





Network Working Group                                      F. Kastenholz
Request for Comments: 1369                                  FTP Software
                                                            October 1992


                  Implementation Notes and Experience for
                         The Internet Ethernet MIB

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard.  Distribution of this memo is
   unlimited.

Table of Contents

   1. Introduction ................................................    1
   2. Observations ................................................    2
   3. Conclusions .................................................    3
   4. Final Action ................................................    4
   5. Implementation Data .........................................    5
   6. Security Considerations .....................................    7
   7. Author's Address ............................................    7

1.  Introduction

   The Ethernet MIB Working group has been tasked with the following two
   work items:

   1)  Develop a document explaining the rationale for assigning
       MANDATORY status to MIB variables which are optional in
       the relevant IEEE 802.3 specification (the technical
       basis for the Internet Ethernet MIB). This shall not be a
       standards-track document.

   (2) Develop an implementation report on the Ethernet MIB.
       This report shall cover MIB variables which are
       implemented in both Ethernet interface chips, and in
       software (i.e., drivers), and discuss the issues
       pertaining to both.  This report shall also summarize
       field experience with the MIB variables, especially
       concentrating on those variables which are in dispute.
       This document shall not be a standards-track document.
       While the Ethernet MIB is progressing through the
       standardization process, this document shall be
       periodically updated to reflect the latest implementation
       and operational experience.




Kastenholz                                                      [Page 1]

RFC 1369              Ethernet MIB Implementations          October 1992


   This document reflects the currently known status of 11 different
   implementations of the MIB by 7 different vendors on 7 different
   Ethernet interface chips.

2.  Observations

   There are some interesting points to be noted from this information:

   1)  Only 4 variables are actually implemented in all
       implementations: AlignmentErrors, FCSErrors,
       ExcessiveCollisions and InternalMacTransmitErrors.

   2)  There were another five variables implemented in all but
       one of the reported implementations,
       SingleCollisionFrames, MultipleCollisionFrames,
       LateCollisions, FrameTooLongs, and CarrierSenseErrors.

       Three of these variables exist in implementations that
       use the same chip as the implementation that does not
       contain the variable.  Specifically:

    A)   SingleCollisionFrames is not implemented in
         implementation number 3, which uses the AMD LANCE.
         However, other AMD LANCE implementations (7, 8, and 10)
         do implement the variable, implying that it is
         available on the LANCE.

    B)   MultipleCollisionFrames is not implemented in
         implementation number 3, which uses the AMD LANCE.
         However, other AMD LANCE implementations (7, 8, and 10)
         do implement the variable, implying that it is
         available on the LANCE.

    C)   LateCollisions is not implemented in implementation
         number 1, which uses the Intel 82586. However, another
         Intel 82586 based implementation (11) does implement
         the variable, implying that it is available on the
         Intel 82586.

    D)   CarrierSenseErrors is not implemented on implementation
         number 2, which is based on the Fujitsu 86950 chip.
         However, there is only one implementation based on this
         chip and I have not been able to locate a data sheet on
         this part so no conclusion can be drawn at this time.

    E)   FrameTooLongs is not implemented on implementation
         number 5, which is based on the National NIC 8390 chip.
         However, there is only one implementation based on this



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RFC 1369              Ethernet MIB Implementations          October 1992


         chip and I have not been able to locate a data sheet on
         this part. It should also be noted that this variable
         is easily maintained by software as a "driver-level"
         function.

   (3)  Of the 22 variables in the MIB, 11, or 1/2 of the
        variables, were implemented in about 1/2 or less of the
        implementations.

   4)   The number of variables implemented per implementation
        ranges from a low of 11 to a high of 16. The average
        number of variables truly implemented is 12.8.

   5)   The IEEE 802.3 encapsulation-specific variables
        (InRangeLengthErrors, and OutOfRangeLengthFields) are in
        2 and 0 implementations respectively.

3.  Conclusions

   From this, the author concludes that:

   The control variables (IntializeMAC, etc.) are not widely
   implemented, but this may be due to an aversion to implementing
   writable variables until security is in place.

