MIB confusion - SNMP

This is a discussion on MIB confusion - SNMP ; Hi there, I've read through several docs and faqs but I'm still kinda fuzzy with the way MIB works. My understaning (correct me if i'm wrong) of a MIB is that its a collection of managed objects in a form ...

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  1. MIB confusion

    Hi there,

    I've read through several docs and faqs but I'm still kinda fuzzy with
    the way MIB works.

    My understaning (correct me if i'm wrong) of a MIB is that its a
    collection of managed objects in a form of database that tool(s)
    traverses when retrying to retrieve values, correct?

    Here's my confusion,

    1. what happens when NMS polls for an interface for traffic stats, how
    does MIB comes into play? does both NMS and AGENT need to have MIB
    loaded or only its only needed by the agents from which you're
    requesting queries?

    2. What if we take the above scenario but this time poll an interface
    via OID, does MIB is still needed?

    3. When is MIB not needed?

    4. How does NMS know to reference MIB database? Is MIB loaded being a
    part of NMS installation?

    5. Is there one MIB for all vendors?

    6. If there are different MIBs for different vendors then it could
    possible slow overall performance when there is a large collection of
    MIB files, correct?

    7. Can NMS or an AGENT poll without having MIB(s) loaded?

    8. Is MIB-2 (rfc1213) compatible with the current versions of SNMP
    (v1, v2c and v3) or does each version of snmp has its own MIB support
    or is MIB-2 ok to use?

    8. Does MIB-2 also cover ATM, Frame-Relay, BGP or do I need to load
    seperate MIBs for each of them? If so, how do I know if the devices or
    services that I'm monitoring requires MIBs and which one?

    Any good recommendation (urls) regarding MIBs will be nice.


    Appreciate any insight that can be offered.


    regards,
    vicky

  2. Re: MIB confusion

    In comp.protocols.snmp Vicky wrote:

    > I've read through several docs and faqs but I'm still kinda fuzzy with
    > the way MIB works.


    > My understaning (correct me if i'm wrong) of a MIB is that its a
    > collection of managed objects in a form of database that tool(s)
    > traverses when retrying to retrieve values, correct?


    The core of your confusion is that the term MIB means different things
    in different contexts:

    a) MIB - the set of managed objects implemented on a given device

    b) MIB - the formal description of managed objects (their data types,
    semantics, status and so forth) in the form of SMIv2 modules
    (hence people often use the term MIB module instead of the ambiguous
    term MIB in this case)

    > Here's my confusion,


    > 1. what happens when NMS polls for an interface for traffic stats, how
    > does MIB comes into play? does both NMS and AGENT need to have MIB
    > loaded or only its only needed by the agents from which you're
    > requesting queries?


    The agents implements objects in his MIB (a) - it generally does not
    have to have a MIB module at runtime. Management systems often need
    MIB modules at runtime to be able to resolve names to OIDs and so
    forth. However, it is also possible to write managers which do not need
    MIB modules at run time (in that case all necessary information is
    typically compiled into the manager).

    > 2. What if we take the above scenario but this time poll an interface
    > via OID, does MIB is still needed?


    Not necessarily.

    > 3. When is MIB not needed?


    If the management applications has all the information needed to
    do its job build into the application. For example, the little
    scli tool does quite
    some nice and useful stuff without every loading a MIB module at
    runtime.

    > 4. How does NMS know to reference MIB database? Is MIB loaded being a
    > part of NMS installation?


    MIB database is ambiguous, as it can either be the collection of MIB
    modules on the manager side of the set of object implementations on
    the agent side...

    > 5. Is there one MIB for all vendors?


    No. In case of (a), there is typically one MIB per agent. In case of
    (b), there are typically many MIB modules implemented by an agent
    or a manager and some might be standards, others might be proprietary.

    > 6. If there are different MIBs for different vendors then it could
    > possible slow overall performance when there is a large collection of
    > MIB files, correct?


    If you choose the right data structures, then the lookups should be
    fast independent how many definitions have been loaded from MIB modules.
    And you can cache results and on the extreme end even compile the info
    into the program to achieve a true constant lookup time.

