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rfc:rfc1369

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

Kastenholz [Page 2] 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

Kastenholz [Page 4] 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).

Kastenholz [Page 5] 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]

/data/webs/external/dokuwiki/data/pages/rfc/rfc1369.txt · Last modified: 1992/10/26 23:01 (external edit)