   One vendor has stated that the reason that these variables were not
   implemented was that the vendor did not believe the variables to be
   useful, and that they were hard to implement.  Furthermore, this
   vendor has recommended dropping the variables entirely.

   The two IEEE 802.3 encapsulation variables (InRangeLengthErrors and
   OutOfRangeLengthFields) are barely implemented. In Santa Fe, the
   Working group discussed moving them to an optional, 802.3 specific,
   group. The author believes that this is justified by this
   implementation data.

   The collision histogram variables are also barely implemented.  They
   should be in their own optional group -- and they are.

   Of the remaining 13 statistical variables, 9 of them are in 10 or 11
   implementations. This is good.

   Two of them (SQETestErrors and ExcessiveDeferrals) are in 3 and 1
   implementations, respectively. This is bad.

   The remaining variables (DeferredTransmissions and
   InternalMacReceiveErrors) are in 8 or 9 implementations.




Kastenholz                                                      [Page 3]

RFC 1369              Ethernet MIB Implementations          October 1992


   It should be noted that one of the two systems that do not implement
   DeferredTransmissions is based on the AMD LANCE, and other AMD LANCE
   based systems do implement this counter, leading to the conclusion
   that DeferredTransmissions could easily be on all but one of the
   implementations.

   The other such variable, InternalMacReceiveErrors, is a general
   catchall for all other errors. If no other errors are detected by the
   hardware or software then returning 0 for the counter is perfectly
   acceptable.

   This all seems to imply either:

   1)  Splitting the statistics group into two groups, one of
       which is optional and contains SQETestErrors and
       ExcessiveDeferrals, or

   2)  Eliminating SQETestErrors and ExcessiveDeferrals) from
       the MIB.

   The variables with 8 or 9 implementations are a bit more problematic.
   They are implemented in more than 2/3s of the implementations, but it
   may not be appropriate to call this widespread implementation.
   However, it seems to be safe to conclude that the non-implementations
   of these variables is due to local implementation considerations
   rather than a fundamental lack of support for the variable.

4.  Final Action

   After consideration at the San Diego IETF Meeting on 17 March 1992,
   the Ethernet MIB Working Group made the following recommendations:

   1)  The dot3TestTdrValue object will be deprecated from the
       standard mib.  There are effectively no implementations
       of this object, and some chips were reported to return an
       incorrect value for the TDR count.

   2)  The dot3StatsInRangeLengthErrors object and the
       dot3StatsOutOfRangeLengthFields object will be deprecated
       from the MIB. These objects were not widely implemented
       and their utility in diagnosing network problems was
       strongly questioned.

   3)  The dot3InitializeMac object, the dot3MacSubLayerStatus
       object, the dot3MulticastReceiveStatus object, and the
       dot3TxEnabled object will be deprecated from the MIB.
       These objects were not widely implemented and their
       utility in diagnosing network problems was strongly



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RFC 1369              Ethernet MIB Implementations          October 1992


       questioned.

   4)  The dot3StatsExcessiveDeferrals object will be deprecated
       from the MIB.  Only one system implemented this object.
       Furthermore, its exact definition was called into question.

   5)  The dot3StatsSQETestErrors object received few
       implementations.  However, the working group strongly
       supported its retention in the MIB on the basis that
       certain forms of transceiver and cable errors that are
       not uncommon can only be detected with this counter.

   6)  The collision histogram table (dot3CollTable) will be
       kept as an optional group, even though the objects are
       not widely implemented nor is there hardware support on
       all reported chips.

5.  Implementation Data

   The following raw data has been provided by vendors, each developing
   an implementation of the Ethernet MIB.  Each reported implementation
   has a separate column in the following table. For each
   implementation/MIB Variable, a single character code has been entered
   indicating the rough implementation status of the variable.  These
   codes are:

   Y    Fully implemented, reports a truthful count, or
        indication of state. All values may be written to the
        variable with the expected action occurring.

