MSEC Working Group                                               B. Weis
Internet-Draft                                                 S. Rowles
Intended status: Standards Track                           Cisco Systems
Expires: March 15, 2012                               September 12, 2011


            GDOI Generic Message Authentication Code Policy
                       draft-weis-gdoi-mac-tek-03

Abstract

   A number of IETF signaling and routing applications require a set of
   devices to share the same policy and keying material and include a
   message authentication code in their protocols packets for
   authentication .  It is often beneficial for this keying material to
   be chosen dynamically using a group key management protocol.  This
   memo describes the policy required for the Group Domain of
   Interpretation (GDOI) group key management system to distribute a
   message authentication code key and associated policy.

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   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."

   This Internet-Draft will expire on March 15, 2012.

Copyright Notice

   Copyright (c) 2011 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
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   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



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   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.


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1.  Scope  . . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.2.  Requirements notation  . . . . . . . . . . . . . . . . . .  3

   2.  GDOI Discussion  . . . . . . . . . . . . . . . . . . . . . . .  4

   3.  New GDOI Payload Definitions . . . . . . . . . . . . . . . . .  5
     3.1.  Message Authentication Code Policy SA TEK  . . . . . . . .  5
       3.1.1.  Application Types  . . . . . . . . . . . . . . . . . .  6
       3.1.2.  MAC Algorithm Types  . . . . . . . . . . . . . . . . .  7
       3.1.3.  Anti-Replay Types  . . . . . . . . . . . . . . . . . .  7
       3.1.4.  Application-Specific Policy Attributes . . . . . . . .  7
     3.2.  Key Packet definition for MACs . . . . . . . . . . . . . .  7

   4.  RSVP . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  9
     4.1.  RSVP SA TEK Policy . . . . . . . . . . . . . . . . . . . .  9
     4.2.  Anti-Replay Discussion . . . . . . . . . . . . . . . . . .  9
     4.3.  Application-specific attributes  . . . . . . . . . . . . . 10

   5.  NLS  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
     5.1.  NLS SA TEK Policy  . . . . . . . . . . . . . . . . . . . . 11
     5.2.  Application-specific attributes  . . . . . . . . . . . . . 11

   6.  Requirements for adding additional application support . . . . 12

   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 13

   8.  Security Considerations  . . . . . . . . . . . . . . . . . . . 15

   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 16
     9.1.  Normative References . . . . . . . . . . . . . . . . . . . 16
     9.2.  Informative References . . . . . . . . . . . . . . . . . . 16

   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 18










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1.  Introduction

   The Group Domain of Interpretation (GDOI) [I-D.ietf-msec-gdoi-update]
   is a group key management protocol fitting into the Multicast
   Security Group Key Management Architecture [RFC3740].  GDOI is used
   to disseminate group security policy and keying material to group
   members for use with a particular cryptographic system.  GDOI
   describes the distribution of group security policy and keying
   material for network traffic protected by IPsec [RFC4301], however
   group security policy and keying material for other types of
   cryptographic systems can also be distributed by GDOI as well.

   A number of transport and routing protocol specifications specify a
   MAC to provide packet authentication between devices.  When the
   protocol instantiation includes a group of devices, they all need to
   share a common set of authentication policy and keying material to
   create and validate the Message Authentication Code (MAC) included in
   protocol packets.  The requirements for each of the protocol
   specifications are generally similar.  This document describes how
   GDOI can be used to distribute the group authentication policy and
   keying material for these protocols.

   This memo refers to candidate protocol specifications as
   "applications" of the GDOI Generic Message Authentication Code
   Policy.  Policy distribution for two applications is described:
   Resource reSerVation Protocol (RSVP) and Network Layer Signaling
   (NLS).

1.1.  Scope

   This memo is intended to provide policy for applications not
   specifying the use of ESP [RFC4303] or AH [RFC4302] for
   authentication.  Such applications SHOULD use the relevant payload
   definitions described in [I-D.ietf-msec-gdoi-update].  Group
   applications requiring the use of encryption MUST NOT use payloads
   described in this memo, and are encouraged to use ESP.

1.2.  Requirements notation

   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].









