RFC7856

From RFC-Wiki

Internet Engineering Task Force (IETF) Y. Cui Request for Comments: 7856 J. Dong Category: Standards Track P. Wu ISSN: 2070-1721 M. Xu

                                                 Tsinghua University
                                                       A. Yla-Jaaski
                                                    Aalto University
                                                            May 2016
        Softwire Mesh Management Information Base (MIB)

Abstract

This memo defines a portion of the Management Information Base (MIB) for use with network management protocols in the Internet community. In particular, it defines objects for managing a softwire mesh.

Status of This Memo

This is an Internet Standards Track document.

This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 5741.

Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc7856.

Copyright Notice

Copyright (c) 2016 IETF Trust and the persons identified as the document authors. All rights reserved.

This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.

Introduction

The softwire mesh framework RFC5565 is a tunneling mechanism that enables connectivity between islands of IPv4 networks across a single IPv6 backbone and vice versa. In a softwire mesh, extended Multiprotocol BGP (MP-BGP) is used to set up tunnels and advertise prefixes among Address Family Border Routers (AFBRs).

This memo defines a portion of the Management Information Base (MIB) for use with network management protocols in the Internet community. In particular, it defines objects for managing a softwire mesh RFC5565.

The Internet-Standard Management Framework

For a detailed overview of the documents that describe the current Internet-Standard Management Framework, please refer to section 7 of RFC 3410 RFC3410.

Managed objects are accessed via a virtual information store, termed the Management Information Base or MIB. MIB objects are generally accessed through the Simple Network Management Protocol (SNMP). Objects in the MIB are defined using the mechanisms defined in the Structure of Management Information (SMI). This memo specifies a MIB

module that is compliant to the SMIv2, which is described in STD 58, RFC 2578 RFC2578, STD 58, RFC 2579 RFC2579 and STD 58, RFC 2580 RFC2580.

Terminology

This document uses terminology from the softwire problem statement RFC4925, the BGP encapsulation Subsequent Address Family Identifier (SAFI), the BGP tunnel encapsulation attribute RFC5512, the softwire mesh framework RFC5565, and the BGP IPsec tunnel encapsulation attribute RFC5566.

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 RFC2119.

Structure of the MIB Module

The Softwire Mesh MIB provides a method to monitor the softwire mesh objects through SNMP.

The swmSupportedTunnelTable Subtree

The swmSupportedTunnelTable subtree provides the information about what types of tunnels can be used for softwire mesh scenarios in the AFBR. The softwire mesh framework RFC5565 does not mandate the use of any particular tunneling technology. Based on the BGP tunnel encapsulation attribute tunnel types introduced by RFC 5512 RFC5512 and RFC 5566 RFC5566, the softwire mesh tunnel types include at least L2TPv3 (Layer 2 Tunneling Protocol version 3) over IP, GRE (Generic Routing Encapsulation), Transmit tunnel endpoint, IPsec in Tunnel-mode, IP in IP tunnel with IPsec Transport Mode, MPLS-in-IP tunnel with IPsec Transport Mode, and IP in IP. The detailed encapsulation information of different tunnel types (e.g., L2TPv3 Session ID, GRE Key, etc.) is not managed in the Softwire Mesh MIB.

The swmEncapsTable Subtree

The swmEncapsTable subtree provides softwire mesh NLRI-NH information (Network Layer Reachability Information - Next Hop) about the AFBR. It keeps the mapping between the External-IP (E-IP) prefix and the Internal-IP (I-IP) address of the next hop. The mappings determine which I-IP destination address will be used to encapsulate the received packet according to its E-IP destination address. The definitions of E-IP and I-IP are explained in Section 4.1 of RFC 5565 RFC5565. The number of entries in swmEncapsTable shows how many softwire mesh tunnels are maintained in this AFBR.

The swmBGPNeighborTable Subtree

This subtree provides the softwire mesh BGP neighbor information of an AFBR. It includes the address of the softwire mesh BGP peer and the kind of tunnel that the AFBR would use to communicate with this BGP peer.

The swmConformance Subtree

This subtree provides the conformance information of MIB objects.