   N    Not implemented at all. Would return a noSuchName error
        if accessed.

   C    Implemented but returns a constant value for gets and
        returns a badValue error for any set attempt to set the
        variable to a value other than this constant (writable
        variables only).














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RFC 1369              Ethernet MIB Implementations          October 1992


                         MIB           Implementation
                    Variable 1  2  3  4  5  6  7  8  9  10 11 Yesses

               InitializeMac C  C  Y  Y  Y  Y  Y  C7 C7 N  Y   6
           MacSubLayerStatus C  C  Y  Y  Y  Y  Y  C7 C7 N  C   5
      MulticastReceiveStatus C  C  Y  C3 Y  C  C  C7 C7 N  C   2
                   TxEnabled C  C  Y  Y  Y  Y  Y  C7 C7 N  C   5
                TestTdrValue C  1  C  C4 C  C  C  C4 C4 N  C   1

             AlignmentErrors Y  Y  Y  Y  Y  Y  Y  Y  Y  Y  Y  11
                   FCSErrors Y  Y  Y  Y  Y  Y  Y  Y  Y  Y  Y  11
       SingleCollisionFrames Y  Y  Y  N  Y  Y  Y  Y  Y  Y  Y  10
     MultipleCollisionFrames Y  Y  Y  N  Y  Y  Y  Y  Y  Y  Y  10
               SQETestErrors Y  C  C  C  Y  C  C  C  C  Y  C   3
       DeferredTransmissions Y  C  Y  N  Y  Y  Y  Y  Y  Y  Y   9
              LateCollisions C  Y  Y  Y  Y  Y  Y  Y  Y  Y  Y  10
         ExcessiveCollisions Y  Y  Y  Y  Y  Y  Y  Y  Y  Y  Y  11
   InternalMacTransmitErrors Y  Y  Y  Y  Y  Y  Y  Y  Y  Y  Y  11
          CarrierSenseErrors Y  C  Y  Y  Y  Y  Y  Y  Y  Y  Y  10
          ExcessiveDeferrals C  C  Y  C  C  C  C  C  C  N  C   1
               FrameTooLongs Y  Y2 Y  Y  C  Y  Y  Y  Y  Y  Y  10
         InRangeLengthErrors C  C  C  N5 C  Y  Y  C  C  N  C   2
      OutOfRangeLengthFields C  C  C  C6 C  C  C  C  C  N  C   0
    InternalMacReceiveErrors Y  Y  Y  Y  Y  C  C  Y  Y  Y  C   8

                   CollCount Y  Y  C  N  N  N  N  C  C  N  Y   3
             CollFrequencies Y  Y  C  N  N  N  N  C  C  N  Y   3
                      Yesses 13 11 16 11 15 14 14 11 11 12 13


   Notes:

   1    does not implement TDR test, but reports TDR from last
        collision!

   2    Not supported by the chip, detected solely in software.

   3    But set to disabled(2) -> badValue

   4    Underlying TDR function not implemented on this chip.

   5    Only counts frames too short though.

   6    Due to Ethernet encapsulation

   7    Implementation does not support set operations but
        reports the correct value for these.




Kastenholz                                                      [Page 6]

RFC 1369              Ethernet MIB Implementations          October 1992


   The implementations are:

            Implementation   Vendor   Chip
                         1   1        Intel 82586
                         2   1        Fujitsu 86950
                         3   2        Sonic
                         4   3        AMD Lance
                         5   4        National NIC 8390C
                         6   4        Intel 82596
                         7   4        AMD Lance
                         8   5        AMD Lance
                         9   5        AMD ILACC
                        10   6        AMD Lance
                        11   7        Intel 82586

6. Security Considerations

   Security issues are not discussed in this memo.

7. Author's Address

   Frank J. Kastenholz
   FTP Software
   2 High Street
   North Andover Mass 01845

   Phone:  508-685-4000
   EMail:  kasten@ftp.com























Kastenholz                                                      [Page 7]
