Network Working Group A. Bierman
Request for Comments: 2895 C. BUCci
Obsoletes: 2074 Cisco Systems, Inc.
Category: Standards Track R. Iddon
3Com, Inc.
August 2000

Remote Network Monitoring MIB Protocol Identifier Reference

Status of this Memo

This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.

Copyright Notice

Copyright (C) The Internet Society (2000). All Rights Reserved.

Abstract

This memo defines a notation describing protocol layers in a protocol
encapsulation, specifically for use in encoding INDEX values for the
protocolDirTable, found in the RMON-2 MIB (Remote Network Monitoring
Management Information Base) [RFC2021]. The definitions for the
standard protocol Directory base layer identifiers are also included.

The first version of the RMON Protocol Identifiers Document [RFC2074]
has been split into a standards-track Reference portion (this
document), and an Informational document. The RMON Protocol
Identifier Macros document [RFC2896] now contains the non-normative
portion of that specification.

This document obsoletes RFC2074.

Table of Contents

1 The SNMP Network Management Framework .......................... 3
2 Overview ....................................................... 3
2.1 Terms ........................................................ 4
2.2 Relationship to the Remote Network Monitoring MIB ............ 6
2.3 Relationship to the RMON Protocol Identifier Macros Document . 6
2.4 Relationship to the ATM-RMON MIB ............................. 7
2.4.1 Port Aggregation ........................................... 7
2.4.2 Encapsulation Mappings ..................................... 7
2.4.3 Counting ATM Traffic in RMON-2 Collections ................. 8
2.5 Relationship to Other MIBs ................................... 9
3 Protocol Identifier Encoding ................................... 9
3.1 ProtocolDirTable INDEX Format Examples ....................... 11
3.2 Protocol Identifier Macro Format ............................. 12
3.2.1 Lexical Conventions ........................................ 12
3.2.2 Notation for Syntax Descriptions ........................... 13
3.2.3 Grammar for the PI Language ................................ 13
3.2.4 Mapping of the Protocol Name ............................... 15
3.2.5 Mapping of the VARIANT-OF Clause ........................... 16
3.2.6 Mapping of the PARAMETERS Clause ........................... 17
3.2.6.1 Mapping of the 'countsFragments(0)' BIT .................. 18
3.2.6.2 Mapping of the 'tracksSessions(1)' BIT ................... 18
3.2.7 Mapping of the ATTRIBUTES Clause ........................... 18
3.2.8 Mapping of the DESCRIPTION Clause .......................... 19
3.2.9 Mapping of the CHILDREN Clause ............................. 19
3.2.10 Mapping of the ADDRESS-FORMAT Clause ...................... 20
3.2.11 Mapping of the DECODING Clause ............................ 20
3.2.12 Mapping of the REFERENCE Clause ........................... 20
3.3 Evaluating an Index of the ProtocolDirTable .................. 21
4 Base Layer Protocol Identifier Macros .......................... 22
4.1 Base Identifier Encoding ..................................... 22
4.1.1 Protocol Identifier Functions .............................. 22
4.1.1.1 Function 0: None ......................................... 23
4.1.1.2 Function 1: Protocol Wildcard Function ................... 23
4.2 Base Layer Protocol Identifiers .............................. 24
4.3 Encapsulation Layers ......................................... 31
4.3.1 IEEE 802.1Q ................................................ 31
5 Intellectual Property .......................................... 34
6 Acknowledgements ............................................... 35
7 References ..................................................... 35
8 IANA Considerations ............................................ 39
9 Security Considerations ........................................ 39
10 Authors' Addresses ............................................ 40
Appendix A ....................................................... 41
11 Full Copyright Statement ...................................... 42

1. The SNMP Network Management Framework

The SNMP Management Framework presently consists of five major
components:

o An overall architecture, described in RFC2571 [RFC2571].

o Mechanisms for describing and naming objects and events for the
purpose of management. The first version of this Structure of
Management Information (SMI) is called SMIv1 and described in STD
16, RFC1155 [RFC1155], STD 16, RFC1212 [RFC1212] and RFC1215
[RFC1215]. The second version, called SMIv2, is described in STD
58, RFC2578 [RFC2578], STD 58, RFC2579 [RFC2579] and STD 58, RFC
2580 [RFC2580].

o Message protocols for transferring management information. The
first version of the SNMP message protocol is called SNMPv1 and
described in STD 15, RFC1157 [RFC1157]. A second version of the
SNMP message protocol, which is not an Internet standards track
protocol, is called SNMPv2c and described in RFC1901 [RFC1901]
and RFC1906 [RFC1906]. The third version of the message protocol
is called SNMPv3 and described in RFC1906 [RFC1906], RFC2572
[RFC2572] and RFC2574 [RFC2574].

o Protocol operations for Accessing management information. The
first set of protocol operations and associated PDU formats is
described in STD 15, RFC1157 [RFC1157]. A second set of protocol
operations and associated PDU formats is described in RFC1905
[RFC1905].

o A set of fundamental applications described in RFC2573 [RFC2573]
and the view-based access control mechanism described in RFC2575
[RFC2575].

A more detailed introduction to the current SNMP Management Framework
can be found in RFC2570 [RFC2570].

Managed objects are accessed via a virtual information store, termed
the Management Information Base or MIB. Objects in the MIB are
defined using the mechanisms defined in the SMI.

This memo does not specify a MIB module.

2. Overview

The RMON-2 MIB [RFC2021] uses hierarchically formatted OCTET STRINGs
to globally identify individual protocol encapsulations in the
protocolDirTable.

This guide contains algorithms and the authoritative set of base
layer protocol identifier macros, for use within INDEX values in the
protocolDirTable.

This is the second revision of this document, and is intended to
replace the first half of the first RMON-2 Protocol Identifiers
document. [RFC2074].

2.1. Terms

The key Words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC2119 [RFC2119].

Several terms are used throughout this document, as well as in the
RMON-2 MIB [RFC2021], that should be introduced:

parent protocol:
Also called 'parent'; The encapsulating protocol identifier for
a specific protocol layer, e.g., IP is the parent protocol of
UDP. Note that base layers cannot have parent protocols. This
term may be used to refer to a specific encapsulating protocol,
or it may be used generically to refer to any encapsulating
protocol.

child protocol:
Also called 'child'; An encapsulated protocol identifier for a
specific protocol layer. e.g., UDP is a child protocol of IP.
This term may be used to refer to a specific encapsulated
protocol, or it may be used generically to refer to any
encapsulated protocol.

layer-identifier:
An octet string fragment representing a particular protocol
encapsulation layer or sub-layer. A fragment consists of
exactly four octets, encoded in network byte order. If present,
child layer-identifiers for a protocol MUST have unique values
among each other. (See section 3.3 for more details.)

protocol:
A particular protocol layer, as specified by encoding rules in
this document. Usually refers to a single layer in a given
encapsulation. Note that this term is sometimes used in the
RMON-2 MIB [RFC2021] to name a fully-specified protocol-
identifier string. In such a case, the protocol-identifier
string is named for its upper-most layer. A named protocol may
also refer to any encapsulation of that protocol.

protocol-identifier string:
An octet string representing a particular protocol
encapsulation, as specified by the encoding rules in this
document. This string is identified in the RMON-2 MIB [RFC2021]
as the protocolDirID object. A protocol-identifier string is
composed of one or more layer-identifiers read from left to
right. The left-most layer-identifier specifies a base layer
encapsulation. Each layer-identifier to the right specifies a
child layer protocol encapsulation.

protocol-identifier macro: Also called a PI macro; A macro-like
textual construct used to describe a particular networking
protocol. Only protocol attributes which are important for RMON
use are documented. Note that the term 'macro' is historical,
and PI macros are not real macros, nor are they ASN.1 macros.
The current set of published RMON PI macros can be found in the
RMON Protocol Identifier Macros document [RFC2896].

The PI macro serves several purposes:

- Names the protocol for use within the RMON-2 MIB [RFC2021].
- Describes how the protocol is encoded into an octet string.
- Describes how child protocols are identified (if applicable),
and encoded into an octet string.
- Describes which protocolDirParameters are allowed for the
protocol.
- Describes how the associated protocolDirType object is encoded
for the protocol.
- Provides reference(s) to authoritative documentation for the
protocol.

protocol-variant-identifier macro:
Also called a PI-variant macro; A special kind of PI macro, used
to describe a particular protocol layer, which cannot be
identified with a deterministic, and (usually) hierarchical
structure, like most networking protocols.

