Chapter 8 slides, 2nd edition by VWycS7P


									Chapter 3 outline
 What is network management?
 Internet-standard management framework
    Structure of Management Information: SMI
    Management Information Base: MIB
    SNMP Protocol Operations and Transport Mappings
    Security and Administration

 ASN.1
 Network management in the real world

                                                 CS457/546a   1
      Rehash: Stages of Management
 What have we seen so far to assist in the
  different stages of network management?
Policy formulation:
   Not much …
   It is largely up to human administrators to decide on
    policies dictating how their networks should operate.
   These administrators might base decisions on
    monitored data and analyses though.
   Can largely be handled with SNMP (SNMP get
    requests and traps) and other tools.
   Human administrators still have decisions to make:
    what to monitor, how often, polling or trap-driven
    management, and so on.                     CS457/546a   2
       Rehash: Stages of Management
 Analysis:
   Again, not much …
   It is largely up to human administrators to
    analyze management data on their own and
    develop their action plans for control.
   Automation will help, but this is not ready yet.
   In the mean time, tools to better represent monitored
    management information would be a great help.
 Control:
    Can largely be handled with SNMP (through set
     requests) and other tools.
    Some manual control is unavoidable.
                                             CS457/546a   3
      Rehash: Stages of Management
 So, in summary …
 What do we have?
  A  basic understanding of what network
    management is all about.
   Mechanisms to support monitoring and control
    operations for network management. (SNMP)
 What do we need?
   Decision making processes for policy formulation
    and for analyses to maintain network operations.
   Tools to make this decision making easier.

                                            CS457/546a   4
      Network Management In Theory
 There is nothing magical about computer
  networks, and there is nothing to be afraid of.
   Despite the fact that people built them, they
    tend to run in a logical fashion.
   The problem is that the complexity of our
    networks and their interdependencies tend to
    make finding this logic difficult.
 With determination, enough time, and the
  right tools for the job, anything can be done
  in managing computer networks.
 This, of course, is all “in theory”. Remember:
     In theory, theory and practice are the same.
      In practice, they’re not!               CS457/546a   5
      Network Management In Reality
What was wrong with our statement:
 “With determination, enough time, and the
 right tools for the job, anything can be done
 in managing computer networks.”
Well, a few things …
   There tends to be not enough time in practice to do
    everything. Consequently, tough decisions need to be
    made at some point.
   Finding the right tools is hard and expensive. Usually,
    there is no “right tool”, and you have to make do with
    several tools that do not quite do what is needed.
   There is often a lot of external pressure (from users,
    executives, and so on) that make doing what is needed
    for proper management difficult … and, sometimes,
    there is nothing you can do about it.     CS457/546a 6
       Network Management In Reality
What we are going to be studying from this:
 External pressures and constraints:
    What are the pressures and constraints faced
     when managing computer networks?
    What, if anything, can we do about them?
 Time issues:
   When faced with a lack of time, what can you
    do about network management?
   How do you decide what is important and what is not?
 Tools for the job:
   What tools are out there and what is needed?
   Remember that having good procedures and supports
    in place, keen analytical skills, and lots of experience
    are likely the best tools you can have! CS457/546a 7
Chapter 8 outline
 What is network management?
 Internet-standard management framework
    Structure of Management Information: SMI
    Management Information Base: MIB
    SNMP Protocol Operations and Transport Mappings
    Security and Administration

 ASN.1
 Network management in the real world
   External pressures and constraints
   Time issues
   Tools of the trade

                                                 CS457/546a   8
     External Pressures and Constraints
       Users            Presentation     Application
    Connections          Transport       Transport
                          Network         Network
                            Link            Link
       Cables             Physical        Physical
       Plenum           OSI Model      Internet Model
Network Control Model                       CS457/546a   9
       The Network Control Model
 Formulated by David Wiseman (aka Magi) as a
  way of demonstrating how network management
  is only partly a technical problem, with a lot of
  external factors without technical solutions.
   Senior management/executive issues.
   End user issues.
   Administrative authority issues.
   Ownership issues.

