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Versions: 00 draft-ietf-nfsv4-ipv6

Internet Engineering Task Force                             Alex RN, Ed.
Internet-Draft                                         Bhargo Sunil, Ed.
Intended status: Standards Track                          Dhawal Bhagwat
Expires: December 29, 2009                                  Dipankar Roy
                                                       Rishikesh Barooah
                                                           June 27, 2009

                    NFS operation over IPv4 and IPv6

Status of this Memo

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

   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on December 29, 2009.

Copyright Notice

   Copyright (c) 2009 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 in effect on the date of
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   Please review these documents carefully, as they describe your rights
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   This Internet-Draft provides the description of problem set faced by
   NFS and its various side band protocols when implemented over IPv6 in
   various deployment scenarios.  Solution to the various problems are
   also given in the draft and are sought for approval in the respective
   NFS and side band protocol versions.


   This "forward" section is an unnumbered section that is not included
   in the table of contents.  It is primarily used for the IESG to make
   comments about the document.  It can also be used for comments about
   the status of the document and sometimes is used for the RFC2119
   requirements language statement.

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in RFC 2119 [RFC2119].

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Table of Contents

   1.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
     2.1.  Various Deployment Scenarios . . . . . . . . . . . . . . .  4
   3.  Multi homing support . . . . . . . . . . . . . . . . . . . . .  5
   4.  RPCBIND  . . . . . . . . . . . . . . . . . . . . . . . . . . .  6
   5.  NLM and NSM  . . . . . . . . . . . . . . . . . . . . . . . . .  7
   6.  Client Identification  . . . . . . . . . . . . . . . . . . . .  9
   7.  Dual to single stack mode transition . . . . . . . . . . . . . 10
   8.  NFSv4 Callback Information . . . . . . . . . . . . . . . . . . 11
   9.  Reply cache tuples for NFSv4 . . . . . . . . . . . . . . . . . 12
   10. External Interfaces  . . . . . . . . . . . . . . . . . . . . . 12
   11. Other optimizations  . . . . . . . . . . . . . . . . . . . . . 13
     11.1. Address Persistence  . . . . . . . . . . . . . . . . . . . 13
     11.2. IP addresses as keys . . . . . . . . . . . . . . . . . . . 13
     11.3. NFSv4 Id Mapping . . . . . . . . . . . . . . . . . . . . . 13
   12. Consideration for running NFS along with NAT/ALG . . . . . . . 13
     12.1. Asymmetric Reachability  . . . . . . . . . . . . . . . . . 14
   13. Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 14
   14. IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 14
   15. Security Considerations  . . . . . . . . . . . . . . . . . . . 14
   16. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14
     16.1. Normative References . . . . . . . . . . . . . . . . . . . 14
     16.2. Informative References . . . . . . . . . . . . . . . . . . 15
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 16

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1.  Terminology

   ALG: Application Level Gateway.

   NFS-ALG: NFS Application Level Gateway.

   Host: Used to refer to the client or the server where the specific(s)
   of client or the server does not matter.

   IPv4: Internet Protocol Version 4.

   IPv6: Internet Protocol Version 6.

   NAT: Network Address Translator.

   NFS: Used to refer to Network File System irrespective of the

   NFSv2: Network File System Protocol Version 2.

   NFSv3: Network File System Protocol version 3.

   NFSv4: Network File System Protocol version 4.

   NFSv4.1: Network File System Protocol version 4.1.

   NLM: Network Lock Manager Protocol.

   NSM: Network Status Monitor Protocol.

   Operation: Refers to the NFS operation when its mode of request or
   response is inconsequential.