Note that the PI-variant macro and the PI-macro are defined with
a single set of syntax rules (see section 3.2), except that
different sub-clauses are required for each type.

A protocol identified with a PI-variant macro is actually a
variant of a well known encapsulation that may be present in the
protocolDirTable. This is used to document the IANA assigned
protocols, which are needed to identify protocols which cannot
be practically identified by examination of 'appropriate network
traffic' (e.g. the packets which carry them). All other
protocols (which can be identified by examination of appropriate

network traffic) SHOULD be documented using the protocol-
identifier macro. (See section 3.2 for details.)

protocol-parameter:
A single octet, corresponding to a specific layer-identifier in
the protocol-identifier. This octet is a bit-mask indicating
special functions or capabilities that this agent is providing
for the corresponding protocol. (See section 3.2.6 for
details.)

protocol-parameters string:
An octet string, which contains one protocol-parameter for each
layer-identifier in the protocol-identifier. This string is
identified in the RMON-2 MIB [RFC2021] as the
protocolDirParameters object. (See the section 3.2.6 for
details.)

protocolDirTable INDEX:
A protocol-identifier and protocol-parameters octet string pair
that have been converted to an INDEX value, according to the
encoding rules in section 7.7 of RFC1902 [RFC1902].

pseudo-protocol:
A convention or algorithm used only within this document for the
purpose of encoding protocol-identifier strings.

protocol encapsulation tree:
Protocol encapsulations can be organized into an inverted tree.
The nodes of the root are the base encapsulations. The children
nodes, if any, of a node in the tree are the encapsulations of
child protocols.

2.2. Relationship to the Remote Network Monitoring MIB

This document is intended to identify the encoding rules for the
OCTET STRING objects protocolDirID and protocolDirParameters. RMON-2
tables, such as those in the new Protocol Distribution, Host, and
Matrix groups, use a local INTEGER INDEX (protocolDirLocalIndex)
rather than complete protocolDirTable INDEX strings, to identify
protocols for counting purposes. Only the protocolDirTable uses the
protocolDirID and protocolDirParameters strings described in this
document.

This document is intentionally separated from the RMON-2 MIB objects
[RFC2021] to allow updates to this document without any republication
of MIB objects.

This document does not discuss auto-discovery and auto-population of
the protocolDirTable. This functionality is not eXPlicitly defined by
the RMON standard. An agent SHOULD populate the directory with the
'interesting' protocols on which the intended applications depend.

2.3. Relationship to the RMON Protocol Identifier Macros Document

The original RMON Protocol Identifiers document [RFC2074] contains
the protocol directory reference material, as well as many examples
of protocol identifier macros.

These macros have been moved to a separate document called the RMON
Protocol Identifier Macros document [RFC2896]. This will allow the
normative text (this document) to advance on the standards track with
the RMON-2 MIB [RFC2021], while the collection of PI macros is
maintained in an Informational RFC.

The PI Macros document is intentionally separated from this document
to allow updates to the list of published PI macros without any
republication of MIB objects or encoding rules. Protocol Identifier
macros submitted from the RMON working group and community at large
(to the RMONMIB WG mailing list at 'rmonmib@ietf.org') will be
collected, screened by the RMONMIB working group, and (if approved)
added to a subsequent version of the PI Macros document.

Macros submissions will be collected in the IANA's MIB files under
the directory "FTP://ftp.isi.edu/mib/rmonmib/rmon2_pi_macros/" and in
the RMONMIB working group mailing list message archive file
www.ietf.org/mail-archive/working-
groups/rmonmib/current/maillist.htm.

2.4. Relationship to the ATM-RMON MIB

The ATM Forum has standardized "Remote Monitoring MIB Extensions for
ATM Networks" (ATM-RMON MIB) [AF-NM-TEST-0080.000], which provides
RMON-like stats, host, matrix, and matrixTopN capability for NSAP
address-based (ATM Adaption Layer 5, AAL-5) cell traffic.

2.4.1. Port Aggregation

It it possible to correlate ATM-RMON MIB data with packet-based
RMON-2 [RFC2021] collections, but only if the ATM-RMON
'portSelGrpTable' and 'portSelTable' are configured to provide the
same level of port aggregation as used in the packet-based
collection. This will require an ATM-RMON 'portSelectGroup' to
contain a single port, in the case of traditional RMON dataSources.

2.4.2. Encapsulation Mappings

The RMON PI document does not contain explicit PI macro support for
"Multiprotocol Encapsulation over ATM Adaptation Layer 5" [RFC1483],
or ATM Forum "LAN Emulation over ATM" (LANE) [AF-LANE-0021.000].
Instead, a probe must 'fit' the ATM encapsulation to one of the base
layers defined in this document (i.e., llc, snap, or vsnap),
regardless of how the raw data is oBTained by the agent (e.g., VC-
muxing vs. LLC-muxing, or routed vs. bridged formats). See section
3.2 for details on identifying and decoding a particular base layer.

An NMS can determine some of the omitted encapsulation details by
examining the interface type (ifType) of the dataSource for a
particular RMON collection:

RFC1483 dataSource ifTypes:
- aal5(49)

LANE dataSource ifTypes:
- aflane8023(59)
- aflane8025(60)

These dataSources require implementation of the ifStackTable from the
Interfaces MIB [RFC2233]. It is possible that some implementations
will use dataSource values which indicate an ifType of 'atm(37)'
(because the ifStackTable is not supported), however this is strongly
discouraged by the RMONMIB WG.

2.4.3. Counting ATM Traffic in RMON-2 Collections

The RMON-2 Application Layer (AL) and Network Layer (NL)
(host/matrix/topN) tables require that octet counters be incremented
by the size of the particular frame, not by the size of the frame
attributed to a given protocol.

Probe implementations must use the AAL-5 frame size (not the AAL-5
payload size or encapsulated MAC frame size) as the 'frame size' for
the purpose of incrementing RMON-2 octet counters (e.g.,
'nlHostInOctets', 'alHostOutOctets').

The RMONMIB WG has not addressed issues relating to packet capture of
AAL-5 based traffic. Therefore, it is an implementation-specific
matter whether padding octets (i.e., RFC1483 VC-muxed, bridged 802.3
or 802.5 traffic, or LANE traffic) are represented in the RMON-1
'captureBufferPacketData' MIB object. Normally, the first octet of
the captured frame is the first octet of the destination MAC address
(DA).

2.5. Relationship to Other MIBs

The RMON Protocol Identifiers Reference document is intended for use
with the protocolDirTable within the RMON MIB. It is not relevant to
any other MIB, or intended for use with any other MIB.

3. Protocol Identifier Encoding

The protocolDirTable is indexed by two OCTET STRINGs, protocolDirID
and protocolDirParameters. To encode the table index, each variable-
length string is converted to an OBJECT IDENTIFIER fragment,
according to the encoding rules in section 7.7 of RFC1902 [RFC1902].
Then the index fragments are simply concatenated. (Refer to figures
1a - 1d below for more detail.)

The first OCTET STRING (protocolDirID) is composed of one or more 4-
octet "layer-identifiers". The entire string uniquely identifies a
particular node in the protocol encapsulation tree. The second OCTET
STRING, (protocolDirParameters) which contains a corresponding number
of 1-octet protocol-specific parameters, one for each 4-octet layer-
identifier in the first string.

A protocol layer is normally identified by a single 32-bit value.
Each layer-identifier is encoded in the ProtocolDirID OCTET STRING
INDEX as four sub-components [ a.b.c.d ], where 'a' - 'd' represent
each byte of the 32-bit value in network byte order. If a particular
protocol layer cannot be encoded into 32 bits, then it must be
defined as an 'ianaAssigned' protocol (see below for details on IANA
assigned protocols).

The following figures show the differences between the OBJECT
IDENTIFIER and OCTET STRING encoding of the protocol identifier
string.

Fig. 1a
protocolDirTable INDEX Format
-----------------------------

+---+--------------------------+---+---------------+
c ! c ! protocolDir
n ! protocolDirID n ! Parameters
t ! t !
+---+--------------------------+---+---------------+

Fig. 1b
protocolDirTable OCTET STRING Format
------------------------------------

protocolDirID
+----------------------------------------+

4 * N octets

+----------------------------------------+

protocolDirParameters
+----------+

N octets

+----------+

N is the number of protocol-layer-identifiers required
for the entire encapsulation of the named protocol. Note
that the layer following the base layer usually identifies
a network layer protocol, but this is not always the case,
(most notably for children of the 'vsnap' base-layer).