 In the end, only a small part of the world can be
  managed, while the rest of it has great
  influence on how that little bit of management
  can or cannot be done.
                                          CS457/546a   10
       The Network Control Model
 Technical religious issues are different from
  the religious issues normal people care about:
    emacs versus vi versus pico    C versus Lisp
    Linux versus Windows           Redhat versus Debian …
    PC versus Mac                  Gnome versus KDE
 Instead of using the right technology for the
  job, choices and decisions are based solely on
  personal beliefs and preferences.
 If senior management/executives are zealots of
  a particular technical religion, their demands
  could have a large impact on how the network
  can be management.                      CS457/546a 11
The Network Control Model

                            CS457/546a   12
         The Network Control Model
 Deals with social relations involving authority
  or power within or between organizations.
      For example, using one vendor’s equipment because
       their boss and your boss are golfing buddies.
 Unlike decisions based solely on technical
  religious grounds, political decisions have solid
  reasoning that can be expressed and understood
  by everyone (even if it is not agreed with).
 Politics from senior management/executives can
  also have a large impact on decisions made for
  network management.                     CS457/546a 13
      The Network Control Model
 Deals with issues surrounding money. These
  issues are usually pushed by senior management
  or executives, but everyone knows that their
  budget is ultimately limited.
 Unfortunately, this can have a large impact on
  what network management can be done and how.
   What hardware and software must be used.
   What upgrades can be afforded, and what must wait.
   What kind of staffing level can be supported.
   What kind of management tools can be afforded.
   How much time can be spent.             CS457/546a 14
The Network Control Model

                            CS457/546a   15
       The Network Control Model
 Ultimately, the network is being managed
  for their benefit, end users must be taken
  into consideration at some point.
 Sadly, users are surprisingly hard to deal with.
   They often do not have enough technical expertise.
   They are often totally unaware of the religious,
    political, financial, and technical reasons behind why
    things are done the way they are done.
   They often do not realize the magnitude of their
    requests, or if they do, they don’t seem to care.
 Nevertheless, network managers must deal with
  them and keep their needs, requests, and input
  in mind when managing the network. CS457/546a 16
The Network Control Model

                            CS457/546a   17
The Network Control Model

                            CS457/546a   18
The Network Control Model

                            CS457/546a   19
      The Network Control Model
 The realm of connections basically deals with
  whether the various parts of user applications
  can communicate with each other across a wide
  area network (WAN), like the global Internet.
 We are now getting to down to technical
  issues, but there are now also issues of
  administrative authority.
   A network manager only has authority over their
    local portion of the network, and no one else’s.
   Ultimately, this limits the amount of monitoring,
    analysis and control possible in management.
                                             CS457/546a   20
       The Network Control Model
 This deals with the services to support
  application communication in our network.
 Often, these services are not owned by your
  organization, even though it depends on them.
 Instead, they are provided by your network
  services provider (ISP in the Internet world).
   Rogers for your cable Internet service.
   Bell for your DSL Internet service (likely the case,
    even if you go through another company, because
    ultimately they get line access from Bell).
 Again, if you do not own the service, network
  management in this case can be difficult and
  quite limited.                       CS457/546a      21
        The Network Control Model
 Unless your environment is totally wireless, you
  also need worry about cable management.
     They can bend, break, degrade, and so on, so you need
      to worry about managing them as well.
 Some you own and have ready access to.
 Unfortunately, there are others that are not
  owned by you. Examples:
   The connections into your building.
   In some cases the wiring inside the building belongs
    to the installer, which can be a headache.
 This can pose further management problems.
                                             CS457/546a   22
       The Network Control Model
 The plenum refers to the place where cabling
  resides, or the air if you are going wireless.
 This can have separate ownership from the
  cables themselves, which adds another layer of
  complexity to things.
 Some times you might not have legal access.
   You might not own the property.
   You might own the property but not the mechanisms
    running the cable (telephone poles, for example).
   You might own it all but still not have legal access
    (for example, if your networking shares space with
    telephone lines or equipment).             CS457/546a 23
       The Network Control Model
What do we get from this model?
   Technical issues can be managed in our networks.
   Religious, political, financial, end user, authority, and
    ownership issues can greatly affect just what is
    managed, and how management can be done. These
    issues on their own cannot be easily managed.
If we cannot manage these pressures and
  constraints, what can we do then?
   Just understanding that they exist and expecting
    them can provide some help (and consolation).
   Recognizing how these issues appear in your
    particular organization and how they affect network
    management can also make things easier.
   Otherwise, there is not much else that
    can be done!                            CS457/546a 24
Chapter 8 outline
 What is network management?
 Internet-standard management framework
    Structure of Management Information: SMI
    Management Information Base: MIB
    SNMP Protocol Operations and Transport Mappings
    Security and Administration

 ASN.1
 Network management in the real world
   External pressures and constraints
   Time issues
   Tools of the trade