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2.  GDOI Discussion

   This section provides a short informative discussion of the GDOI
   group key management protocol.  For definitive information regarding
   the GDOI protocol, please refer to [I-D.ietf-msec-gdoi-update].  For
   more information on group security, please refer to RFC 3740.

   The GDOI group key management protocol actively manages security
   policy and keying material for a set of group members.  GDOI begins
   operation when a client application on the group member initiates a
   request to the GDOI subsystem on the group member.  The GDOI
   subsystem "registers" to a GDOI Group Controller/Key Server (GCKS)
   device using the GROUPKEY_PULL protocol.  The group member and GCKS
   setup a private and authenticated exchange.  After successful
   authentication and authorization, the GCKS provides group security
   policy and keying material to the GDOI subsystem on the group member.
   When the GDOI subsystem on the group member receives both security
   policy and keying material, it makes it available to the client
   application on the device that originally requested the MAC policy.

   The GDOI key server also distributes policy and keys that describe
   how it will distribute updates to group policy over time.  Described
   in GDOI as the GROUPKEY_PUSH message, it is more generally known as a
   "rekey" message.  Rekey messages are typically distributed as IP
   multicast packets.  They provide replacement security policy and
   keying material to group members (e.g., prior to a key expiration) or
   to revoke group members in a manner that is non-disruptive to the
   extant group members.























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3.  New GDOI Payload Definitions

   The following sections describe how the GDOI Generic Message
   Authentication Code Policy is applied to GDOI protocol payloads.
   There are two affected payloads: the Security Association (SA)
   payload and the Key Download (KD) payload.

   The GDOI SA payload includes a set of SA attribute payloads,
   including an SA attribute payload which distributes a definition of
   the traffic to be secured.  This payload is known as the SA TEK.
   This memo describes a new type of SA TEK for distributing GDOI
   Generic Message Authentication Code Policy.  For more information on
   the SA TEK attribute payload, please refer to Section 5.5 of
   [I-D.ietf-msec-gdoi-update].

   The GDOI KD payload carries keying material associated with policy
   previously distributed in SA attribute payloads.  This memo does not
   define any new types of key policy for the Message Authentication
   Protocol Policy, but does place restrictions on the types of keys
   that can be distributed.

3.1.   Message Authentication Code Policy SA TEK

   This section describes the SA TEK payload used to distribute MAC
   policy.  Protocols that use a MAC typically define a limited number
   of policy attributes associated with the MAC.  These policy
   attributes are described in the MAC SA TEK.

   The GDOI subsystem on a group member must maintain separation between
   client applications, and as such needs to know what application
   requested a particular set of policy.  Thus, the SA TEK includes an
   Application field naming the correct application with the group
   member.  In some instances, client applications define additional
   policy, and this policy is described in a set of application-specific
   policy attributes attached to the SA TEK.

   A GDOI key server may distribute more than on SA TEK for a particular
   Application.  In particular, the Application-Specific Policy
   Attributes may describe discrete instances of an application.












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        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
       !           Application         | MAC Algorithm !  Anti-Replay  !
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
       !                         Key Lifetime                          !
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       !   SPI Size    !                     SPI                       ~
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
       !           Application-Specific Policy Attributes              ~
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!

   The SA TEK Payload fields are defined as follows:

   o  Application (2 octets -- Value describing the client application.
      Application types are defined below.  Values are defined in the
      IANA Considerations section.

   o  MAC Algorithm (1 octet) -- Value specifying which Message
      Authentication Code (MAC) used to generate MAC.  MAC Algorithm
      types are defined below.  Values are defined in the IANA
      Considerations section.

   o  Anti-Replay (1 octet) -- Value specifying the type of anti-replay
      protection that is used with this application.  Anti-replay types
      are defined below.  Values are defined in the IANA Considerations
      section.

   o  Key Lifetime (4 octets) -- Value specifying the remaining lifetime
      of the SA TEK, in seconds.  A time of zero indicates that the use
      of this policy does not terminate based on time.

   o  SPI Size (1 octet) -- Length (in octets) of the SPI associated
      with this SA TEK.

   o  SPI (Variable) -- Value describing the identity of the key.  The
      key identifier uniquely defines an SA TEK.

   o  Application-Specific Policy Attributes (Variable) -- TLV policy
      attributes specific to this application.  These attributes are
      defined by client application-specific policy.