Relationship to Other MIB Modules

Relationship to the IF-MIB

The Interfaces MIB RFC2863 defines generic managed objects for managing interfaces. Each logical interface (physical or virtual) has an ifEntry. Tunnels are handled by creating logical interfaces (ifEntry). Being a tunnel, the softwire mesh interface has an entry in the Interface MIB, as well as an entry in the IP Tunnel MIB. Those corresponding entries are indexed by ifIndex.

The ifOperStatus in the ifTable represents whether the mesh function of the AFBR has been triggered. If the softwire mesh capability is negotiated during the BGP OPEN phase, the mesh function is considered to be started, and the ifOperStatus is "up". Otherwise, the ifOperStatus is "down".

In the case of an IPv4-over-IPv6 softwire mesh tunnel, ifInUcastPkts counts the number of IPv6 packets that are sent to the virtual interface for decapsulation into IPv4. The ifOutUcastPkts counts the number of IPv6 packets that are generated by encapsulating IPv4 packets sent to the virtual interface. In particular, if these IPv4 packets need fragmentation, ifOutUcastPkts counts the number of packets after fragmentation.

In the case of an IPv6-over-IPv4 softwire mesh tunnel, ifInUcastPkts counts the number of IPv4 packets that are delivered to the virtual interface for decapsulation into IPv6. The ifOutUcastPkts counts the number of IPv4 packets that are generated by encapsulating IPv6 packets sent down to the virtual interface. In particular, if these IPv6 packets need to be fragmented, ifOutUcastPkts counts the number of packets after fragmentation. Similar definitions apply to other counter objects in the ifTable.

Relationship to the IP Tunnel MIB

The IP Tunnel MIB RFC4087 contains objects applicable to all IP tunnels, including softwire mesh tunnels. Meanwhile, the Softwire Mesh MIB extends the IP Tunnel MIB to further describe encapsulation- specific information.

When running a point-to-multipoint tunnel, it is necessary for a softwire mesh AFBR to maintain an encapsulation table in order to perform correct "forwarding" among AFBRs. This forwarding function on an AFBR is performed by using the E-IP destination address to look up the I-IP encapsulation destination address in the encapsulation table. An AFBR also needs to know the BGP peer information of the other AFBRs, so that it can negotiate the NLRI-NH information and the tunnel parameters with them.

The Softwire Mesh MIB requires the implementation of the IP Tunnel MIB. The tunnelIfEncapsMethod in the tunnelIfEntry MUST be set to softwireMesh(16), and a corresponding entry in the Softwire Mesh MIB module will be presented for the tunnelIfEntry. The tunnelIfRemoteInetAddress MUST be set to "0.0.0.0" for IPv4 or "::" for IPv6 because it is a point-to-multipoint tunnel.

The tunnelIfAddressType in the tunnelIfTable represents the type of address in the corresponding tunnelIfLocalInetAddress and tunnelIfRemoteInetAddress objects. The tunnelIfAddressType is identical to swmEncapsIIPDstType in softwire mesh, which can support either IPv4-over-IPv6 or IPv6-over-IPv4. When the swmEncapsEIPDstType is IPv6 and the swmEncapsIIPDstType is IPv4, the tunnel type is IPv6-over-IPv4; when the swmEncapsEIPDstType is IPv4 and the swmEncapsIIPDstType is IPv6, the encapsulation mode is IPv4- over-IPv6.

MIB Modules Required for IMPORTS

The following MIB module IMPORTS objects from SNMPv2-SMI RFC2578, SNMPv2-CONF RFC2580, IF-MIB RFC2863, and INET-ADDRESS-MIB RFC4001.

