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Versions: 02 03 04 05 06 RFC 2667

IFMIB Working Group                                       Dave Thaler
INTERNET-DRAFT                                              Microsoft
Expires December 1999                                    15 June 1999

                             IP Tunnel MIB
                  <draft-ietf-ifmib-tunnel-mib-06.txt>

Status of this Memo

This document is an Internet-Draft and is in full conformance with all
provisions of Section 10 of RFC2026.

Internet-Drafts are working documents of the Internet Engineering Task
Force (IETF), its areas, and its working groups.  Note that other groups
may also distribute working documents as Internet-Drafts.

Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time.  It is inappropriate to use Internet-Drafts as reference material
or to cite them other than as "work in progress."

The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt

The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.

Copyright Notice

Copyright (C) The Internet Society (1999).  All Rights Reserved.

1.  Abstract

This memo defines a Management Information Base (MIB) for use with
network management protocols in the Internet community.  In particular,
it describes managed objects used for managing tunnels of any type over
IPv4 networks.  Extension MIBs may be designed for managing protocol-

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specific objects. Likewise, extension MIBs may be designed for managing
security-specific objects.  This MIB does not support tunnels over non-
IPv4 networks (including IPv6 networks).  Management of such tunnels may
be supported by other MIBs.

2.  Introduction

Over the past several years, there have been a number of "tunneling"
protocols specified by the IETF (see [28] for an early discussion of the
model and examples).  This document describes a Management Information
Base (MIB) used for managing tunnels of any type over IPv4 networks,
including GRE [16,17], IP-in-IP [18], Minimal Encapsulation [19], L2TP
[20], PPTP [21], L2F [25], UDP (e.g., [26]), ATMP [22], and IPv6-in-IPv4
[27] tunnels.

Extension MIBs may be designed for managing protocol-specific objects.
Likewise, extension MIBs may be designed for managing security-specific
objects (e.g., IPSEC [24]), and traffic conditioner [29] objects.
Finally, this MIB does not support tunnels over non-IPv4 networks
(including IPv6 networks).  Management of such tunnels may be supported
by other MIBs.

3.  The SNMP Network Management Framework

The SNMP Management Framework presently consists of five major
components:

o    An overall architecture, described in RFC 2571 [1].

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 RFC
     1155 [2], RFC 1212 [3] and RFC 1215 [4]. The second version, called
     SMIv2, is described in RFC 2578 [5], RFC 2579 [6] and RFC 2580 [7].

o    Message protocols for transferring management information. The
     first version of the SNMP message protocol is called SNMPv1 and
     described in RFC 1157 [8]. A second version of the SNMP message
     protocol, which is not an Internet standards track protocol, is
     called SNMPv2c and described in RFC 1901 [9] and RFC 1906 [10].
     The third version of the message protocol is called SNMPv3 and
     described in RFC 1906 [10], RFC 2572 [11] and RFC 2574 [12].

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o    Protocol operations for accessing management information. The first
     set of protocol operations and associated PDU formats is described
     in RFC 1157 [8]. A second set of protocol operations and associated
     PDU formats is described in RFC 1905 [13].

o    A set of fundamental applications described in RFC 2573 [14] and
     the view-based access control mechanism described in RFC 2575 [15].

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 specifies a MIB module that is compliant to the SMIv2. A MIB
conforming to the SMIv1 can be produced through the appropriate
translations. The resulting translated MIB must be semantically
equivalent, except where objects or events are omitted because no
translation is possible (use of Counter64). Some machine readable
information in SMIv2 will be converted into textual descriptions in
SMIv1 during the translation process. However, this loss of machine
readable information is not considered to change the semantics of the
MIB.

4.  Overview

This MIB module contains two tables:

o    the Tunnel Interface Table, containing information on the tunnels
     known to a router; and

o    the Tunnel Config Table, which can be used for dynamic creation of
     tunnels, and also provides a mapping from endpoint addresses to the
     current interface index value.