Fig. 1c
protocolDirTable INDEX Format Example
-------------------------------------

protocolDirID protocolDirParameters
+---+--------+--------+--------+--------+---+---+---+---+---+
c proto proto proto proto c parparparpar
n base L(B+1) L(B+2) L(B+3) n ba- L3 L4 L5
t (+flags) L3 L4 L5 t se
+---+--------+--------+--------+--------+---+---+---+---+---+ subOID
1 4 4 4 4 1 1 1 1 1 count

When encoded in a protocolDirTable INDEX, each of the two
strings must be preceded by a length sub-component. In this
example, N equals '4', the first 'cnt' field would contain
the value '16', and the second 'cnt' field would contain
the value '4'.

Fig. 1d
protocolDirTable OCTET STRING Format Example
--------------------------------------------

protocolDirID
+--------+--------+--------+--------+
proto proto proto proto
base L3 L4 L5

+--------+--------+--------+--------+ octet
4 4 4 4 count

protocolDirParameters
+---+---+---+---+
parparparpar
ba- L3 L4 L5
se
+---+---+---+---+ octet
1 1 1 1 count

Although this example indicates four encapsulated protocols, in
practice, any non-zero number of layer-identifiers may be present,
theoretically limited only by OBJECT IDENTIFIER length restrictions,
as specified in section 3.5 of RFC1902 [RFC1902].

3.1. ProtocolDirTable INDEX Format Examples

The following PI identifier fragments are examples of some fully
encoded protocolDirTable INDEX values for various encapsulations.

-- HTTP; fragments counted from IP and above
ether2.ip.tcp.www-http =
16.0.0.0.1.0.0.8.0.0.0.0.6.0.0.0.80.4.0.1.0.0

-- SNMP over UDP/IP over SNAP
snap.ip.udp.snmp =
16.0.0.0.3.0.0.8.0.0.0.0.17.0.0.0.161.4.0.0.0.0

-- SNMP over IPX over SNAP
snap.ipx.snmp =
12.0.0.0.3.0.0.129.55.0.0.144.15.3.0.0.0

-- SNMP over IPX over raw8023
ianaAssigned.ipxOverRaw8023.snmp =
12.0.0.0.5.0.0.0.1.0.0.144.15.3.0.0.0

-- IPX over LLC
llc.ipx =
8.0.0.0.2.0.0.0.224.2.0.0

-- SNMP over UDP/IP over any link layer
ether2.ip.udp.snmp
16.1.0.0.1.0.0.8.0.0.0.0.17.0.0.0.161.4.0.0.0.0

-- IP over any link layer; base encoding is IP over ether2
ether2.ip
8.1.0.0.1.0.0.8.0.2.0.0

-- AppleTalk Phase 2 over ether2
ether2.atalk
8.0.0.0.1.0.0.128.155.2.0.0

-- AppleTalk Phase 2 over vsnap
vsnap.apple-oui.atalk
12.0.0.0.4.0.8.0.7.0.0.128.155.3.0.0.0

3.2. Protocol Identifier Macro Format

The following example is meant to introduce the protocol-identifier
macro. This macro-like construct is used to represent both protocols
and protocol-variants.

If the 'VariantOfPart' component of the macro is present, then the
macro represents a protocol-variant instead of a protocol. This
clause is currently used only for IANA assigned protocols, enumerated
under the 'ianaAssigned' base-layer. The VariantOfPart component
MUST be present for IANA assigned protocols.

3.2.1. Lexical Conventions

The PI language defines the following keywords:

ADDRESS-FORMAT
ATTRIBUTES
CHILDREN
DECODING
DESCRIPTION
PARAMETERS
PROTOCOL-IDENTIFIER
REFERENCE
VARIANT-OF

The PI language defines the following punctuation elements:

{ left curly brace
} right curly brace
( left parenthesis
) right parenthesis
, comma
::= two colons and an equal sign
-- two dashes

3.2.2. Notation for Syntax Descriptions

An extended form of the BNF notation is used to specify the syntax of
the PI language. The rules for this notation are shown below:

* Literal values are specified in quotes, for example "REFERENCE"

* Non-terminal items are surrounded by less than (<) and greater
than (>) characters, for example <parmList>

* Terminal items are specified without surrounding quotes or less
than and greater than characters, for example 'lcname'

* A vertical bar () is used to indicate a choice between items,
for example 'number hstr'

* Ellipsis are used to indicate that the previous item may be
repeated one or more times, for example <parm>...

* Square brackets are used to enclose optional items, for example
[ "," <parm> ]

* An equals character (=) is used to mean "defined as," for
example '<protoName> = pname'

3.2.3. Grammar for the PI Language

The following are "terminals" of the grammar and are identical to the
same lexical elements from the MIB module language, except for hstr
and pname:

<lc> = "a" "b" "c" ... "z"
<uc> = "A" "B" "C" ... "Z"
<letter> = <lc> <uc>
<digit> = "0" "1" ... "9"
<hdigit> = <digit> "a" "A" "b" "B" ... "f" "F"

<lcname> = <lc> [ <lcrest> ]
<lcrest> = ( <letter> <digit> "-" ) [ <lcrest> ]

<pname> = ( <letter> <digit> ) [ <pnrest> ]
<pnrest> = ( <letter> <digit> "-" "_" "*" ) [ <pnrest> ]

<number> = <digit> [ <number> ] -- to a max dec. value of 4g-1

<hstr> = "0x" <hrest> -- to a max dec. value of 4g-1
<hrest> = <hdigit> [ <hrest> ]

<lf> = linefeed char
<cr> = carriage return char
<eoln> = <cr><lf> <lf>

<sp> = " "
<tab> = " "
<wspace> = { <sp> <tab> <eoln> } [<wspace>]

<string> = """ [ <strest> ] """
<strest> = ( <letter> <digit> <wspace> ) [ <strest> ]

The following is the extended BNF notation for the grammar with
starting symbol <piFile>:

-- a file containing one or more Protocol Identifier (PI)
-- definitions
<piFile> = <piDefinition>...

-- a PI definition
<piDefinition> =
<protoName> "PROTOCOL-IDENTIFIER"
[ "VARIANT-OF" <protoName> ]
"PARAMETERS" "{" [ <parmList> ] "}"
"ATTRIBUTES" "{" [ <attrList> ] "}"
"DESCRIPTION" string
[ "CHILDREN" string ]
[ "ADDRESS-FORMAT" string ]
[ "DECODING" string ]
[ "REFERENCE" string ]
"::=" "{" <encapList> "}"

-- a protocol name
<protoName> = pname

-- a list of parameters
<parmList> = <parm> [ "," <parm> ]...

-- a parameter
<parm> = lcname [<wspace>] "(" [<wspace>]
<nonNegNum> [<wspace>] ")" [<wspace>]

-- list of attributes
<attrList> = <attr> [ [<wspace>] "," [<wspace>] <attr> ]...

-- an attribute
<attr> = lcname [<wspace>] "(" [<wspace>]
<nonNegNum> [<wspace>] ")"

-- a non-negative number
<nonNegNum> = number hstr

-- list of encapsulation values
<encapList> = <encapValue> [ [<wspace>] ","
[<wspace>] <encapValue> ]...

-- an encapsulation value
<encapValue> = <baseEncapValue> <normalEncapValue>

-- base encapsulation value
<baseEncapValue> = <nonNegNum>

-- normal encapsulation value
<normalEncapValue> = <protoName> <wspace> <nonNegNum>

-- comment
<two dashes> <text> <end-of-line>

3.2.4. Mapping of the Protocol Name

The "protoName" value, called the "protocol name" shall be an ASCII
string consisting of one up to 64 characters from the following:

"A" through "Z"
"a" through "z"
"0" through "9"
dash (-)
underbar (_)
asterisk (*)
plus(+)

The first character of the protocol name is limited to one of the
following:

"A" through "Z"
"a" through "z"

"0" through "9"

This value SHOULD be the name or acronym identifying the protocol.
Note that case is significant. The value selected for the protocol
name SHOULD match the "most well-known" name or acronym for the
indicated protocol. For example, the document indicated by the URL:

ftp://ftp.isi.edu/in-notes/iana/assignments/protocol-numbers

defines IP Protocol field values, so protocol-identifier macros for
children of IP SHOULD be given names consistent with the protocol
names found in this authoritative document. Likewise, children of
UDP and TCP SHOULD be given names consistent with the port number
name assignments found in:

ftp://ftp.isi.edu/in-notes/iana/assignments/port-numbers

When the "well-known name" contains characters not allowed in
protocol names, they MUST be changed to a dash character ("-") . In
the event that the first character must be changed, the protocol name
is prepended with the letter "p", so the former first letter may be
changed to a dash.