2.  Introduction

   NFS being a application layer protocol can operate over several
   network layer protocols.  This draft addresses problems associated
   with NFS operation over IPv4 and IPv6.  NFS follows the client server
   approach and does not restrict the network layer capability of the

2.1.  Various Deployment Scenarios

   The various deployment scenarios are as follows:

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   (a)  Client in IPv4 only network and Server being in IPv4 only
   (b)  Client in IPv6 only network and Server being in IPv6 only
   (c)  Client in IPv4 only network and Server being in IPv6 only
   (d)  Client in IPv6 only network and Server being in IPv4 only
   (e)  Client in IPv4 and IPv6 capable network and Server being in IPv4
        and IPv6 capable network

   In the above mentioned scenarios, types a) b) are called symmetric
   stack mode of operation.  Type c) and d) can be called as asymmetric
   stack mode .  Type a)-d) can be interchangeably be called as single
   stack mode.  Type e) can be interchangeably be called as dual stack

   In the case of asymmetric stack operation mode the client and server
   MUST use protocol translation at the network level and the
   application level.  This is achieved using a combination of network
   level and application level protocol address translations done using
   NAT-PT and NFS-ALG.

   The problems which are discussed below are primarily related to state
   sharing across different protocol address families.  The states are
   maintained through NFSv4(or later versions) and NLM/NSM.

3.  Multi homing support

   IPv6 supports various types of scoped addresses which can be
   ambiguous at the scope boundary as referenced in [RFC4007] .  A link
   local address is one whose validity is only within a link and hence
   is link scoped.  Global addresses on the other hand are valid across

   In IPv6 case we can have link local address in a link scope boundary
   like say Host H1 having 2 interfaces connected to Clients C1,C2 on
   two links L1 and L2 as below.

                         Typical multi homed host

   C1---<L1>---- H1-------<L2>----C2

                                 Figure 1

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   The link local address is ambiguous because of the private nature
   Link L1 and L2 could have the same address (similar to private
   addresses of 10.x , 192.x in IPv4.  In IPv4 this is an exception but
   for IPv6 this is default, due to auto configuration).  In the case of
   outbound packet transmission the link scope could be ambiguous and
   MUST be explicitly specified or the implementation MAY support a
   default scoped addresses.

   NFS as a service operating in the link scope boundary MAY need to
   explicitly specify its scope of communication using a scope
   identifier [RFC4007], depending on different client scenarios
   supported.  NFS over IPv6 using link local address MAY be supported.
   In particular, the NFS server or client may or may not decide to
   support the scope field in an IPv6 link local address.

   NFS servers on scope boundaries doing an outbound communication, the
   scope SHOULD be derived from the inbound context when the server
   receives an NFSv4.0 SETCLIENTID operation or an RPCBIND GETVERSADDR
   procedure which contain universal addresses section 2.2 [RFC3530] .
   Any outbound communication initiated like NFSv4 callbacks or NSM
   notifies SHOULD use this information.

   For scenarios like NFS servers running over IPv6 with only auto-
   configured (link local only)addresses, some clients could boot off
   the NFS servers.  In such situations link local support SHOULD be
   supported.The NFS server MAY provide for a default scope to operate


   NFS servers supporting IPv6 MUST support RPCBINDv3 as defined in
   [RFC1833], over IPv6.  Additionally, RPCBINDv4 SHOULD be supported,
   as noted later in this section.

   RPCBINDv3/4 protocols 'use a transport-independent format for the
   transport address'.  Using RPCBINDv3/4, a client can clearly
   communicate to the server which transport (IPv4/v6, TCP/UDP) it is
   interested in for contacting a service.The server can communicate
   clearly to the client, the various transports on which a service is
   available.  RPCBINDv2 (aka PORTMAP) provides limited support in this

   RPCBINDv4 SHOULD be supported because it introduces useful procedures
   like, RPCBPROC_GETVERSADDR - to query the server for the address of a
   specific version of an RPC service and RPCBPROC_GETADDRLIST - to
   query the server for a list of all addresses / transports on which an
   RPC service is available.

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   Supporting RPCBINDv3/4 over IPv4 is OPTIONAL, if supported it may
   ease basic troubleshooting of IPv6 servers from IPv4 hosts.  It may
   also make it easier for applications to identify a transport of
   interest, that the server supports, by making RPCBPROC_GETADDRLIST
   calls over IPv4.

   The netid and address formats in the RPCBINDv3/4 procedures, MUST be
   as per those defined for netid and universal addresses, in netid_ID
   draft [netid_ID].  The implementation SHOULD NOT use IPv4 embedded
   IPv6 addresses defined in Section 2.5.5 [RFC4291], for the
   RPCBINDv3/4 procedures.