Definitions

SOFTWIRE-MESH-MIB DEFINITIONS ::= BEGIN

IMPORTS

   MODULE-IDENTITY, OBJECT-TYPE, mib-2 FROM SNMPv2-SMI
   OBJECT-GROUP, MODULE-COMPLIANCE             FROM SNMPv2-CONF
   InetAddress, InetAddressType, InetAddressPrefixLength
   FROM INET-ADDRESS-MIB
   ifIndex                                FROM IF-MIB
   IANAtunnelType                         FROM IANAifType-MIB;
   swmMIB MODULE-IDENTITY
   LAST-UPDATED "201605110000Z"        -- May 11, 2016
   ORGANIZATION "Softwire Working Group"
   CONTACT-INFO
            "Yong Cui
             Email:  [email protected]
             Jiang Dong
             Email:  [email protected]
             Peng Wu
             Email:  [email protected]
             Mingwei Xu
             Email:  [email protected]
             Antti Yla-Jaaski
             Email:  [email protected]
             Email comments directly to the Softwire WG Mailing
             List at [email protected]
            "
   DESCRIPTION
          "This MIB module contains managed object definitions for
           the softwire mesh framework.
           Copyright (c) 2016 IETF Trust and the persons
           identified as authors of the code.  All rights reserved.
           Redistribution and use in source and binary forms, with
           or without modification, is permitted pursuant to, and
           subject to the license terms contained in, the Simplified
           BSD License set forth in Section 4.c of the IETF Trust's
           Legal Provisions Relating to IETF Documents
           (http://trustee.ietf.org/license-info)."
   REVISION    "201605110000Z"
   DESCRIPTION "Initial version, published as RFC 7856"
   ::= { mib-2 239 }

swmObjects OBJECT IDENTIFIER ::= { swmMIB 1 }

-- swmSupportedTunnelTable swmSupportedTunnelTable OBJECT-TYPE

   SYNTAX      SEQUENCE OF SwmSupportedTunnelEntry
   MAX-ACCESS  not-accessible
   STATUS      current
   DESCRIPTION
       "A table of objects that show what kinds of tunnels
       can be supported by the AFBR."
   ::= { swmObjects 1 }

swmSupportedTunnelEntry OBJECT-TYPE

   SYNTAX      SwmSupportedTunnelEntry
   MAX-ACCESS  not-accessible
   STATUS      current
   DESCRIPTION
       "A set of objects that show what kinds of tunnels
       can be supported in the AFBR.  If the AFBR supports
       multiple tunnel types, the swmSupportedTunnelTable
       would have several entries."
   INDEX { swmSupportedTunnelType }
   ::= { swmSupportedTunnelTable 1 }

SwmSupportedTunnelEntry ::= SEQUENCE {

   swmSupportedTunnelType              IANAtunnelType

}

swmSupportedTunnelType OBJECT-TYPE

   SYNTAX      IANAtunnelType
   MAX-ACCESS  read-only
   STATUS      current
   DESCRIPTION
       "Represents the tunnel type that can be used for softwire
       mesh scenarios, such as L2TPv3 over IP, GRE, Transmit
       tunnel endpoint, IPsec in Tunnel-mode, IP in IP tunnel with
       IPsec Transport Mode, MPLS-in-IP tunnel with IPsec Transport
       Mode, and IP in IP.  There is no restriction on the tunnel
       type the softwire mesh can use."
    REFERENCE
       "L2TPv3 over IP, GRE, and IP in IP in RFC 5512.
       Transmit tunnel endpoint, IPsec in Tunnel-mode, IP in IP
       tunnel with IPsec Transport Mode, MPLS-in-IP tunnel with
       IPsec Transport Mode in RFC 5566."
   ::= { swmSupportedTunnelEntry 1 }

-- end of swmSupportedTunnelTable

--swmEncapsTable swmEncapsTable OBJECT-TYPE

   SYNTAX      SEQUENCE OF SwmEncapsEntry
   MAX-ACCESS  not-accessible
   STATUS      current
   DESCRIPTION
       "A table of objects that display the
       softwire mesh encapsulation information."
   ::= { swmObjects 2 }

swmEncapsEntry OBJECT-TYPE

   SYNTAX      SwmEncapsEntry
   MAX-ACCESS  not-accessible
   STATUS      current
   DESCRIPTION
       "A table of objects that manage the softwire mesh I-IP
        encapsulation destination based on the E-IP destination
        prefix."
   INDEX { ifIndex,
           swmEncapsEIPDstType,
           swmEncapsEIPDst,
           swmEncapsEIPPrefixLength
         }
   ::= { swmEncapsTable 1 }

