA services
EIA Staffing:
Questions
 Who should be involved: in-house, consultant, contractor? What type of specialization should the staff have?
 Should they be centralized or located within business units or both?
EIA Staffing:
Tactical team 1/4
 Goals
• Delivers IA services to the enterprise in content, users, and context areas
• Implements the strategic team’s policies
• Works directly with clients to understand their needs and develop new services to meet those needs
EIA Staffing:
Tactical team 2/4
 Make-up driven by “market demand,” existing resources
 “Vertical” IA generalists: split between EIA project enterprise business units
 “Horizontal” IA specialists: “consultants” for both groups of generalists
• Tools (e.g., search, portal, CMS)
• Metrics
• Evaluation
• Metadata development
• XML and other markup languages
EIA Staffing:
Tactical team 3/4
EIA Staffing:
Tactical team 4/4
 Qualities for member of tactical team
• Entrepreneurial mindset
• Ability to consult (i.e., do work and justify IA and navigate difficult political environments)
• Willingness to acknowledge ignorance and seek help
• Ability to communicate with people from other fields
• Sensitivity to users’ needs
• …and know about IA and related fields
EIA Staffing:
Team Structure 1/2
EIA Staffing:
Team structure 2/2
EIA Funding Model:
Questions
 How should this group be funded?
 How should other expenses (e.g., software licenses) be covered? Charge-back fees for individual services? Flat “tax” paid by business units? Covered by general administration's tab? Some hybrid thereof?
 Should certain services be performed gratis, while others require payment?
EIA Funding Model:
Looking for inspiration
 Study the successes/failures of the enterprise’s other centrally funded services
 Possible plan
• Initially: “tax” on business units and/or “seed capital” from senior management
• Ultimately: self-funding (models: IT, HR, special projects)
 Key: funding should be from central group (e.g., senior management) or self-funded; else too much dependency on business units
EIA Funding Model:
Ensuring independence
 Potential models already in existence in the enterprise
• Charge-back
• Tax on business units
• Money from general fund
• Hybrids
 Charge-back model is attractive
• Increasing perceived value of IA by charging fees
• Compares well with duplicated expenses incurred by business units
EIA Funding Model:
Diversify revenue streams
EIA Marketing & Communications:
Questions
 How to position this work and the group that supports it: IA? User Experience? Web Design? How do these terms affect the scope of the work/charter of the group?
 How does a plan like this get “sold,” and to whom?
 Whose support is needed, and what tactics are useful in convincing them to support EIA work?
 How to prioritize which business units around the enterprise to work with?
EIA Marketing & Communications:
Positioning the EIA initiative
 Approaching “clients”
• No carrot or stick
• Offer services and consulting that save money, reduce tedium
 Branding: choose the term that is
• Hottest
• Has least baggage
• Steps on fewest toes
EIA Marketing & Communications:
Selling IA
 Concrete
• We can make work easier and save money for individual business units
• We can improve the user experience and build brand loyalty among customers, organizational loyalty among employees
• We can minimize the enterprise’s habit of purchasing redundant licenses and services
EIA Marketing & Communications:
One unit at a time
 Start with low-hanging fruit
• Killer content
• Plentiful or influential users
• Strategic value (business context)
 Determine current status of the “client”
• What are they doing now?
• What expertise is in-house?
• What relevant tools do they own (extend licenses)?
• Are they enlightened?
EIA Marketing & Communications:
Illustrating the concept
 Select an initial model for centralized approach that’s familiar, accessible
 Staff directory often the best
• Serves all enterprise users
• Useful, highly structured content which may have significant metadata, searching and browsing capabilities
• Has high value in context of the enterprise’s daily operations
EIA Design/Timing:
Questions
 An EIA design is an overwhelmingly large undertaking; how might it be broken into more digestible pieces?
 How should they be sequence: what makes sense to take on now, later, or perhaps not at all?
EIA Design/Timing:
Modular, phased
EIA Design/Timing:
3-6 years, not months
 Use early successes as models
 Anticipate greater centralization among and within business units over time
 Support different levels of centralization concurrently (Neanderthals coexist with Space Agers)
EIA Workflow:
Questions
 How does the content authoring and publishing process work now?
 Who and how many are involved?
 How can the group support that work, and determine the best mix of centralized and autonomous responsibilities within that workflow?
EIA Workflow:
Deconstruct, then assign
 Determine roles, then responsibilities among local and central units
 Strive for evolution toward centralization
EIA Framework:
Summary
 Entrepreneurial
• Services marketed to internal clients
• Goal of self-sustainability
 Modular
• Specific services, not full package
• Logical migration path
 Phased
• Projects that are low hanging fruit
• Selective roll-out