For example, z39.50 becomes z39-50 and 914c/g becomes 914c-g. The
following protocol names are legal:

ftp, ftp-data, whois++, sql*net, 3com-tsmux, ocs_cmu

Note that it is possible in actual implementation that different
encapsulations of the same protocol (which are represented by
different entries in the protocolDirTable) will be assigned the same
protocol name. The protocolDirID INDEX value defines a particular
protocol, not the protocol name string.

3.2.5. Mapping of the VARIANT-OF Clause

This clause is present for IANA assigned protocols only. It
identifies the protocol-identifier macro that most closely represents
this particular protocol, and is known as the "reference protocol".
A protocol-identifier macro MUST exist for the reference protocol.
When this clause is present in a protocol-identifier macro, the macro
is called a 'protocol-variant-identifier'.

Any clause (e.g. CHILDREN, ADDRESS-FORMAT) in the reference
protocol-identifier macro SHOULD NOT be duplicated in the protocol-
variant-identifier macro, if the 'variant' protocols' semantics are
identical for a given clause.

Since the PARAMETERS and ATTRIBUTES clauses MUST be present in a
protocol-identifier, an empty 'ParamList' and 'AttrList' (i.e.
"PARAMETERS {}") MUST be present in a protocol-variant-identifier
macro, and the 'ParamList' and 'AttrList' found in the reference
protocol-identifier macro examined instead.

Note that if an 'ianaAssigned' protocol is defined that is not a
variant of any other documented protocol, then the protocol-
identifier macro SHOULD be used instead of the protocol-variant-
identifier version of the macro.

3.2.6. Mapping of the PARAMETERS Clause

The protocolDirParameters object provides an NMS the ability to turn
on and off expensive probe resources. An agent may support a given
parameter all the time, not at all, or subject to current resource
load.

The PARAMETERS clause is a list of bit definitions which can be
directly encoded into the associated ProtocolDirParameters octet in
network byte order. Zero or more bit definitions may be present. Only
bits 0-7 are valid encoding values. This clause defines the entire
BIT set allowed for a given protocol. A conforming agent may choose
to implement a subset of zero or more of these PARAMETERS.

By convention, the following common bit definitions are used by
different protocols. These bit positions MUST NOT be used for other
parameters. They MUST be reserved if not used by a given protocol.

Bits are encoded in a single octet. Bit 0 is the high order (left-
most) bit in the octet, and bit 7 is the low order (right-most) bit
in the first octet. Reserved bits and unspecified bits in the octet
are set to zero.

Table 3.1 Reserved PARAMETERS Bits
------------------------------------

Bit Name Description
---------------------------------------------------------------------
0 countsFragments higher-layer protocols encapsulated within
this protocol will be counted correctly even
if this protocol fragments the upper layers
into multiple packets.
1 tracksSessions correctly attributes all packets of a protocol
which starts sessions on well known ports or
sockets and then transfers them to dynamically
assigned ports or sockets thereafter (e.g. TFTP).

The PARAMETERS clause MUST be present in all protocol-identifier
macro declarations, but may be equal to zero (empty).

3.2.6.1. Mapping of the 'countsFragments(0)' BIT

This bit indicates whether the probe is correctly attributing all
fragmented packets of the specified protocol, even if individual
frames carrying this protocol cannot be identified as such. Note
that the probe is not required to actually present any re-assembled
datagrams (for address-analysis, filtering, or any other purpose) to
the NMS.

This bit MUST only be set in a protocolDirParameters octet which
corresponds to a protocol that supports fragmentation and reassembly
in some form. Note that TCP packets are not considered 'fragmented-
streams' and so TCP is not eligible.

This bit MAY be set in more than one protocolDirParameters octet
within a protocolDirTable INDEX, in the event an agent can count
fragments at more than one protocol layer.

3.2.6.2. Mapping of the 'tracksSessions(1)' BIT

The 'tracksSessions(1)' bit indicates whether frames which are part
of remapped sessions (e.g. TFTP download sessions) are correctly
counted by the probe. For such a protocol, the probe must usually
analyze all packets received on the indicated interface, and maintain
some state information, (e.g. the remapped UDP port number for TFTP).

The semantics of the 'tracksSessions' parameter are independent of
the other protocolDirParameters definitions, so this parameter MAY be
combined with any other legal parameter configurations.

3.2.7. Mapping of the ATTRIBUTES Clause

The protocolDirType object provides an NMS with an indication of a
probe's capabilities for decoding a given protocol, or the general
attributes of the particular protocol.

The ATTRIBUTES clause is a list of bit definitions which are encoded
into the associated instance of ProtocolDirType. The BIT definitions
are specified in the SYNTAX clause of the protocolDirType MIB object.

Table 3.2 Reserved ATTRIBUTES Bits
------------------------------------

Bit Name Description
---------------------------------------------------------------------
0 hasChildren indicates that there may be children of
this protocol defined in the protocolDirTable
(by either the agent or the manager).
1 addressRecognitionCapable
indicates that this protocol can be used
to generate host and matrix table entries.

The ATTRIBUTES clause MUST be present in all protocol-identifier
macro declarations, but MAY be empty.

3.2.8. Mapping of the DESCRIPTION Clause

The DESCRIPTION clause provides a textual description of the protocol
identified by this macro. Notice that it SHOULD NOT contain details
about items covered by the CHILDREN, ADDRESS-FORMAT, DECODING and
REFERENCE clauses.

The DESCRIPTION clause MUST be present in all protocol-identifier
macro declarations.

3.2.9. Mapping of the CHILDREN Clause

The CHILDREN clause provides a description of child protocols for
protocols which support them. It has three sub-sections:

- Details on the field(s)/value(s) used to select the child protocol,
and how that selection process is performed

- Details on how the value(s) are encoded in the protocol identifier
octet string

- Details on how child protocols are named with respect to their
parent protocol label(s)

The CHILDREN clause MUST be present in all protocol-identifier macro
declarations in which the 'hasChildren(0)' BIT is set in the
ATTRIBUTES clause.

3.2.10. Mapping of the ADDRESS-FORMAT Clause

The ADDRESS-FORMAT clause provides a description of the OCTET-STRING
format(s) used when encoding addresses.

This clause MUST be present in all protocol-identifier macro
declarations in which the 'addressRecognitionCapable(1)' BIT is set
in the ATTRIBUTES clause.

3.2.11. Mapping of the DECODING Clause

The DECODING clause provides a description of the decoding procedure
for the specified protocol. It contains useful decoding hints for the
implementor, but SHOULD NOT over-replicate information in documents
cited in the REFERENCE clause. It might contain a complete
description of any decoding information required.

For 'extensible' protocols ('hasChildren(0)' BIT set) this includes
offset and type information for the field(s) used for child selection
as well as information on determining the start of the child
protocol.

For 'addressRecognitionCapable' protocols this includes offset and
type information for the field(s) used to generate addresses.

The DECODING clause is optional, and MAY be omitted if the REFERENCE
clause contains pointers to decoding information for the specified
protocol.

3.2.12. Mapping of the REFERENCE Clause

If a publicly available reference document exists for this protocol
it SHOULD be listed here. Typically this will be a URL if possible;
if not then it will be the name and address of the controlling body.

The CHILDREN, ADDRESS-FORMAT, and DECODING clauses SHOULD limit the
amount of information which may currently be obtained from an
authoritative document, such as the Assigned Numbers document
[RFC1700]. Any duplication or paraphrasing of information should be
brief and consistent with the authoritative document.

The REFERENCE clause is optional, but SHOULD be implemented if an
authoritative reference exists for the protocol (especially for
standard protocols).

3.3. Evaluating an Index of the ProtocolDirTable

The following evaluation is done after a protocolDirTable INDEX value
has been converted into two OCTET STRINGs according to the INDEX
encoding rules specified in the SMI [RFC1902].