3.1.1.  Application Types

   The following Client Applications are defined for use with the MAC SA
   TEK.





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   o  RSVP.  The Resource reSerVation Protocol [RFC3097]

   o  NLS.  Network Layer Signaling protocol [I-D.shore-nls-tl]

   Other protocols may be defined for use with the Generic Message
   Authentication Code Policy SA TEK.  However, they must first satisfy
   the requirements described in Section 4.

3.1.2.  MAC Algorithm Types

   The following MAC algorithms are defined for use with this TEK.

   o  HMAC-MD5.  The MD5 algorithm used with an HMAC construction
      [RFC2104].  This MAC algorithm is considered weak, but is required
      by some protocols.

   o  HMAC-SHA1-96.  The SHA1 algorithm used with an HMAC construction,
      with a length truncated to 96 bits.[RFC2104].

3.1.3.  Anti-Replay Types

   The following methods of constructing sequence numbers is defined for
   use with this TEK.

   o  NONE.  This value indicates that no anti-replay protection is used
      with this TEK.

   o  COUNTER.  Counters (also known as sequence numbers) provide anti-
      replay protection in an application-specific manner.

   o  TIME.  Values from a clock are used for replay protection in an
      application-specific manner.

3.1.4.  Application-Specific Policy Attributes

   Application-Specific Attributes are defined for each application that
   requires them.  The attributes must follow the format defined in
   ISAKMP [RFC2408] Section 3.3.  In the table, attributes that are
   defined as TV are marked as Basic (B); attributes that are defined as
   TLV are marked as Variable (V).  Values are defined in the IANA
   Considerations section.

3.2.  Key Packet definition for MACs

   Keying material is distributed in a Key Packet as part of the GDOI KD
   payload.  The Key packet is formed as follows.





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   o  KD Type.  The type of KD MUST be TEK.

   o  SPI.  The SPI from the SA TEK is placed in the SPI field.

   o  Key. The keying material for the MAC algorithm is placed in a
      TEK_INTEGRITY_KEY attribute.

   The Key Packet MUST NOT contain a TEK_ALGORITHM_KEY or
   TEK_SOURCE_AUTH_KEY attribute.










































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4.  RSVP

   The RSVP protocol provides a means for establishing resource
   reservations between cooperating systems.  To ensure the integrity of
   the associated reservation and admission control mechanisms, the RSVP
   INTEGRITY Option defined in [RFC2747] and [RFC3097] may be used.
   These protect RSVP message integrity hop-by-hop and provide node
   authentication as well as replay protection, thereby protecting
   against corruption and spoofing of RSVP messages.  In some network
   configurations, a group of cooperating devices exchange RSVP packets
   such that the sender of an RSVP packet cannot determine a priori
   which RSVP device will be receiving it.  These cooperating devices
   can benefit from sharing the same group policy and keying material.
   [I-D.ietf-tsvwg-rsvp-security-groupkeying] presents a framework for
   RSVP security using dynamic group keying and discusses its
   applicability.  In line with this framework, this section describes
   extensions to GDOI for distribution of security policy and keying
   material for RSVP.

   The policy distributed in this section meets the key management
   assumptions made by the RSVP Security Properties memo [RFC4230].

4.1.  RSVP SA TEK Policy

   The following describes how the RSVP Integrity object policy is
   represented in the MAC SA TEK payload.

   o  MAC Algorithm.  This field maps to the Keyed Message Digest field
      of the RFC 2747 INTEGRITY Object.  Supported algorithms are: HMAC-
      MD5 and HMAC-SHA1-96.

   o  Anti-Replay.  COUNTER and TIME types are both valid types of anti-
      replay protection.  See a discussion of how they are used below.

   o  Key Lifetime.  If the KeyStartValid optional attribute is included
      in the SA TEK, this lifetime specifies the entire lifetime of the
      SA TEK.  Otherwise, it represents the partial remaining lifetime.

   o  SPI.  This field matches the Key Identifier in the RFC 2747
      INTEGRITY Object, and

   o  SPI Size.  The length of the SPI MUST be 1 to 6 octets.