SwmEncapsEntry ::= SEQUENCE {

   swmEncapsEIPDstType       InetAddressType,
   swmEncapsEIPDst           InetAddress,
   swmEncapsEIPPrefixLength  InetAddressPrefixLength,
   swmEncapsIIPDstType       InetAddressType,
   swmEncapsIIPDst           InetAddress

}

swmEncapsEIPDstType OBJECT-TYPE

   SYNTAX      InetAddressType
   MAX-ACCESS  not-accessible
   STATUS      current
   DESCRIPTION
       "This object specifies the address type used for
       swmEncapsEIPDst.  It is different from the
       tunnelIfAddressType in the tunnelIfTable.  The
       swmEncapsEIPDstType is IPv6 (2) if it is IPv6-over-IPv4
       tunneling.  The swmEncapsEIPDstType is
       IPv4 (1) if it is IPv4-over-IPv6 tunneling."
   REFERENCE
       "IPv4 and IPv6 in RFC 4001."
   ::= { swmEncapsEntry 1 }

swmEncapsEIPDst OBJECT-TYPE

   SYNTAX      InetAddress
   MAX-ACCESS  not-accessible
   STATUS      current
   DESCRIPTION
       "The E-IP destination prefix, which is
       used for I-IP encapsulation destination looking up.
       The type of this address is determined by the
       value of swmEncapsEIPDstType"
   REFERENCE
       "E-IP and I-IP in RFC 5565."
   ::= { swmEncapsEntry 2 }

swmEncapsEIPPrefixLength OBJECT-TYPE

   SYNTAX      InetAddressPrefixLength
   MAX-ACCESS  not-accessible
   STATUS      current
   DESCRIPTION
       "The prefix length of the E-IP destination prefix."
   ::= { swmEncapsEntry 3 }

swmEncapsIIPDstType OBJECT-TYPE

   SYNTAX      InetAddressType
   MAX-ACCESS  read-only
   STATUS      current
   DESCRIPTION
       "This object specifies the address type used for
        swmEncapsIIPDst.  It is the same as the tunnelIfAddressType
        in the tunnelIfTable."
   REFERENCE
       "IPv4 and IPv6 in RFC 4001."
   ::= { swmEncapsEntry 4 }

swmEncapsIIPDst OBJECT-TYPE

   SYNTAX      InetAddress
   MAX-ACCESS  read-only
   STATUS      current
   DESCRIPTION
       "The I-IP destination address, which is used as the
       encapsulation destination for the corresponding E-IP
       prefix.  Since the tunnelIfRemoteInetAddress in the
       tunnelIfTable should be 0.0.0.0 or ::, swmEncapIIPDst
       should be the destination address used in the outer
       IP header."
   REFERENCE
       "E-IP and I-IP in RFC 5565."
   ::= { swmEncapsEntry 5 }

-- End of swmEncapsTable

-- swmBGPNeighborTable swmBGPNeighborTable OBJECT-TYPE

   SYNTAX      SEQUENCE OF SwmBGPNeighborEntry
   MAX-ACCESS  not-accessible
   STATUS      current
   DESCRIPTION
       "A table of objects that display the softwire mesh
       BGP neighbor information."
   ::= { swmObjects 3 }

swmBGPNeighborEntry OBJECT-TYPE

   SYNTAX      SwmBGPNeighborEntry
   MAX-ACCESS  not-accessible
   STATUS      current
   DESCRIPTION
       "A set of objects that display the softwire mesh
       BGP neighbor information."
   INDEX {
           ifIndex,
           swmBGPNeighborInetAddressType,
           swmBGPNeighborInetAddress
         }
   ::= { swmBGPNeighborTable 1 }

SwmBGPNeighborEntry ::= SEQUENCE {

       swmBGPNeighborInetAddressType    InetAddressType,
       swmBGPNeighborInetAddress        InetAddress,
       swmBGPNeighborTunnelType         IANAtunnelType