4.1.  Relationship to the Interfaces MIB

This section clarifies the relationship of this MIB to the Interfaces
MIB [23].  Several areas of correlation are addressed in the following
subsections.  The implementor is referred to the Interfaces MIB document
in order to understand the general intent of these areas.

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4.1.1.  Layering Model

Each logical interface (physical or virtual) has an ifEntry in the
Interfaces MIB [23].  Tunnels are handled by creating a logical
interface (ifEntry) for each tunnel. These are then correlated, using
the ifStack table of the Interfaces MIB, to those interfaces on which
the local IPv4 addresses of the tunnels are configured.  The basic
model, therefore, looks something like this (for example):

   | |         | |          | |
+--+ +---+  +--+ +---+      | |
|IP-in-IP|  |  GRE   |      | |
| tunnel |  | tunnel |      | |
+--+ +---+  +--+ +---+      | |
   | |         | |          | |    <== attachment to underlying
+--+ +---------+ +----------+ +--+     interfaces, to be provided
|       Physical interface       |     by ifStack table
+--------------------------------+

4.1.2.  ifRcvAddressTable

   The ifRcvAddressTable usage is defined in the MIBs defining the
   encapsulation below the network layer.  For example, if IP-in-IP
   encapsulation is being used, the ifRcvAddressTable is defined by IP-
   in-IP.

4.1.3.  ifEntry

   IfEntries are defined in the MIBs defining the encapsulation below
   the network layer.  For example, if IP-in-IP encapsulation [20] is
   being used, the ifEntry is defined by IP-in-IP.

   The ifType of a tunnel should be set to "tunnel" (131).  An entry in
   the IP Tunnel MIB will exist for every ifEntry with this ifType.  An
   implementation of the IP Tunnel MIB may allow ifEntries to be created
   via the tunnelConfigTable.  Creating a tunnel will also add an entry
   in the ifTable and in the tunnelIfTable, and deleting a tunnel will
   likewise delete the entry in the ifTable and the tunnelIfTable.

   The use of two different tables in this MIB was an important design
   decision.  Traditionally, ifIndex values are chosen by agents, and
   are permitted to change across restarts.  Allowing row creation
   directly in the Tunnel Interface Table, indexed by ifIndex, would

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   complicate row creation and/or cause interoperability problems (if
   each agent had special restrictions on ifIndex). Instead, a separate
   table is used which is indexed only by objects over which the manager
   has control.  Namely, these are the addresses of the tunnel endpoints
   and the encapsulation protocol.  Finally, an additional manager-
   chosen ID is used in the index to support protocols such as L2F which
   allow multiple tunnels between the same endpoints.

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5.  Definitions

TUNNEL-MIB DEFINITIONS ::= BEGIN

IMPORTS
    MODULE-IDENTITY, OBJECT-TYPE, transmission,
    Integer32, IpAddress             FROM SNMPv2-SMI
    RowStatus                        FROM SNMPv2-TC
    MODULE-COMPLIANCE, OBJECT-GROUP  FROM SNMPv2-CONF
    ifIndex, InterfaceIndexOrZero    FROM IF-MIB;

tunnelMIB MODULE-IDENTITY
    LAST-UPDATED "9906151200Z" -- June 15, 1999
    ORGANIZATION "IETF Interfaces MIB Working Group"
    CONTACT-INFO
            " Dave Thaler
              Microsoft Corporation
              One Microsoft Way
              Redmond, WA  98052-6399
              EMail: dthaler@dthaler.microsoft.com"
    DESCRIPTION
            "The MIB module for management of IP Tunnels, independent of
            the specific encapsulation scheme in use."
    REVISION     "9906151200Z" -- June 15, 1999
    DESCRIPTION
            "Initial version, published as RFC xxxx (to be filled in by
            RFC-Editor)."
    ::= { transmission 131 }

tunnelMIBObjects OBJECT IDENTIFIER ::= { tunnelMIB 1 }

tunnel      OBJECT IDENTIFIER ::= { tunnelMIBObjects 1 }

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-- the IP Tunnel MIB-Group
--
-- a collection of objects providing information about
-- IP Tunnels