4.2.  Anti-Replay Discussion

   COUNTER corresponds to the Simple Sequence Numbers method defined in
   Section 3.1 of RFC 2747.  When COUNTER based sequence numbers are
   used, each group member maintains its own sequence number for a given



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   group in order to set the sequence number field in RSVP messages
   generated in this group.  Therefore, an RSVP receiver MUST track
   received sequence numbers separately for each RSVP neighbour in order
   to reliably distinguish between new and replay messages.

   TIME corresponds to the Sequence Numbers Based on a Real Time Clock
   method described in Section 3.2 of RFC 2747 or the Sequence Numbers
   Based on a Network Recovered Clock method described in Section 3.3 or
   RFC 2747.

4.3.  Application-specific attributes

   o  KeyStartValid (V).  This attribute specifies an real time in the
      future when the TEK will take effect [RFC2747].  Note that the
      corresponding KeyEndValid time defined in RFC 2747 is not
      distributed by GDOI, but is computed by adding the Key Lifetime
      value to KeyStartValid.  The KeyStartValid value is represented as
      the number of seconds since 0 hours, 0 minutes, 0 seconds, January
      1, 1970.
































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5.  NLS

   NLS [I-D.shore-nls-tl] is a core protocol for a generalized on-path
   request protocol that is being used today to carry topology discovery
   and other requests.  NLS specifies the use of group security, where
   group members share a MAC key.  A MAC result is carried in the NLS
   A_RESPONSE and B_RESPONSE TLVs, which consummate authenticated nonce
   exchanges.  A MAC result is also carried in the NLS AUTHENTICATION
   TLV, which is used to ensure integrity of NLS messages.  This TLV
   also includes a Sequence Number for anti-replay protection.  NLS
   associates a set of Application Group IDs (AGIDs) with a particular
   MAC key.  Each AGID represents a unique authorization, within the
   context of a particular NLS group.

5.1.  NLS SA TEK Policy

   The following describes how NLS policy is represented in the MAC SA
   TEK payload.

   o  MAC Algorithm.  This field maps to the Keyed Message Digest field
      of the RFC 2747 INTEGRITY Object.  Supported algorithms are: HMAC-
      SHA1-96.

   o  Anti-Replay.  The COUNTER type of anti-replay protection is
      supported.

   o  Key Lifetime.  NLS does not specify a validity period for policy.
      This field MUST be set to zero.

   o  SPI.  NLS does not specify a key identifier, but this field is
      used by GDOI to synchronize policy distributed in an MAC SA TEK
      and KD payloads.

   o  SPI Size.  The length of the SPI MUST be 4 octets.

5.2.  Application-specific attributes

   o  AGID (V).  This attribute specifies a single NLS AGID that is
      associated with this policy.  Multiple AGIDs attributes (each
      specifying a unique AGID) MAY be included in the SA TEK.

   o  Authz (V).  This attribute contains a token used for
      authorization.  The format and usage of this authorization token
      is outside of the scope of this memo.







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6.  Requirements for adding additional application support

   Any memo supporting the definitions in the memo MUST include the
   following information relating to the application:

   o  Define an Application Type mnemonic, and provide a reference to a
      document describing the protocol specification.

   o  Define a set of MAC algorithms.

   o  Define anti-replay types.

   o  Define key lifetime parameters.

   o  Define valid SPI values and lengths.

   o  Description of Optional Attributes.


































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7.  IANA Considerations

   A new GDOI SA TEK type Protocol-ID type [GDOI-REG] should be assigned
   from the Unassigned space.  The new algorithm id should be called
   GDOI_PROTO_MAC, and refers to the Message Authentication Code Policy
   SA TEK described in Section 3.1 of this memo.

   Terms describing policies for allocating new name space types below
   are defined in [RFC5226].

   The following applications are defined as part of this memo.

                Application   Type        Value
                 ------------------        -----
                 RESERVED                    0
                 RSVP                        1
                 NLS                         2
                 Specification Required     3-127
                 Private Use              128-255

   The following MAC Algorithms are defined as a part of this memo.

                 MAC Algorithm Type        Value
                 ------------------        -----
                 RESERVED                    0
                 HMAC-MD5                    1
                 HMAC-SHA1-96                2
                 Specification Required     3-127
                 Private Use              128-255

   The following Sequence Number Types are defined as a part of this
   memo.