}

swmBGPNeighborInetAddressType OBJECT-TYPE

   SYNTAX      InetAddressType
   MAX-ACCESS  not-accessible
   STATUS      current
   DESCRIPTION
       "This object specifies the address type used for
        swmBGPNeighborInetAddress."
   ::= { swmBGPNeighborEntry 1 }

swmBGPNeighborInetAddress OBJECT-TYPE

   SYNTAX      InetAddress
   MAX-ACCESS  not-accessible
   STATUS      current
   DESCRIPTION
       "The address of the AFBR's BGP neighbor.  The
       address type is the same as the tunnelIfAddressType
       in the tunnelIfTable."
   ::= { swmBGPNeighborEntry 2 }

swmBGPNeighborTunnelType OBJECT-TYPE

   SYNTAX      IANAtunnelType
   MAX-ACCESS  read-only
   STATUS      current
   DESCRIPTION
       "Represents the type of tunnel that the AFBR
       chooses to transmit traffic with another AFBR/BGP
       neighbor."
   ::= { swmBGPNeighborEntry 3 }

-- End of swmBGPNeighborTable

-- conformance information swmConformance

                   OBJECT IDENTIFIER ::= { swmMIB 2 }

swmCompliances

                   OBJECT IDENTIFIER ::= { swmConformance 1 }

swmGroups

                   OBJECT IDENTIFIER ::= { swmConformance 2 }
-- compliance statements

swmCompliance MODULE-COMPLIANCE

  STATUS current
  DESCRIPTION
      "Describes the requirements for conformance to the Softwire
      Mesh MIB.
      The following index objects cannot be added as OBJECT
      clauses but nevertheless have compliance requirements:
      "
      -- OBJECT  swmEncapsEIPDstType
      -- SYNTAX  InetAddressType { ipv4(1), ipv6(2) }
      -- DESCRIPTION
      -- "An implementation is required to support
      --  global IPv4 and/or IPv6 addresses, depending
      --  on its support for IPv4 and IPv6."
      -- OBJECT  swmEncapsEIPDst
      -- SYNTAX  InetAddress (SIZE(4|16))
      -- DESCRIPTION
      -- "An implementation is required to support
      --  global IPv4 and/or IPv6 addresses, depending
      --  on its support for IPv4 and IPv6."
      -- OBJECT  swmEncapsEIPPrefixLength
      -- SYNTAX  InetAddressPrefixLength (Unsigned32 (0..128))
      -- DESCRIPTION
      -- "An implementation is required to support
      --  global IPv4 and/or IPv6 addresses, depending
      --  on its support for IPv4 and IPv6."
      -- OBJECT  swmBGPNeighborInetAddressType
      -- SYNTAX  InetAddressType { ipv4(1), ipv6(2) }
      -- DESCRIPTION
      -- "An implementation is required to support
      --  global IPv4 and/or IPv6 addresses, depending
      --  on its support for IPv4 and IPv6."
      -- OBJECT  swmBGPNeighborInetAddress
      -- SYNTAX  InetAddress (SIZE(4|16))
      -- DESCRIPTION
      -- "An implementation is required to support
      --  global IPv4 and/or IPv6 addresses, depending
      --  on its support for IPv4 and IPv6."
  MODULE -- this module
  MANDATORY-GROUPS    {
                        swmSupportedTunnelGroup,
                        swmEncapsGroup,
                        swmBGPNeighborGroup
                      }
  ::= { swmCompliances 1 }

swmSupportedTunnelGroup OBJECT-GROUP

  OBJECTS {
      swmSupportedTunnelType
  }
  STATUS  current
  DESCRIPTION
      "The collection of objects that are used to show
      what kind of tunnel the AFBR supports."
  ::= { swmGroups 1 }

swmEncapsGroup OBJECT-GROUP

  OBJECTS {
       swmEncapsIIPDst,
       swmEncapsIIPDstType
  }
  STATUS  current
  DESCRIPTION
      "The collection of objects that are used to display
      softwire mesh encapsulation information."
  ::= { swmGroups 2 }

swmBGPNeighborGroup OBJECT-GROUP

  OBJECTS {
       swmBGPNeighborTunnelType
  }
  STATUS  current
  DESCRIPTION
      "The collection of objects that are used to display
       softwire mesh BGP neighbor information."
  ::= { swmGroups 3 }

END

Security Considerations

Because this MIB module reuses the IP Tunnel MIB, the security considerations of the IP Tunnel MIB are also applicable to the Softwire Mesh MIB.