   Where specific information regarding a service is needed from a
   server, a client SHOULD prefer the RPCBINDv4 procedure
   scenarios where a list of details is required, a client SHOULD use
   the procedures RPCBPROC_DUMP and RPCBPROC_GETADDRLIST, as applicable.

   An NFS implementation SHOULD NOT propagate the link local addresses
   encoded as universal addresses from one link scope domain to another.
   This could result in the following problem

   a) Server has 2 different link local addresses, A1 and A2 on links L1
   and L2 .

   b) Client is in link L1.

   c) Server publishes RPCBIND universal address of link local address
   A1 and A2.

   d) Client decided to connect using A2.

   Step d) violates the usage of a link local private address as A2
   could be assigned to a valid host in the link scope of L1.

5.  NLM and NSM

   A dual stack NSM server implementation with persistent recording of
   source IP address SHOULD record at least one IPv4 and one IPv6
   address, for sending out NOTIFY messages.

   This will be required in the following scenario :

   a) Client connects to the server using IPv6 address.

   b) Client connects to the server using IPv4 address.

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   c) The server switches from dual stack to single stack mode of

   d) Server restarts.

   Step c) can happen due to a network or interface disruption.  Step c)
   can also happen after step d) which results in loss of ability of a
   host to contact the other host on a particular address family after

   The server in this case SHOULD associate two client addresses with
   the client identifier "caller_name" field as referenced in section
   6.1.4 [RFC1833] .

   After d) if the server does not record at least one address of each
   address family, the server after restarting will not be able to send
   NOTIFY to the client on the address family that faced disruption.
   This will result in the client incorrectly assuming that the server
   is holding locks when it is not, if the client expects the NOTIFY to
   come on the same interface and same version of the IP protocol on
   which the locks were requested.  The client when it receives the
   NOTIFY from the server holding locks, through one of the address
   families SHOULD try to reclaim the locks it had established on the
   other address family as well, if it can find out that both the
   addresses or address families refer to the same server.

   Another example is, the client after establishing the locks on the
   server on both the address families, restarts.  When the client comes
   back up and if the server can not be contacted on one of the address
   families, it SHOULD use the "caller_name" in the name field of the
   NOTIFY so that server when it receives the NOTIFY should be able to
   remove the locks the client had held on other address family as well.

   The server SHOULD identify the client based on the "caller_name"
   field in the NLM request and it SHOULD remain constant irrespective
   of the address family that the client uses to contact the server.
   This would help the server in identifying which client's lock to
   release in the event the client sends the notify from a different
   address family than the one on which it had sent the NLM operations.
   This would also help in the case, when the mode of operation is
   asymmetric stack and the intermediate NAT-PT changes source address
   while connecting to the server.

   Callback port information verification from server to client for IPv6
   cases MUST be done through RPCBIND.  The scenarios are asynchronous
   lock requests and call back port verification during granting of
   waiting locks.

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6.  Client Identification

   In the case of NFS4.1 the short hand clientid is very similar to
   NFSv4.0 clientid.  Since states are tied to clientid, state sharing
   across and within sessions are immune to individual connection
   failures.  The failures from individual connections of an address
   family can be failed over to another address family if available.

   As per current NFSv4.0 standards RFC3530 [RFC3530] server identifies
   the client using the short identifier called as Client Identifier.
   Client MUST send a different client string in SETCLIENTID to a
   different destination addresses(s)/family of address(s).  Even if the
   same server is servicing on a different network address/address
   family the server MUST return a different clientid to the client.
   This is to prevent confusion on the client side as there is no way of
   determining whether the server to which the client is connecting
   again is the same or not.

   The usage of different client strings for different network addresses
   families might result in a case that the request(s) from the same
   client be deemed to conflict and will result in revocation of
   delegation.  This can happen in the given client scenario:

   a) Client establishes a connection to server on address X with
   address family IPv4 and then opens the file Z in write mode.

   b) Server grants the client will get a write delegation.

   c)Client breaks the connection with server address X and/or tries to
   establish another connection with server address Y with address
   family B and then tries to open the file Z.