Protocol-identifiers are evaluated left to right, starting with the
protocolDirID, which length MUST be evenly divisible by four. The
protocolDirParameters length MUST be exactly one quarter of the
protocolDirID string length.

Protocol-identifier parsing starts with the base layer identifier,
which MUST be present, and continues for one or more upper layer
identifiers, until all OCTETs of the protocolDirID have been used.
Layers MUST NOT be skipped, so identifiers such as 'SNMP over IP' or
'TCP over ether2' can not exist.

The base-layer-identifier also contains a 'special function
identifier' which may apply to the rest of the protocol identifier.

Wild-carding at the base layer within a protocol encapsulation is the
only supported special function at this time. (See section 4.1.1.2
for details.)

After the protocol-identifier string (which is the value of
protocolDirID) has been parsed, each octet of the protocol-parameters
string is evaluated, and applied to the corresponding protocol layer.

A protocol-identifier label MAY map to more than one value. For
instance, 'ip' maps to 5 distinct values, one for each supported
encapsulation. (see the 'IP' section under 'L3 Protocol Identifiers'
in the RMON Protocol Identifier Macros document [RFC2896]).

It is important to note that these macros are conceptually expanded
at implementation time, not at run time.

If all the macros are expanded completely by substituting all
possible values of each label for each child protocol, a list of all
possible protocol-identifiers is produced. So 'ip' would result in 5
distinct protocol-identifiers. Likewise each child of 'ip' would map
to at least 5 protocol-identifiers, one for each encapsulation (e.g.
ip over ether2, ip over LLC, etc.).

4. Base Layer Protocol Identifier Macros

The following PROTOCOL IDENTIFIER macros can be used to construct
protocolDirID and protocolDirParameters strings.

An identifier is encoded by constructing the base-identifier, then
adding one layer-identifier for each encapsulated protocol.

Refer to the RMON Protocol Identifier Macros document [RFC2896] for a
listing of the non-base layer PI macros published by the working
group. Note that other PI macro documents may exist, and it should be
possible for an implementor to populate the protocolDirTable without
the use of the PI Macro document [RFC2896].

4.1. Base Identifier Encoding

The first layer encapsulation is called the base identifier and it
contains optional protocol-function information and the base layer
(e.g. MAC layer) enumeration value used in this protocol identifier.

The base identifier is encoded as four octets as shown in figure 2.

Fig. 2
base-identifier format
+---+---+---+---+

f op1op2 m

+---+---+---+---+ octet
1 1 1 1 count

The first octet ('f') is the special function code, found in table
4.1. The next two octets ('op1' and 'op2') are operands for the
indicated function. If not used, an operand must be set to zero. The
last octet, 'm', is the enumerated value for a particular base layer
encapsulation, found in table 4.2. All four octets are encoded in
network-byte-order.

4.1.1. Protocol Identifier Functions

The base layer identifier contains information about any special
functions to perform during collections of this protocol, as well as
the base layer encapsulation identifier.

The first three octets of the identifier contain the function code
and two optional operands. The fourth octet contains the particular
base layer encapsulation used in this protocol (fig. 2).

Table 4.1 Assigned Protocol Identifier Functions
-------------------------------------------------

Function ID Param1 Param2
----------------------------------------------------
none 0 not used (0) not used (0)
wildcard 1 not used (0) not used (0)

4.1.1.1. Function 0: None

If the function ID field (1st octet) is equal to zero, the 'op1' and
'op2' fields (2nd and 3rd octets) must also be equal to zero. This
special value indicates that no functions are applied to the protocol
identifier encoded in the remaining octets. The identifier represents
a normal protocol encapsulation.

4.1.1.2. Function 1: Protocol Wildcard Function

The wildcard function (function-ID = 1), is used to aggregate
counters, by using a single protocol value to indicate potentially
many base layer encapsulations of a particular network layer
protocol. A protocolDirEntry of this type will match any base-layer
encapsulation of the same network layer protocol.

The 'op1' field (2nd octet) is not used and MUST be set to zero.

The 'op2' field (3rd octet) is not used and MUST be set to zero.

Each wildcard protocol identifier MUST be defined in terms of a 'base
encapsulation'. This SHOULD be as 'standard' as possible for
interoperability purposes. The lowest possible base layer value
SHOULD be chosen. So, if an encapsulation over 'ether2' is
permitted, than this should be used as the base encapsulation. If not
then an encapsulation over LLC should be used, if permitted. And so
on for each of the defined base layers.

It should be noted that an agent does not have to support the non-
wildcard protocol identifier over the same base layer. For instance
a token ring only device would not normally support IP over the
ether2 base layer. Nevertheless it should use the ether2 base layer
for defining the wildcard IP encapsulation. The agent MAY also
support counting some or all of the individual encapsulations for the
same protocols, in addition to wildcard counting. Note that the
RMON-2 MIB [RFC2021] does not require that agents maintain counters
for multiple encapsulations of the same protocol. It is an
implementation-specific matter as to how an agent determines which
protocol combinations to allow in the protocolDirTable at any given
time.

4.2. Base Layer Protocol Identifiers

The base layer is mandatory, and defines the base encapsulation of
the packet and any special functions for this identifier.

There are no suggested protocolDirParameters bits for the base layer.

The suggested value for the ProtocolDirDescr field for the base layer
is given by the corresponding "Name" field in the table 4.2 below.
However, implementations are only required to use the appropriate
integer identifier values.

For most base layer protocols, the protocolDirType field should
contain bits set for the 'hasChildren(0)' and '
addressRecognitionCapable(1)' attributes. However, the special
'ianaAssigned' base layer should have no parameter or attribute bits
set.

By design, only 255 different base layer encapsulations are
supported. There are five base encapsulation values defined at this
time. Very few new base encapsulations (e.g. for new media types) are
expected to be added over time.

Table 4.2 Base Layer Encoding Values
--------------------------------------

Name ID
------------------
ether2 1
llc 2
snap 3
vsnap 4
ianaAssigned 5

-- Ether2 Encapsulation

ether2 PROTOCOL-IDENTIFIER
PARAMETERS { }
ATTRIBUTES {
hasChildren(0),
addressRecognitionCapable(1)
}
DESCRIPTION
"DIX Ethernet, also called Ethernet-II."
CHILDREN
"The Ethernet-II type field is used to select child protocols.
This is a 16-bit field. Child protocols are deemed to start at
the first octet after this type field.

Children of this protocol are encoded as [ 0.0.0.1 ], the
protocol identifier for 'ether2' followed by [ 0.0.a.b ] where
'a' and 'b' are the network byte order encodings of the high
order byte and low order byte of the Ethernet-II type value.

For example, a protocolDirID-fragment value of:
0.0.0.1.0.0.8.0 defines IP encapsulated in ether2.

Children of ether2 are named as 'ether2' followed by the type
field value in hexadecimal. The above example would be declared
as:
ether2 0x0800"
ADDRESS-FORMAT
"Ethernet addresses are 6 octets in network order."
DECODING
"Only type values greater than 1500 decimal indicate Ethernet-II
frames; lower values indicate 802.3 encapsulation (see below)."
REFERENCE
"The authoritative list of Ether Type values is identified by the
URL:

ftp://ftp.isi.edu/in-notes/iana/assignments/ethernet-numbers"
::= { 1 }

-- LLC Encapsulation

llc PROTOCOL-IDENTIFIER
PARAMETERS { }
ATTRIBUTES {
hasChildren(0),
addressRecognitionCapable(1)
}
DESCRIPTION
"The Logical Link Control (LLC) 802.2 protocol."
CHILDREN
"The LLC Source Service Access Point (SSAP) and Destination
Service Access Point (DSAP) are used to select child protocols.
Each of these is one octet long, although the least significant
bit is a control bit and should be masked out in most situations.
Typically SSAP and DSAP (once masked) are the same for a given
protocol - each end implicitly knows whether it is the server or
client in a client/server protocol. This is only a convention,
however, and it is possible for them to be different. The SSAP
is matched against child protocols first. If none is found then
the DSAP is matched instead. The child protocol is deemed to
start at the first octet after the LLC control field(s).

Children of 'llc' are encoded as [ 0.0.0.2 ], the protocol
identifier component for LLC followed by [ 0.0.0.a ] where 'a' is
the SAP value which maps to the child protocol. For example, a
protocolDirID-fragment value of:
0.0.0.2.0.0.0.240

defines NetBios over LLC.