There are no management objects defined in this MIB module that have a MAX-ACCESS clause of read-write and/or read-create. So, if this MIB module is implemented correctly, then there is no risk that an intruder can alter or create any management objects of this MIB module via direct SNMP SET operations.

Some of the readable objects in this MIB module (i.e., objects with a MAX-ACCESS other than not-accessible) may be considered sensitive or vulnerable in some network environments. It is thus important to control even GET and/or NOTIFY access to these objects and possibly to even encrypt the values of these objects when sending them over the network via SNMP. These are the objects and their sensitivity/ vulnerability:

swmSupportedTunnelType, swmEncapsIIPDstType, swmEncapsIIPDst, and swmBGPNeighborTunnelType can expose the types of tunnels used within the internal network and potentially reveal the topology of the internal network.

SNMP versions prior to SNMPv3 did not include adequate security. Even if the network itself is secure (for example by using IPsec), there is no control as to who on the secure network is allowed to access and GET/SET (read/change/create/delete) the objects in this MIB module.

Implementations SHOULD provide the security features described by the SNMPv3 framework (see RFC3410), and implementations claiming compliance to the SNMPv3 standard MUST include full support for authentication and privacy via the User-based Security Model (USM) RFC3414 with the AES cipher algorithm RFC3826. Implementations MAY also provide support for the Transport Security Model (TSM) RFC5591 in combination with a secure transport such as SSH RFC5592 or TLS/DTLS RFC6353.

Further, deployment of SNMP versions prior to SNMPv3 is NOT RECOMMENDED. Instead, it is RECOMMENDED to deploy SNMPv3 and to enable cryptographic security. It is then a customer/operator responsibility to ensure that the SNMP entity giving access to an instance of this MIB module is properly configured to give access to the objects only to those principals (users) that have legitimate rights to indeed GET or SET (change/create/delete) them.

IANA Considerations

IANA has allocated the following OBJECT IDENTIFIER value and recorded it in the SMI Numbers registry in the subregistry called "SMI Network Management MGMT Codes Internet-standard MIB" under the mib-2 branch (1.3.6.1.2.1):

       Descriptor        OBJECT IDENTIFIER value
       ----------        -----------------------
       swmMIB            { mib-2 239 }

IANA has recorded the following IANAtunnelType Textual Convention within the IANAifType-MIB:

       IANAtunnelType ::= TEXTUAL-CONVENTION
             SYNTAX     INTEGER {
                        softwireMesh(16)  -- softwire mesh tunnel
                        }

References

Normative References

RFC2119 Bradner, S., "Key words for use in RFCs to Indicate

          Requirement Levels", BCP 14, RFC 2119,
          DOI 10.17487/RFC2119, March 1997,
          <http://www.rfc-editor.org/info/rfc2119>.

RFC2578 McCloghrie, K., Ed., Perkins, D., Ed., and J.

          Schoenwaelder, Ed., "Structure of Management Information
          Version 2 (SMIv2)", STD 58, RFC 2578,
          DOI 10.17487/RFC2578, April 1999,
          <http://www.rfc-editor.org/info/rfc2578>.

RFC2579 McCloghrie, K., Ed., Perkins, D., Ed., and J.

          Schoenwaelder, Ed., "Textual Conventions for SMIv2",
          STD 58, RFC 2579, DOI 10.17487/RFC2579, April 1999,
          <http://www.rfc-editor.org/info/rfc2579>.

RFC2580 McCloghrie, K., Ed., Perkins, D., Ed., and J.

          Schoenwaelder, Ed., "Conformance Statements for SMIv2",
          STD 58, RFC 2580, DOI 10.17487/RFC2580, April 1999,
          <http://www.rfc-editor.org/info/rfc2580>.

RFC3414 Blumenthal, U. and B. Wijnen, "User-based Security Model

          (USM) for version 3 of the Simple Network Management
          Protocol (SNMPv3)", STD 62, RFC 3414,
          DOI 10.17487/RFC3414, December 2002,
          <http://www.rfc-editor.org/info/rfc3414>.

RFC3826 Blumenthal, U., Maino, F., and K. McCloghrie, "The

          Advanced Encryption Standard (AES) Cipher Algorithm in the
          SNMP User-based Security Model", RFC 3826,
          DOI 10.17487/RFC3826, June 2004,
          <http://www.rfc-editor.org/info/rfc3826>.