tunnelIfTable OBJECT-TYPE
    SYNTAX     SEQUENCE OF TunnelIfEntry
    MAX-ACCESS not-accessible
    STATUS     current
    DESCRIPTION
            "The (conceptual) table containing information on configured
            tunnels."
    ::= { tunnel 1 }

tunnelIfEntry OBJECT-TYPE
    SYNTAX     TunnelIfEntry
    MAX-ACCESS not-accessible
    STATUS     current
    DESCRIPTION
            "An entry (conceptual row) containing the information on a
            particular configured tunnel."
    INDEX      { ifIndex }
    ::= { tunnelIfTable 1 }

TunnelIfEntry ::= SEQUENCE {
    tunnelIfLocalAddress            IpAddress,
    tunnelIfRemoteAddress           IpAddress,
    tunnelIfEncapsMethod            INTEGER,
    tunnelIfHopLimit                Integer32,
    tunnelIfSecurity                INTEGER,
    tunnelIfTOS                     Integer32
}

tunnelIfLocalAddress OBJECT-TYPE
    SYNTAX     IpAddress
    MAX-ACCESS read-only
    STATUS     current
    DESCRIPTION
            "The address of the local endpoint of the tunnel (i.e., the
            source address used in the outer IP header), or 0.0.0.0 if
            unknown."
    ::= { tunnelIfEntry 1 }

tunnelIfRemoteAddress OBJECT-TYPE

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    SYNTAX     IpAddress
    MAX-ACCESS read-only
    STATUS     current
    DESCRIPTION
            "The address of the remote endpoint of the tunnel (i.e., the
            destination address used in the outer IP header), or 0.0.0.0
            if unknown."
    ::= { tunnelIfEntry 2 }

tunnelIfEncapsMethod OBJECT-TYPE
    SYNTAX     INTEGER {
                   other(1),   -- none of the following
                   direct(2),  -- no intermediate header
                   gre(3),     -- GRE encapsulation
                   minimal(4), -- Minimal encapsulation
                   l2tp(5),    -- L2TP encapsulation
                   pptp(6),    -- PPTP encapsulation
                   l2f(7),     -- L2F encapsulation
                   udp(8),     -- UDP encapsulation
                   atmp(9)     -- ATMP encapsulation
               }
    MAX-ACCESS read-only
    STATUS     current
    DESCRIPTION
            "The encapsulation method used by the tunnel. The value
            direct indicates that the packet is encapsulated directly
            within a normal IPv4 header, with no intermediate header,
            and unicast to the remote tunnel endpoint (e.g., an RFC 2003
            IP-in-IP tunnel, or an RFC 1933 IPv6-in-IPv4 tunnel). The
            value minimal indicates that a Minimal Forwarding Header
            (RFC 2004) is inserted between the outer header and the
            payload packet. The value UDP indicates that the payload
            packet is encapsulated within a normal UDP packet (e.g., RFC
            1234).  The remaining protocol-specific values indicate that
            a header of the protocol of that name is inserted between
            the outer header and the payload header."
    ::= { tunnelIfEntry 3 }

tunnelIfHopLimit OBJECT-TYPE
    SYNTAX     Integer32 (0..255)
    MAX-ACCESS read-write
    STATUS     current
    DESCRIPTION
            "The TTL to use in the outer IP header. A value of 0
            indicates that the value is copied from the payload's