Children are named as 'llc' followed by the SAP value in
hexadecimal. So the above example would have been named:
llc 0xf0"
ADDRESS-FORMAT
"The address consists of 6 octets of MAC address in network
order. Source routing bits should be stripped out of the address
if present."
DECODING
"Notice that LLC has a variable length protocol header; there are
always three octets (DSAP, SSAP, control). Depending on the
value of the control bits in the DSAP, SSAP and control fields
there may be an additional octet of control information.

LLC can be present on several different media. For 802.3 and
802.5 its presence is mandated (but see ether2 and raw 802.3
encapsulations). For 802.5 there is no other link layer
protocol.

Notice also that the raw802.3 link layer protocol may take
precedence over this one in a protocol specific manner such that
it may not be possible to utilize all LSAP values if raw802.3 is
also present."
REFERENCE
"The authoritative list of LLC LSAP values is controlled by the
IEEE Registration Authority:
IEEE Registration Authority
c/o Iris Ringel
IEEE Standards Dept
445 Hoes Lane, P.O. Box 1331
Piscataway, NJ 08855-1331
Phone +1 908 562 3813
Fax: +1 908 562 1571"
::= { 2 }

-- SNAP over LLC (Organizationally Unique Identifier, OUI=000)
-- Encapsulation

snap PROTOCOL-IDENTIFIER
PARAMETERS { }
ATTRIBUTES {

hasChildren(0),
addressRecognitionCapable(1)
}
DESCRIPTION
"The Sub-Network Access Protocol (SNAP) is layered on top of LLC
protocol, allowing Ethernet-II protocols to be run over a media
restricted to LLC."
CHILDREN
"Children of 'snap' are identified by Ethernet-II type values;
the SNAP Protocol Identifier field (PID) is used to select the
appropriate child. The entire SNAP protocol header is consumed;
the child protocol is assumed to start at the next octet after
the PID.

Children of 'snap' are encoded as [ 0.0.0.3 ], the protocol
identifier for 'snap', followed by [ 0.0.a.b ] where 'a' and 'b'
are the high order byte and low order byte of the Ethernet-II
type value.

For example, a protocolDirID-fragment value of:
0.0.0.3.0.0.8.0

defines the IP/SNAP protocol.

Children of this protocol are named 'snap' followed by the
Ethernet-II type value in hexadecimal. The above example would
be named:

snap 0x0800"
ADDRESS-FORMAT
"The address format for SNAP is the same as that for LLC"
DECODING
"SNAP is only present over LLC. Both SSAP and DSAP will be 0xAA
and a single control octet will be present. There are then three
octets of Organizationally Unique Identifier (OUI) and two octets
of PID. For this encapsulation the OUI must be 0x000000 (see
'vsnap' below for non-zero OUIs)."
REFERENCE
"SNAP Identifier values are assigned by the IEEE Standards
Office. The address is:
IEEE Registration Authority
c/o Iris Ringel
IEEE Standards Dept
445 Hoes Lane, P.O. Box 1331
Piscataway, NJ 08855-1331
Phone +1 908 562 3813
Fax: +1 908 562 1571"
::= { 3 }

-- Vendor SNAP over LLC (OUI != 000) Encapsulation

vsnap PROTOCOL-IDENTIFIER
PARAMETERS { }
ATTRIBUTES {
hasChildren(0),
addressRecognitionCapable(1)
}
DESCRIPTION
"This pseudo-protocol handles all SNAP packets which do not have
a zero OUI. See 'snap' above for details of those that have a
zero OUI value."
CHILDREN
"Children of 'vsnap' are selected by the 3 octet OUI; the PID is
not parsed; child protocols are deemed to start with the first
octet of the SNAP PID field, and continue to the end of the
packet. Children of 'vsnap' are encoded as [ 0.0.0.4 ], the
protocol identifier for 'vsnap', followed by [ 0.a.b.c ] where
'a', 'b' and 'c' are the 3 octets of the OUI field in network
byte order.

For example, a protocolDirID-fragment value of:
0.0.0.4.0.8.0.7 defines the Apple-specific set of protocols
over vsnap.

Children are named as 'vsnap <OUI>', where the '<OUI>' field is
represented as 3 octets in hexadecimal notation.

So the above example would be named:
'vsnap 0x080007'"
ADDRESS-FORMAT
"The LLC address format is inherited by 'vsnap'. See the 'llc'
protocol identifier for more details."
DECODING
"Same as for 'snap' except the OUI is non-zero and the SNAP
Protocol Identifier is not parsed."
REFERENCE
"SNAP Identifier values are assigned by the IEEE Standards
Office. The address is:
IEEE Registration Authority
c/o Iris Ringel
IEEE Standards Dept
445 Hoes Lane, P.O. Box 1331
Piscataway, NJ 08855-1331
Phone +1 908 562 3813
Fax: +1 908 562 1571"
::= { 4 }

-- IANA Assigned Protocols

ianaAssigned PROTOCOL-IDENTIFIER
PARAMETERS { }
ATTRIBUTES { }
DESCRIPTION
"This branch contains protocols which do not conform easily to
the hierarchical format utilized in the other link layer
branches. Usually, such a protocol 'almost' conforms to a
particular 'well-known' identifier format, but additional
criteria are used (e.g. configuration-based), making protocol
identification difficult or impossible by examination of
appropriate network traffic (preventing the any 'well-known'
protocol-identifier macro from being used).

Sometimes well-known protocols are simply remapped to a different
port number by one or more venders (e.g. SNMP). These protocols
can be identified with the 'limited extensibility' feature of the
protocolDirTable, and do not need special IANA assignments.

A centrally located list of these enumerated protocols must be
maintained by IANA to insure interoperability. (See section 2.3
for details on the document update procedure.) Support for new
link-layers will be added explicitly, and only protocols which
cannot possibly be represented in a better way will be considered
as 'ianaAssigned' protocols.

IANA protocols are identified by the base-layer-selector value [
0.0.0.5 ], followed by the four octets [ 0.0.a.b ] of the integer
value corresponding to the particular IANA protocol.

Do not create children of this protocol unless you are sure that
they cannot be handled by the more conventional link layers
above."
CHILDREN
"Children of this protocol are identified by implementation-
specific means, described (as best as possible) in the 'DECODING'
clause within the protocol-variant-identifier macro for each
enumerated protocol.

Children of this protocol are encoded as [ 0.0.0.5 ], the
protocol identifier for 'ianaAssigned', followed by [ 0.0.a.b ]
where 'a', 'b' are the network byte order encodings of the high
order byte and low order byte of the enumeration value for the
particular IANA assigned protocol.

For example, a protocolDirID-fragment value of:
0.0.0.5.0.0.0.1

defines the IPX protocol encapsulated directly in 802.3

Children are named 'ianaAssigned' followed by the numeric value
of the particular IANA assigned protocol. The above example
would be named:

'ianaAssigned 1' "
DECODING
"The 'ianaAssigned' base layer is a pseudo-protocol and is not
decoded."
REFERENCE
"Refer to individual PROTOCOL-IDENTIFIER macros for information
on each child of the IANA assigned protocol."
::= { 5 }

-- The following protocol-variant-identifier macro declarations are
-- used to identify the RMONMIB IANA assigned protocols in a
-- proprietary way, by simple enumeration.

ipxOverRaw8023 PROTOCOL-IDENTIFIER
VARIANT-OF ipx
PARAMETERS { }
ATTRIBUTES { }
DESCRIPTION
"This pseudo-protocol describes an encapsulation of IPX over
802.3, without a type field.

Refer to the macro for IPX for additional information about this
protocol."
DECODING
"Whenever the 802.3 header indicates LLC a set of protocol
specific tests needs to be applied to determine whether this is a
'raw8023' packet or a true 802.2 packet. The nature of these
tests depends on the active child protocols for 'raw8023' and is
beyond the scope of this document."
::= {
ianaAssigned 1, -- [0.0.0.1]
802-1Q 0x05000001 -- 1Q_IANA [5.0.0.1]
}

4.3. Encapsulation Layers

Encapsulation layers are positioned between the base layer and the
network layer. It is an implementation-specific matter whether a
probe exposes all such encapsulations in its RMON-2 Protocol
Directory.