                                                 CS457/546a   25
                Not Enough Time
 More often than not, there is too much network
  management work to accomplish and not enough
  time to do it all properly.
     This is even after we take into all of the constraints
      we just talked about, which on their own limit what
      management is capable of doing.
 In such cases, we have some tough decisions
  that we need to make.
   What is important and what is not?
   What can we afford to allow to fail?
   Which policies of our network operations will we allow
    ourselves to violate on a transient basis? Which
    policies will we allow ourselves to ignore on a more
    permanent basis?                           CS457/546a 26
Not Enough Time

                  CS457/546a   27
Time Factors: The Size of the Network
 The question is: is the network manageable
  considering its size and scale?
 If the network is not big enough:
      It is too small to justify additional personnel (or
       other resources), so you are on your own.
 If the network is too large:
    It is too big for whatever personnel you are already
     allocated, and getting more will still be difficult.
     (The bottom line is that network infrastructure
     support on its own does not generate money!)
 Either way, you are in trouble.
    You do not have enough hours to do everything you
     wish you could, or even just those things you think
     you should.                              CS457/546a 28
   Time Factors: The Volume of Data
 Supposing that the network is of manageable
  size, what will you do with the volume of data
  generated in monitoring it?
      If even a fraction of management agents report a
       fraction of data available in their MIBs, it will still be
       an immense amount of data.
 You are left with some tough questions:
    What do you do with all of that data?
    How much time would it take to summarize it?
    How would you summarize it? (Without leaving out
     important events or important devices?)
    How much time would it take to analyze it?
 And, all of this takes more precious time!
                                                  CS457/546a   29
          Time Factors: Complexity
 There is a lot in a network a manager needs to
  understand and appreciate:
     All the hardware, all the software, the network
      configuration, the various network protocols in use,
      user needs, application needs, and so on.
 The management data available is also complex.
   What    to monitor, how often, what to watch for,
      and what to do when certain events occur.
 Sorting through all of this complexity
  and making sense of things takes time to
  do properly.
                                               CS457/546a   30
Time Factors: Pressures and Constraints
 While generally making network management
  more difficult, the pressures and constraints
  discussed earlier also tend to make things
  easier time-wise.
 Why?
   Sometimes you will not be given choices. There are
    some things you must do, and other things that you
    cannot do. A lack of choices can make things easier,
    although uncomfortable.
   Because responding to problems involves more than
    just technical issues. For example, some users are
    more important than others. This makes choices
    easier to make sometimes.               CS457/546a 31
        Determining What is Important
 It is necessary to recognize that a network
  manager simply cannot deal with everything.
      So, managers must be able to decide what is most
       important, and concentrate on these things.
 Questions to ask to find out what is important:
   What are the most mission critical applications, pieces
    of hardware, network links, protocols, users, and so on?
   What is the most feeble network link, piece of
    hardware, piece of software, and so on?
   Where is failure likely? Where is failure noticeable?
   What were you told was important?
 Even now, the list is likely too large to handle,
  especially if you were told to do too many things.
                                               CS457/546a   32
Determining What Can Be Allowed To Fail
 We still need to trim our list of management
  tasks to something that can be accomplished.
 To do this, you need to determine:
   What can be allowed to break.
   What things do not need to be prevented before
    users wake up and notice them.
   What things are not likely to be noticed if they break.
   Which thing are “unlikely enough” to fail that we
    can reasonably afford to ignore them.
 Then, you ignore them and hope they do not fail.
   You watch them only if time allows or if failures
    demand that you do.
                                              CS457/546a   33
Determining What Can Be Allowed To Fail
 What questions do you ask to determine this?
   What does not affect the network itself?
   What is extremely unlikely to fail?
   What will not be missed (immediately) if it fails?
   What are others inside or outside of your organization
    already monitoring or managing?
   What are others already responsible for?
   What cannot cause damage?

 Yes, you are choosing what you ignore or, at
  least, what you do not actively manage.
     But, you are doing it sensibly and not randomly
      or ignorantly.
                                                CS457/546a   34
             The Hard Decisions
 How do you decide what is truly important?
   You understand your network.
 How do you decide what can be safely ignored?
   You understand your network.
 What do you do when nothing is unimportant?
   Run away screaming, and look for a new job!
 Whatever the answers, two things to remember:
   Things change. You have to keep asking these
    questions and re-evaluating priorities and procedures.
   Initial management setup is crucial. This determines
    what is initially possible and impossible. And, guess
    what? Your initial choice is likely what you will be
    stuck with forever, so make sure it is GOOD! (You
    won’t have time to it change later!)       CS457/546a 35

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