RFC4001 Daniele, M., Haberman, B., Routhier, S., and J.

          Schoenwaelder, "Textual Conventions for Internet Network
          Addresses", RFC 4001, DOI 10.17487/RFC4001, February 2005,
          <http://www.rfc-editor.org/info/rfc4001>.

RFC5512 Mohapatra, P. and E. Rosen, "The BGP Encapsulation

          Subsequent Address Family Identifier (SAFI) and the BGP
          Tunnel Encapsulation Attribute", RFC 5512,
          DOI 10.17487/RFC5512, April 2009,
          <http://www.rfc-editor.org/info/rfc5512>.

RFC5565 Wu, J., Cui, Y., Metz, C., and E. Rosen, "Softwire Mesh

          Framework", RFC 5565, DOI 10.17487/RFC5565, June 2009,
          <http://www.rfc-editor.org/info/rfc5565>.

RFC5566 Berger, L., White, R., and E. Rosen, "BGP IPsec Tunnel

          Encapsulation Attribute", RFC 5566, DOI 10.17487/RFC5566,
          June 2009, <http://www.rfc-editor.org/info/rfc5566>.

RFC5591 Harrington, D. and W. Hardaker, "Transport Security Model

          for the Simple Network Management Protocol (SNMP)",
          STD 78, RFC 5591, DOI 10.17487/RFC5591, June 2009,
          <http://www.rfc-editor.org/info/rfc5591>.

RFC5592 Harrington, D., Salowey, J., and W. Hardaker, "Secure

          Shell Transport Model for the Simple Network Management
          Protocol (SNMP)", RFC 5592, DOI 10.17487/RFC5592, June
          2009, <http://www.rfc-editor.org/info/rfc5592>.

RFC6353 Hardaker, W., "Transport Layer Security (TLS) Transport

          Model for the Simple Network Management Protocol (SNMP)",
          STD 78, RFC 6353, DOI 10.17487/RFC6353, July 2011,
          <http://www.rfc-editor.org/info/rfc6353>.

Informative References

RFC2863 McCloghrie, K. and F. Kastenholz, "The Interfaces Group

          MIB", RFC 2863, DOI 10.17487/RFC2863, June 2000,
          <http://www.rfc-editor.org/info/rfc2863>.

RFC3410 Case, J., Mundy, R., Partain, D., and B. Stewart,

          "Introduction and Applicability Statements for Internet-
          Standard Management Framework", RFC 3410,
          DOI 10.17487/RFC3410, December 2002,
          <http://www.rfc-editor.org/info/rfc3410>.

RFC4087 Thaler, D., "IP Tunnel MIB", RFC 4087,

          DOI 10.17487/RFC4087, June 2005,
          <http://www.rfc-editor.org/info/rfc4087>.

RFC4925 Li, X., Ed., Dawkins, S., Ed., Ward, D., Ed., and A.

          Durand, Ed., "Softwire Problem Statement", RFC 4925,
          DOI 10.17487/RFC4925, July 2007,
          <http://www.rfc-editor.org/info/rfc4925>.

Acknowledgements

The authors would like to thank Dave Thaler, Jean-Philippe Dionne, Qi Sun, Sheng Jiang, and Yu Fu for their valuable comments.

Authors' Addresses

Yong Cui Tsinghua University Department of Computer Science, Tsinghua University Beijing 100084 China

Phone: +86-10-6260-3059 Email: [email protected]

Jiang Dong Tsinghua University Department of Computer Science, Tsinghua University Beijing 100084 China

Phone: +86-10-6278-5822 Email: [email protected]

Peng Wu Tsinghua University Department of Computer Science, Tsinghua University Beijing 100084 China

Phone: +86-10-6278-5822 Email: [email protected]

Mingwei Xu Tsinghua University Department of Computer Science, Tsinghua University Beijing 100084 China

Phone: +86-10-6278-5822 Email: [email protected]

Antti Yla-Jaaski Aalto University Konemiehentie 2 Espoo 02150 Finland

Phone: +358-40-5954222 Email: [email protected]