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            header."
    ::= { tunnelIfEntry 4 }

tunnelIfSecurity OBJECT-TYPE
    SYNTAX     INTEGER {
                   none(1),   -- no security
                   ipsec(2),  -- IPSEC security
                   other(3)
               }
    MAX-ACCESS read-only
    STATUS     current
    DESCRIPTION
            "The method used by the tunnel to secure the outer IP
            header.  The value ipsec indicates that IPsec is used
            between the tunnel endpoints for authentication or
            encryption or both.  More specific security-related
            information may be available in a MIB for the security
            protocol in use."
    ::= { tunnelIfEntry 5 }

tunnelIfTOS OBJECT-TYPE
    SYNTAX     Integer32 (-2..63)
    MAX-ACCESS read-write
    STATUS     current
    DESCRIPTION
            "The method used to set the high 6 bits of the TOS in the
            outer IP header.  A value of -1 indicates that the bits are
            copied from the payload's header. A value of -2 indicates
            that a traffic conditioner is invoked and more information
            may be available in a traffic conditioner MIB.  A value
            between 0 and 63 inclusive indicates that the bit field is
            set to the indicated value."
    ::= { tunnelIfEntry 6 }

tunnelConfigTable OBJECT-TYPE
    SYNTAX     SEQUENCE OF TunnelConfigEntry
    MAX-ACCESS not-accessible
    STATUS     current
    DESCRIPTION
            "The (conceptual) table containing information on configured
            tunnels.  This table can be used to map a set of tunnel
            endpoints to the associated ifIndex value.  It can also be
            used for row creation.  Note that every row in the
            tunnelIfTable with a fixed destination address should have a

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            corresponding row in the tunnelConfigTable, regardless of
            whether it was created via SNMP."
    ::= { tunnel 2 }

tunnelConfigEntry OBJECT-TYPE
    SYNTAX     TunnelConfigEntry
    MAX-ACCESS not-accessible
    STATUS     current
    DESCRIPTION
            "An entry (conceptual row) containing the information on a
            particular configured tunnel."
    INDEX      { tunnelConfigLocalAddress,
                 tunnelConfigRemoteAddress,
                 tunnelConfigEncapsMethod,
                 tunnelConfigID }
    ::= { tunnelConfigTable 1 }

TunnelConfigEntry ::= SEQUENCE {
    tunnelConfigLocalAddress            IpAddress,
    tunnelConfigRemoteAddress           IpAddress,
    tunnelConfigEncapsMethod            INTEGER,
    tunnelConfigID                      Integer32,
    tunnelConfigIfIndex                 InterfaceIndexOrZero,
    tunnelConfigStatus                  RowStatus
}

tunnelConfigLocalAddress OBJECT-TYPE
    SYNTAX     IpAddress
    MAX-ACCESS not-accessible
    STATUS     current
    DESCRIPTION
            "The address of the local endpoint of the tunnel, or 0.0.0.0
            if the device is free to choose any of its addresses at
            tunnel establishment time."
    ::= { tunnelConfigEntry 1 }

tunnelConfigRemoteAddress OBJECT-TYPE
    SYNTAX     IpAddress
    MAX-ACCESS not-accessible
    STATUS     current
    DESCRIPTION
            "The address of the remote endpoint of the tunnel."
    ::= { tunnelConfigEntry 2 }

tunnelConfigEncapsMethod OBJECT-TYPE

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    SYNTAX     INTEGER {
                   other(1),   -- none of the following
                   direct(2),  -- no intermediate header
                   gre(3),     -- GRE encapsulation
                   minimal(4), -- Minimal encapsulation
                   l2tp(5),    -- L2TP encapsulation
                   pptp(6),    -- PPTP encapsulation
                   l2f(7),     -- L2F encapsulation
                   udp(8),     -- UDP encapsulation
                   atmp(9)
               }
    MAX-ACCESS not-accessible
    STATUS     current
    DESCRIPTION
            "The encapsulation method used by the tunnel."
    ::= { tunnelConfigEntry 3 }

tunnelConfigID OBJECT-TYPE
    SYNTAX     Integer32 (1..2147483647)
    MAX-ACCESS not-accessible
    STATUS     current
    DESCRIPTION
            "An identifier used to distinguish between multiple tunnels
            of the same encapsulation method, with the same endpoints.
            If the encapsulation protocol only allows one tunnel per set
            of endpoint addresses (such as for GRE or IP-in-IP), the
            value of this object is 1.  For encapsulation methods (such
            as L2F) which allow multiple parallel tunnels, the manager
            is responsible for choosing any ID which does not conflict
            with an existing row, such as choosing a random number."
    ::= { tunnelConfigEntry 4 }