                 Sequence Number Type        Value
                 --------------------        -----
                 RESERVED                      0
                 COUNTER                       1
                 TIME                          2
                 Specification Required       3-127
                 Private Use                128-255











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   The following Optional Attributes are defined as part of this memo,
   used with an Application of type RSVP.

                 RSVP Optional Attribute   Value
                 -----------------------   -----
                 RESERVED                    0
                 KeyStartValid               1
                 Specification Required     2-127
                 Private Use              128-255

   The following Optional Attributes are defined as part of this memo,
   used with an Application of type NLS.

                 NLS Optional Attribute   Value
                 ----------------------   -----
                 RESERVED                    0
                 AGID                        1
                 Authz                       2
                 Specification Required     3-127
                 Private Use              128-255































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8.  Security Considerations

   This memo describes the passing of policy and keying material used by
   two applications: an RSVP speaker producing an RFC 2747 INTEGRITY
   Object, and an NLS speaker producing A_RESPONSE, B_RESPONSE, and
   AUTHENTICATION TLVs.  This policy and keying material is protected by
   the GDOI protocol described in [I-D.ietf-msec-gdoi-update].  The
   security considerations in that memo apply fully to this memo as
   well.

   The use of the MAC SA TEK to distribute policy and keys is only
   appropriate when the application is using a group security model.
   [I-D.ietf-tsvwg-rsvp-security-groupkeying] describes the
   circumstances when a group security model may be used with RSVP.  NLS
   always uses a group security model.




































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9.  References

9.1.  Normative References

   [I-D.ietf-msec-gdoi-update]
              Weis, B., Rowles, S., and T. Hardjono, "The Group Domain
              of Interpretation", draft-ietf-msec-gdoi-update-11 (work
              in progress), August 2011.

9.2.  Informative References

   [GDOI-REG]
              Internet Assigned Numbers Authority, "Group Domain of
              Interpretation (GDOI) Payload Type Values", IANA Registry,
              December 2004,
              <http://www.iana.org/assignments/gdoi-payloads>.

   [I-D.ietf-tsvwg-rsvp-security-groupkeying]
              Behringer, M., Faucheur, F., and B. Weis, "Applicability
              of Keying Methods for RSVP Security",
              draft-ietf-tsvwg-rsvp-security-groupkeying-11 (work in
              progress), September 2011.

   [I-D.shore-nls-tl]
              Shore, M., McGrew, D., and K. Biswas, "Network-Layer
              Signaling: Transport Layer", draft-shore-nls-tl-06 (work
              in progress), July 2008.

   [RFC2104]  Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-
              Hashing for Message Authentication", RFC 2104,
              February 1997.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2408]  Maughan, D., Schneider, M., and M. Schertler, "Internet
              Security Association and Key Management Protocol
              (ISAKMP)", RFC 2408, November 1998.

   [RFC2747]  Baker, F., Lindell, B., and M. Talwar, "RSVP Cryptographic
              Authentication", RFC 2747, January 2000.

   [RFC3097]  Braden, R. and L. Zhang, "RSVP Cryptographic
              Authentication -- Updated Message Type Value", RFC 3097,
              April 2001.

   [RFC3740]  Hardjono, T. and B. Weis, "The Multicast Group Security
              Architecture", RFC 3740, March 2004.



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   [RFC4230]  Tschofenig, H. and R. Graveman, "RSVP Security
              Properties", RFC 4230, December 2005.

   [RFC4301]  Kent, S. and K. Seo, "Security Architecture for the
              Internet Protocol", RFC 4301, December 2005.

   [RFC4302]  Kent, S., "IP Authentication Header", RFC 4302,
              December 2005.

   [RFC4303]  Kent, S., "IP Encapsulating Security Payload (ESP)",
              RFC 4303, December 2005.

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 5226,
              May 2008.




































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Authors' Addresses

   Brian Weis
   Cisco Systems
   170 W. Tasman Drive
   San Jose, California  95134-1706
   USA

   Phone: +1-408-526-4796
   Email: bew@cisco.com


   Sheela Rowles
   Cisco Systems
   170 W. Tasman Drive
   San Jose, California  95134-1706
   USA

   Phone: +1-408-527-7677
   Email: srowles@cisco.com































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