4.3.1. IEEE 802.1Q

RMON probes may encounter 'VLAN tagged' frames on monitored links.
The IEEE Virtual LAN (VLAN) encapsulation standards [IEEE802.1Q] and
[IEEE802.1D-1998], define an encapsulation layer inserted after the
MAC layer and before the network layer. This section defines a PI
macro which supports most (but not all) features of that
encapsulation layer.

Most notably, the RMON PI macro '802-1Q' does not expose the Token
Ring Encapsulation (TR-encaps) bit in the TCI portion of the VLAN
header. It is an implementation specific matter whether an RMON
probe converts LLC-Token Ring (LLC-TR) formatted frames to LLC-Native
(LLC-N) format, for the purpose of RMON collection.

In order to support the Ethernet and LLC-N formats in the most
efficient manner, and still maintain alignment with the RMON-2 '
collapsed' base layer approach (i.e., support for snap and vsnap),
the children of 802dot1Q are encoded a little differently than the
children of other base layer identifiers.

802-1Q PROTOCOL-IDENTIFIER
PARAMETERS { }
ATTRIBUTES {
hasChildren(0)
}
DESCRIPTION
"IEEE 802.1Q VLAN Encapsulation header.

Note that the specific encoding of the TPID field is not
explicitly identified by this PI macro. Ethernet-encoded vs.
SNAP-encoded TPID fields can be identified by the ifType of the
data source for a particular RMON collection, since the SNAP-
encoded format is used exclusively on Token Ring and FDDI media.
Also, no information held in the TCI field (including the TR-
encap bit) is identified in protocolDirID strings utilizing this
PI macro."

CHILDREN
"The first byte of the 4-byte child identifier is used to
distinguish the particular base encoding that follows the 802.1Q
header. The remaining three bytes are used exactly as defined by
the indicated base layer encoding.

In order to simplify the child encoding for the most common
cases, the 'ether2' and 'snap' base layers are combined into a
single identifier, with a value of zero. The other base layers
are encoded with values taken from Table 4.2.

802-1Q Base ID Values
---------------------

Base Table 4.2 Base-ID
Layer Encoding Encoding
-------------------------------------
ether2 1 0
llc 2 2
snap 3 0
vsnap 4 4
ianaAssigned 5 5

The generic child layer-identifier format is shown below:

802-1Q Child Layer-Identifier Format
+--------+--------+--------+--------+
Base
ID base-specific format

+--------+--------+--------+--------+
1 3 octet count

Base ID == 0
------------
For payloads encoded with either the Ethernet or LLC/SNAP headers
following the VLAN header, children of this protocol are
identified exactly as described for the 'ether2' or 'snap' base
layers.

Children are encoded as [ 0.0.129.0 ], the protocol identifier
for '802-1Q' followed by [ 0.0.a.b ] where 'a' and 'b' are the
network byte order encodings of the high order byte and low order
byte of the Ethernet-II type value.

For example, a protocolDirID-fragment value of:
0.0.0.1.0.0.129.0.0.0.8.0
defines IP, VLAN-encapsulated in ether2.

Children of this format are named as '802-1Q' followed by the
type field value in hexadecimal.

So the above example would be declared as:
'802-1Q 0x0800'.

Base ID == 2
------------
For payloads encoded with a (non-SNAP) LLC header following the
VLAN header, children of this protocol are identified exactly as
described for the 'llc' base layer.

Children are encoded as [ 0.0.129.0 ], the protocol identifier
component for 802.1Q, followed by [ 2.0.0.a ] where 'a' is the
SAP value which maps to the child protocol. For example, a
protocolDirID-fragment value of:
0.0.0.1.0.0.129.0.2.0.0.240

defines NetBios, VLAN-encapsulated over LLC.

Children are named as '802-1Q' followed by the SAP value in
hexadecimal, with the leading octet set to the value 2.

So the above example would have been named:
'802-1Q 0x020000f0'

Base ID == 4
------------
For payloads encoded with LLC/SNAP (non-zero OUI) headers
following the VLAN header, children of this protocol are
identified exactly as described for the 'vsnap' base layer.

Children are encoded as [ 0.0.129.0 ], the protocol identifier
for '802-1Q', followed by [ 4.a.b.c ] where 'a', 'b' and 'c' are
the 3 octets of the OUI field in network byte order.

For example, a protocolDirID-fragment value of:
0.0.0.1.0.0.129.0.4.8.0.7 defines the Apple-specific set of
protocols, VLAN-encapsulated over vsnap.

Children are named as '802-1Q' followed by the <OUI> value, which
is represented as 3 octets in hexadecimal notation, with a
leading octet set to the value 4.

So the above example would be named:
'802-1Q 0x04080007'.

Base ID == 5
------------
For payloads which can only be identified as 'ianaAssigned'
protocols, children of this protocol are identified exactly as
described for the 'ianaAssigned' base layer.

Children are encoded as [ 0.0.129.0 ], the protocol identifier
for '802-1Q', followed by [ 5.0.a.b ] where 'a' and 'b' are the
network byte order encodings of the high order byte and low order
byte of the enumeration value for the particular IANA assigned
protocol.

For example, a protocolDirID-fragment value of:
0.0.0.1.0.0.129.0.5.0.0.0.1

defines the IPX protocol, VLAN-encapsulated directly in 802.3

Children are named '802-1Q' followed by the numeric value of the
particular IANA assigned protocol, with a leading octet set to
the value of 5.

Children are named '802-1Q' followed by the hexadecimal encoding
of the child identifier. The above example would be named:

'802-1Q 0x05000001'. "
DECODING
"VLAN headers and tagged frame structure are defined in
[IEEE802.1Q]."
REFERENCE
"The 802.1Q Protocol is defined in the Draft Standard for Virtual
Bridged Local Area Networks [IEEE802.1Q]."
::= {
ether2 0x8100 -- Ethernet or SNAP encoding of TPID
-- snap 0x8100 ** excluded to reduce PD size & complexity
}

5. Intellectual Property

The IETF takes no position regarding the validity or scope of any
intellectual property or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; neither does it represent that it
has made any effort to identify any such rights. Information on the
IETF's procedures with respect to rights in standards-track and
standards-related documentation can be found in BCP-11. Copies of
claims of rights made available for publication and any assurances of
licenses to be made available, or the result of an attempt made to

obtain a general license or permission for the use of such
proprietary rights by implementors or users of this specification can
be obtained from the IETF Secretariat."

The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights which may cover technology that may be required to practice
this standard. Please address the information to the IETF Executive
Director.

6. Acknowledgements

This document was produced by the IETF RMONMIB Working Group.

The authors wish to thank the following people for their
contributions to this document:

Anil Singhal
Frontier Software Development, Inc.

Jeanne Haney
Bay Networks

Dan Hansen
Network General Corp.

Special thanks are in order to the following people for writing RMON
PI macro compilers, and improving the specification of the PI macro
language:

David Perkins
DeskTalk Systems, Inc.

Skip Koppenhaver
Technically Elite, Inc.

7. References

[AF-LANE-0021.000] LAN Emulation Sub-working Group, B. Ellington,
"LAN Emulation over ATM - Version 1.0", AF-
LANE-0021.000, ATM Forum, IBM, January 1995.

[AF-NM-TEST-0080.000] Network Management Sub-working Group, Test
Sub-working Group, A. Bierman, "Remote
Monitoring MIB Extensions for ATM Networks",
AF- NM-TEST-0080.000, ATM Forum, Cisco Systems,
February 1997.

[IEEE802.1D-1998] LAN MAN Standards Committee of the IEEE
Computer Society, "Information technology --
Telecommunications and information exchange
between systems -- Local and metropolitan area
networks -- Common specification -- Part 3:
Media Access Control (MAC) Bridges", ISO/IEC
Final DIS 15802-3 (IEEE P802.1D/D17) Institute
of Electrical and Electronics Engineers, Inc.,
May 1998.

[IEEE802.1Q] LAN MAN Standards Committee of the IEEE
Computer Society, "IEEE Standards for Local and
Metropolitan Area Networks: Virtual Bridged
Local Area Networks", Draft Standard
P802.1Q/D11, Institute of Electrical and
Electronics Engineers, Inc., July 1998.

[RFC1155] Rose, M. and K. McCloghrie, "Structure and
Identification of Management Information for
TCP/IP-based Internets", STD 16, RFC1155, May
1990.