tunnelConfigIfIndex OBJECT-TYPE
    SYNTAX     InterfaceIndexOrZero
    MAX-ACCESS read-only
    STATUS     current
    DESCRIPTION
            "If the value of tunnelConfigStatus for this row is active,
            then this object contains the value of ifIndex corresponding
            to the tunnel interface.  A value of 0 is not legal in the
            active state, and means that the interface index has not yet
            been assigned."
    ::= { tunnelConfigEntry 5 }

tunnelConfigStatus OBJECT-TYPE

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    SYNTAX     RowStatus
    MAX-ACCESS read-create
    STATUS     current
    DESCRIPTION
            "The status of this row, by which new entries may be
            created, or old entries deleted from this table. The agent
            need not support setting this object to createAndWait or
            notInService since there are no other writable objects in
            this table, and writable objects in rows of corresponding
            tables such as the tunnelIfTable may be modified while this
            row is active.

            To create a row in this table for an encapsulation method
            which does not support multiple parallel tunnels with the
            same endpoints, the management station should simply use a
            tunnelConfigID of 1, and set tunnelConfigStatus to
            createAndGo.  For encapsulation methods such as L2F which
            allow multiple parallel tunnels, the management station may
            select a pseudo-random number to use as the tunnelConfigID
            and set tunnelConfigStatus to createAndGo.  In the event
            that this ID is already in use and an inconsistentValue is
            returned in response to the set operation, the management
            station should simply select a new pseudo-random number and
            retry the operation.

            Creating a row in this table will cause an interface index
            to be assigned by the agent in an implementation-dependent
            manner, and corresponding rows will be instantiated in the
            ifTable and the tunnelIfTable.  The status of this row will
            become active as soon as the agent assigns the interface
            index, regardless of whether the interface is operationally
            up.

            Deleting a row in this table will likewise delete the
            corresponding row in the ifTable and in the tunnelIfTable."
    ::= { tunnelConfigEntry 6 }

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-- conformance information

tunnelMIBConformance
                  OBJECT IDENTIFIER ::= { tunnelMIB 2 }
tunnelMIBCompliances
                  OBJECT IDENTIFIER ::= { tunnelMIBConformance 1 }
tunnelMIBGroups  OBJECT IDENTIFIER ::= { tunnelMIBConformance 2 }

-- compliance statements

tunnelMIBCompliance MODULE-COMPLIANCE
    STATUS  current
    DESCRIPTION
            "The compliance statement for the IP Tunnel MIB."
    MODULE  -- this module
    MANDATORY-GROUPS { tunnelMIBBasicGroup }

        OBJECT      tunnelIfHopLimit
        MIN-ACCESS  read-only
        DESCRIPTION
            "Write access is not required."

        OBJECT      tunnelIfTOS
        MIN-ACCESS  read-only
        DESCRIPTION
            "Write access is not required."

        OBJECT      tunnelConfigStatus
        MIN-ACCESS  read-only
        DESCRIPTION
            "Write access is not required."
   ::= { tunnelMIBCompliances 1 }

-- units of conformance

tunnelMIBBasicGroup OBJECT-GROUP
    OBJECTS { tunnelIfLocalAddress, tunnelIfRemoteAddress,
       tunnelIfEncapsMethod, tunnelIfHopLimit, tunnelIfTOS,
       tunnelIfSecurity, tunnelConfigIfIndex, tunnelConfigStatus }
    STATUS  current
    DESCRIPTION
            "A collection of objects to support basic management of IP
            Tunnels."
    ::= { tunnelMIBGroups 1 }

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END

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6.  Security Considerations

This MIB contains readable objects whose values provide information
related to IP tunnel interfaces.  There are also a number of objects
that have a MAX-ACCESS clause of read-write and/or read-create, such as
those which allow an administrator to dynamically configure tunnels.