    > 7. Can NMS or an AGENT poll without having MIB(s) loaded?


    Yes (I assume you mean MIB modules here).

    > 8. Is MIB-2 (rfc1213) compatible with the current versions of SNMP
    > (v1, v2c and v3) or does each version of snmp has its own MIB support
    > or is MIB-2 ok to use?


    The MIB in RFC 1213 has been broken into pieces. In general, MIBs work
    with any version of SNMP (except that some SMIv2 constructs such as
    Counter64 objects can not be accessed with SNMPv1).

    > 8. Does MIB-2 also cover ATM, Frame-Relay, BGP or do I need to load
    > seperate MIBs for each of them? If so, how do I know if the devices or
    > services that I'm monitoring requires MIBs and which one?


    There are separate MIB modules for ATM, BGP, ... The second question is
    harder to answer since there is not single standardize mechanism.
    Typically, a NMS supports specific MIB modules (that is code to manage
    boxes implementing say the FOO-MIB has been written) and there exists
    some probing code to figure out whether a box supports the FOO-MIB.
    In principle, you could load formal definitions of an agent's
    capabilities, but this does not seem to be used in practice (since
    most implementations do not support this).

    > Any good recommendation (urls) regarding MIBs will be nice.


    I think has pointers to tutorials as well
    as an online repository of standardized MIBs.

    /js

    --
    Juergen Schoenwaelder International University Bremen
    P.O. Box 750 561, 28725 Bremen, Germany

  3. Re: MIB confusion

    Search for the shareware software called getif . It is a MIB browser
    amongst other things, and will be able to show you the MIB. There are only
    a few MIB trees, and in practical terms only one has useful branches, of
    which one is RFC1213, a few branches in). It will allow you to expand and
    contract MIB levels of the tree just like folders on the Windows Explorer.
    You will find that one branch is called 'enterprises' (5 branches in !) ,
    and on this branch are all of the vendors MIBS (a complete list is very very
    long, and yes, the branch 'numbers' which make up the OIDs are managed to
    the extent that the enterprise numbers at least are assigned by an
    authority). Each vendor then creates more branches, subbranches, etc..
    There is quite a difference between what you'll see under the "Cisco" or
    "Microsoft" branches versus what would appear under a small, single product
    companies name. The software comes with a bunch of 'MIBs' and there are
    packages of enterprise MIBs to load.

    Dave

    "Vicky" wrote in message
    news:5bd08c5b.0402201223.3c8229e@posting.google.co m...
    > Hi there,
    >
    > I've read through several docs and faqs but I'm still kinda fuzzy with
    > the way MIB works.
    >
    > My understaning (correct me if i'm wrong) of a MIB is that its a
    > collection of managed objects in a form of database that tool(s)
    > traverses when retrying to retrieve values, correct?
    >
    > Here's my confusion,
    >
    > 1. what happens when NMS polls for an interface for traffic stats, how
    > does MIB comes into play? does both NMS and AGENT need to have MIB
    > loaded or only its only needed by the agents from which you're
    > requesting queries?
    >
    > 2. What if we take the above scenario but this time poll an interface
    > via OID, does MIB is still needed?
    >
    > 3. When is MIB not needed?
    >
    > 4. How does NMS know to reference MIB database? Is MIB loaded being a
    > part of NMS installation?
    >
    > 5. Is there one MIB for all vendors?
    >
    > 6. If there are different MIBs for different vendors then it could
    > possible slow overall performance when there is a large collection of
    > MIB files, correct?
    >
    > 7. Can NMS or an AGENT poll without having MIB(s) loaded?
    >
    > 8. Is MIB-2 (rfc1213) compatible with the current versions of SNMP
    > (v1, v2c and v3) or does each version of snmp has its own MIB support
    > or is MIB-2 ok to use?
    >
    > 8. Does MIB-2 also cover ATM, Frame-Relay, BGP or do I need to load
    > seperate MIBs for each of them? If so, how do I know if the devices or
    > services that I'm monitoring requires MIBs and which one?
    >
    > Any good recommendation (urls) regarding MIBs will be nice.
    >
    >
    > Appreciate any insight that can be offered.
    >
    >
    > regards,
    > vicky




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