[RFC1157] Case, J., Fedor, M., Schoffstall, M. and J.
Davin, "Simple Network Management Protocol",
STD 15, RFC1157, May 1990.

[RFC1212] Rose, M. and K. McCloghrie, "Concise MIB
Definitions", STD 16, RFC1212, March 1991.

[RFC1215] Rose, M., "A Convention for Defining Traps for
use with the SNMP", RFC1215, March 1991.

[RFC1483] Heinanen, J., "Multiprotocol Encapsulation over
ATM Adaptation Layer 5", RFC1483, July 1993.

[RFC1700] Reynolds, J. and J. Postel, "Assigned Numbers",
STD 2, RFC1700, October 1994.

[RFC1901] Case, J., McCloghrie, K., Rose, M. and S.
Waldbusser, "Introduction to Community-based
SNMPv2", RFC1901, January 1996.

[RFC1902] Case, J., McCloghrie, K., Rose, M. and S.
Waldbusser, "Structure of Management
Information for version 2 of the Simple Network
Management Protocol (SNMPv2)", RFC1902,
January 1996.

[RFC1903] Case, J., McCloghrie, K., Rose, M. and S.
Waldbusser, "Textual Conventions for version 2
of the Simple Network Management Protocol
(SNMPv2)", RFC1903, January 1996.

[RFC1904] Case, J., McCloghrie, K., Rose, M. and S.
Waldbusser, "Conformance Statements for version
2 of the Simple Network Management Protocol
(SNMPv2)", RFC1904, January 1996.

[RFC1905] Case, J., McCloghrie, K., Rose, M. and S.
Waldbusser, "Protocol Operations for Version 2
of the Simple Network Management Protocol
(SNMPv2)", RFC1905, January 1996.

[RFC1906] Case, J., McCloghrie, K., Rose, M. and S.
Waldbusser, "Transport Mappings for Version 2
of the Simple Network Management Protocol
(SNMPv2)"", RFC1906, January 1996.

[RFC2021] Waldbusser, S., "Remote Network Monitoring MIB
(RMON-2)", RFC2021, January 1997.

[RFC2074] Bierman, A. and R. Iddon, "Remote Network
Monitoring MIB Protocol Identifiers", RFC2074,
January 1997.

[RFC2119] Bradner, S., "Key words for use in RFCs to
Indicate Requirement Levels", BCP 14, RFC2119,
March 1997.

[RFC2233] McCloghrie, K. and F. Kastenholz, "The
Interfaces Group MIB Using SMIv2", RFC2233,
November 1997.

[RFC2271] Harrington, D., Presuhn, R. and B. Wijnen, "An
Architecture for Describing SNMP Management
Frameworks", RFC2271, January 1998.

[RFC2272] Case, J., Harrington D., Presuhn R. and B.
Wijnen, "Message Processing and Dispatching for
the Simple Network Management Protocol (SNMP)",
RFC2272, January 1998.

[RFC2273] Levi, D., Meyer, P. and B. Stewart, "SNMPv3
Applications", RFC2273, January 1998.

[RFC2274] Blumenthal, U. and B. Wijnen, "User-based
Security Model (USM) for version 3 of the
Simple Network Management Protocol (SNMPv3)",
RFC2274, January 1998.

[RFC2275] Wijnen, B., Presuhn, R. and K. McCloghrie,
"View-based Access Control Model (VACM) for the
Simple Network Management Protocol (SNMP)", RFC
2275, January 1998.

[RFC2570] Case, J., Mundy, R., Partain, D. and B.
Stewart, "Introduction to Version 3 of the
Internet-standard Network Management
Framework", RFC2570, April 1999.

[RFC2571] Harrington, D., Presuhn, R. and B. Wijnen, "An
Architecture for Describing SNMP Management
Frameworks", RFC2571, April 1999.

[RFC2572] Case, J., Harrington D., Presuhn R. and B.
Wijnen, "Message Processing and Dispatching for
the Simple Network Management Protocol (SNMP)",
RFC2572, April 1999.

[RFC2573] Levi, D., Meyer, P. and B. Stewart, "SNMPv3
Applications", RFC2573, April 1999.

[RFC2574] Blumenthal, U. and B. Wijnen, "User-based
Security Model (USM) for version 3 of the
Simple Network Management Protocol (SNMPv3)",
RFC2574, April 1999.

[RFC2575] Wijnen, B., Presuhn, R. and K. McCloghrie,
"View-based Access Control Model (VACM) for the
Simple Network Management Protocol (SNMP)", RFC
2575, April 1999.

[RFC2578] McCloghrie, K., Perkins, D., Schoenwaelder, J.,
Case, J., Rose, M. and S. Waldbusser,
"Structure of Management Information Version 2
(SMIv2)", STD 58, RFC2578, April 1999.

[RFC2579] McCloghrie, K., Perkins, D., Schoenwaelder, J.,
Case, J., Rose, M. and S. Waldbusser, "Textual
Conventions for SMIv2", STD 58, RFC2579, April
1999.

[RFC2580] McCloghrie, K., Perkins, D., Schoenwaelder, J.,
Case, J., Rose, M. and S. Waldbusser,
"Conformance Statements for SMIv2", STD 58, RFC
2580, April 1999.

[RFC2896] Bierman, A., Bucci, C. and R. Iddon, "Remote
Network Monitoring MIB Protocol Identifier
Macros", RFC2896, August 2000.

8. IANA Considerations

The protocols identified in this specification are almost entirely
defined in external documents. In some rare cases, an arbitrary
Protocol Identifier assignment must be made in order to support a
particular protocol in the RMON-2 protocolDirTable. Protocol
Identifier macros for such protocols will be defined under the '
ianaAssigned' base layer (see sections 3. and 4.2).

At this time, only one protocol is defined under the ianaAssigned
base layer, called 'ipxOverRaw8023' (see section 4.2).

9. Security Considerations

This document discusses the syntax and semantics of textual
descriptions of networking protocols, not the definition of any
networking behavior. As such, no security considerations are raised
by this memo.

10. Authors' Addresses

Andy Bierman
Cisco Systems, Inc.
170 West Tasman Drive
San Jose, CA USA 95134

Phone: +1 408-527-3711
EMail: abierman@cisco.com

Chris Bucci
Cisco Systems, Inc.
170 West Tasman Drive
San Jose, CA USA 95134

Phone: +1 408-527-5337
EMail: cbucci@cisco.com

Robin Iddon
c/o 3Com Inc.
Blackfriars House
40/50 Blackfrias Street
Edinburgh, EH1 1NE, UK

Phone: +44 131.558.3888
EMail: None

Appendix A: Changes since RFC2074

The differences between RFC2074 and this document are:

- RFC2074 has been split into a reference document
(this document) on the standards track and an informational
document [RFC2896], in order to remove most
protocol identifier macros out of the standards track document.
- Administrative updates; added an author, added copyrights,
updated SNMP framework boilerplate;
- Updated overview section.
- Section 2.1 MUST, SHOULD text added per template
- Section 2.1 added some new terms
- parent protocol
- child protocol
- protocol encapsulation tree
- Added section 2.3 about splitting into 2 documents:

"Relationship to the RMON Protocol Identifier Macros Document"
- Added section 2.4 "Relationship to the ATM-RMON MIB"
- rewrote section 3.2 "Protocol Identifier Macro Format"
But no semantic changes were made; The PI macro syntax
is now specified in greater detail using BNF notation.
- Section 3.2.3.1 "Mapping of the 'countsFragments(0)' BIT"
- this section was clarified to allow multiple
protocolDirParameters octets in a given PI string
to set the 'countsFragments' bit. The RFCversion
says just one octet can set this BIT. It is a
useful feature to identify fragmentation at
multiple layers, and most RMON-2 agents were
already doing this, so the WG agreed to this
clarification.
- Added section 4.3 "Encapsualtion Layers"
- This document ends after the base layer encapsulation
definitions (through RFC2074, section 5.2)
- Added Intellectual Property section
- Moved RFC2074 section 5.3
"L3: Children of Base Protocol Identifiers"
through the end of RFC2074, to the PI Reference [RFC2896]
document, in which many new protocol identifier macros were
added for application protocols and non-IP protocol
stacks.
- Acknowledgements section has been updated

11. Full Copyright Statement

Copyright (C) The Internet Society (2000). All Rights Reserved.

This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than
English.

The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns.

This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

Acknowledgement

Funding for the RFCEditor function is currently provided by the
Internet Society.