While unauthorized access to the readable objects is relatively
innocuous, unauthorized access to the write-able objects could cause a
denial of service, or could cause unauthorized creation and/or
manipulation of tunnels. Hence, the support for SET operations in a
non-secure environment without proper protection can have a negative
effect on network operations.

SNMPv1 by itself is such an insecure environment.  Even if the network
itself is secure (for example by using IPSec [24]), even then, there is
no control as to who on the secure network is allowed to access and SET
(change/create/delete) the objects in this MIB.

It is recommended that the implementers consider the security features
as provided by the SNMPv3 framework.  Specifically, the use of the
User-based Security Model RFC 2574 [12] and the View-based Access
Control Model RFC 2575 [15] is recommended.

It is then a customer/user responsibility to ensure that the SNMP entity
giving access to this MIB, is properly configured to give access to
those objects only to those principals (users) that have legitimate
rights to access them.

7.  Acknowledgements

This MIB module was updated based on feedback from the IETF's Interfaces
MIB (IF-MIB) and Point-to-Point Protocol Extensions (PPPEXT) Working
Groups.

8.  Author's Address

     Dave Thaler
     Microsoft Corporation
     One Microsoft Way
     Redmond, WA  98052-6399
     Phone: +1 425 703 8835
     EMail: dthaler@microsoft.com

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9.  References

[1]  Wijnen, B., Harrington, D., and R. Presuhn, "An Architecture for
     Describing SNMP Management Frameworks", RFC 2571, Cabletron
     Systems, Inc., BMC Software, Inc., IBM T. J. Watson Research, April
     1999.

[2]  Rose, M., and K. McCloghrie, "Structure and Identification of
     Management Information for TCP/IP-based Internets", STD 16, RFC
     1155, Performance Systems International, Hughes LAN Systems, May
     1990.

[3]  Rose, M., and K. McCloghrie, "Concise MIB Definitions", STD 16, RFC
     1212, Performance Systems International, Hughes LAN Systems, March
     1991.

[4]  M. Rose, "A Convention for Defining Traps for use with the SNMP",
     RFC 1215, Performance Systems International, March 1991.

[5]  McCloghrie, K., Perkins, D., and J. Schoenwaelder, "Structure of
     Management Information Version 2 (SMIv2)", STD 58, RFC 2578, April
     1999.

[6]  McCloghrie, K., Perkins, D., and J. Schoenwaelder, "Textual
     Conventions for SMIv2", STD 58, RFC 2579, April 1999.

[7]  McCloghrie, K., Perkins, D., and J. Schoenwaelder, "Conformance
     Statements for SMIv2", STD 58, RFC 2580, April 1999.

[8]  Case, J., Fedor, M., Schoffstall, M., and J. Davin, "Simple Network
     Management Protocol", STD 15, RFC 1157, SNMP Research, Performance
     Systems International, Performance Systems International, MIT
     Laboratory for Computer Science, May 1990.

[9]  Case, J., McCloghrie, K., Rose, M., and S. Waldbusser,
     "Introduction to Community-based SNMPv2", RFC 1901, SNMP Research,
     Inc., Cisco Systems, Inc., Dover Beach Consulting, Inc.,
     International Network Services, January 1996.

[10] Case, J., McCloghrie, K., Rose, M., and S. Waldbusser, "Transport
     Mappings for Version 2 of the Simple Network Management Protocol
     (SNMPv2)", RFC 1906, SNMP Research, Inc., Cisco Systems, Inc.,
     Dover Beach Consulting, Inc., International Network Services,
     January 1996.

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[11] Case, J., Harrington D., Presuhn R., and B. Wijnen, "Message
     Processing and Dispatching for the Simple Network Management
     Protocol (SNMP)", RFC 2572, SNMP Research, Inc., Cabletron Systems,
     Inc., BMC Software, Inc., IBM T. J. Watson Research, April 1999.

[12] Blumenthal, U., and B. Wijnen, "User-based Security Model (USM) for
     version 3 of the Simple Network Management Protocol (SNMPv3)", RFC
     2574, IBM T. J. Watson Research, April 1999.

[13] Case, J., McCloghrie, K., Rose, M., and S. Waldbusser, "Protocol
     Operations for Version 2 of the Simple Network Management Protocol
     (SNMPv2)", RFC 1905, SNMP Research, Inc., Cisco Systems, Inc.,
     Dover Beach Consulting, Inc., International Network Services,
     January 1996.

[14] Levi, D., Meyer, P., and B. Stewart, "SNMPv3 Applications", RFC
     2573, SNMP Research, Inc., Secure Computing Corporation, Cisco
     Systems, April 1999.

[15] Wijnen, B., Presuhn, R., and K. McCloghrie, "View-based Access
     Control Model (VACM) for the Simple Network Management Protocol
     (SNMP)", RFC 2575, IBM T. J. Watson Research, BMC Software, Inc.,
     Cisco Systems, Inc., April 1999.

[16] Hanks, S., Li, T., Farinacci, D., and P. Traina, "Generic Routing
     Encapsulation (GRE)", RFC 1701, October 1994.

[17] Hanks, S., Li, T., Farinacci, D., and P. Traina, "Generic Routing
     Encapsulation over IPv4 networks", RFC 1702, October 1994.

[18] Perkins, C., "IP Encapsulation within IP", RFC 2003, October 1996.

[19] Perkins, C., "Minimal Encapsulation within IP", RFC 2004, October
     1996.

[20] Hamzeh, Kolar, Littlewood, Pall, Taarud, Valencia, and Verthein,
     "Layer Two Tunneling Protocol (L2TP)", Work in Progress.

[21] Hamzeh, Pall, Verthein, Taarud, and Little, "Point-to-Point
     Tunneling Protocol--PPTP", Work in Progress.

[22] K. Hamzeh.  "Ascend Tunnel Management Protocol - ATMP", RFC 2107,
     February 1997.

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[23] McCloghrie, K., and F. Kastenholz.  "The Interfaces Group MIB using
     SMIv2", RFC 2233, November 1997.

[24] R. Atkinson.  "Security architecture for the internet protocol",
     RFC 2401, November 1998.

[25] Valencia, A., Littlewood, M., and T. Kolar.  "Cisco Layer Two
     Forwarding (Protocol) "L2F"", RFC 2341, May 1998.

[26] D. Provan.  "Tunneling IPX Traffic through IP Networks", RFC 1234,
     June 1991.

[27] Gilligan, R., and E. Nordmark.  "Transition Mechanisms for IPv6
     Hosts and Routers", RFC 1933, April 1996.

[28] Woodburn, R., and D. Mills, "A Scheme for an Internet Encapsulation
     Protocol: Version 1", RFC 1241, July 1991.

[29] Nichols, K., Blake, S., Baker, F., and D. Black.  "Definition of
     the Differentiated Services Field (DS Field) in the IPv4 and IPv6
     Headers", RFC 2474, December 1998.

10.  Full Copyright Statement

Copyright (C) The Internet Society (1999).  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 implmentation 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
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Expires December 1999                                          [Page 18]

Draft                        IP Tunnel MIB                     June 1999

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."

Table of Contents

1 Abstract ........................................................    1
2 Introduction ....................................................    2
3 The SNMP Network Management Framework ...........................    2
4 Overview ........................................................    3
4.1 Relationship to the Interfaces MIB ............................    3
4.1.1 Layering Model ..............................................    4
4.1.2 ifRcvAddressTable ...........................................    4
4.1.3 ifEntry .....................................................    4
5 Definitions .....................................................    6
6 Security Considerations .........................................   15
7 Acknowledgements ................................................   15
8 Author's Address ................................................   15
9 References ......................................................   16
10 Full Copyright Statement .......................................   18

Expires December 1999                                          [Page 19]


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