   In step c) as client is trying to connect to a different server
   address/address famiily it would send the SETCLIENTID with different
   client string than in step a).  As the clientid given in step c) will
   be different than the clientid granted in step a) the server will end
   up revoking the delegation granted in step b).  This is because the
   clientid is calculated based on client string which would be
   different in step a) and step c).  Step c) can happen even if the
   client side faced a disruption on one of its address families and
   then connected on a different address family to the server.  Example
   would be client connected using IPv4 in step a) and then client IPv4
   stack or interfaces faced disruption after step b).  Client then uses
   the IPv6 to connect to server in step c).  In either case after step
   c) the client would not be holding the delegation.

   To handle this case the server SHOULD NOT use the client string alone
   in the generation of the short hand clientid but should combine the

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   client string with its own server identifier to calculate the
   clientid.  The server identifier should be generated in a unique way
   on similar lines as that of the client identifier.  Specifically the
   server identifier should be such that no two servers should use the
   same server identifier.  An example of well generated server
   identifier can be the one that includes the following :

   a) MAC address

   b) Machine serial number

   The client SHOULD always send the SETCLIENTID as the first request on
   the connection.  Even if the client is retransmitting the request on
   a new connection it SHOULD send the SETCLIENTID as the first request.
   The client SHOULD use the same client string across different IP
   address families as no two different servers would end up giving the
   same clientid as both the components, client string and server
   identifier, used in the calculation are unique.  If the clientid
   returned by server is the same as one of the existing clientid, the
   client SHOULD conclude that both the connections are to the same
   server.  To prevent the server from expunging the client due to non
   renewal, the client should send a RENEW even if it does not have a
   lease after a SETCLIENTID to the server.

   In the above example the client string in step c) would have been the
   same as step a) and therefore the server would not revoke the
   delegation granted in step b).

7.  Dual to single stack mode transition

   Dual stack implementations of NFS over IPv4 and IPv6 should ensure
   that the shutdown of one stack implementation leaves the host in a
   usable state.  This is important for shared state like locks
   accessible through both IPv4 and IPv6 paths.  A shutdown of one path
   would result in a permanent, partial, or temporary un-reachability to
   the client.  Anticipating reconnects, after the partial reachability
   condition are resolved, the states should be left intact.
   Administrative support for forceful lock management (removal /cleanup
   etc) is recommended.

   Shutting down of one stack IPv4/IPv6 or loss of all interfaces of one
   particular address family IPv4/IPv6 should not result in the NFSv4.0
   client states to be removed after the lease period expires.  This is
   required so that server does not grant the locks to any other client
   reachable from another address family.  If the locks are removed the
   subsequent clients over IPv4, which are granted locks might find the
   the file to be in unusable state.

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   a) If the IPv6 client A is connected to the server and has locks and
   open share state.

   b) The partial reachability condition happens for IPv6.

   c) The IPv4 client B tries to access the files on which the client A
   had states.

   If after step b) the server had removed the state then the client B
   might find the file to be in unusable state and so the state for
   client A should be maintained unless the disruption due to step b) is
   permanent, in which case the administrator needs to take some steps
   to prevent the unusable file state.

   For NFSv4 one of the ways to implement the above recommendation is
   that the server should mark the client and the states associated with
   it as temporarily unusable but should not remove the state associated
   with the clients in such case.  After the complete reachability is
   restored the server should go into partial restart case for only the
   clients that had their state marked as temporarily unusable and thus
   should allow such clients to regain their state.  The server should
   identify the clientid/states that are marked as temporarily unusable
   will start the state recovery procedure on the client side.  The
   server can remove the client state if the clients have not recovered
   the state in the grace period after the complete reachability
   condition has been restored.

   Supposedly the partial reachability condition affected only the
   clients accessing the server over IPv6, after the reachability is
   restored then the grace period should be started for only the clients
   coming over IPv6.  If the clients are coming over IPv4 contending for
   the same lock for which is being held by IPv6 client the IPv4 client
   should be denied.

   For the case of NLM in such cases the NOTIFY should be sent to
   clients that were affected due to partial reachability condition and
   that had held the locks prior to that condition coming into effect.

8.  NFSv4 Callback Information

   In the case of asymmetric stack mode, if the client is in IPv6
   network and tries to contact the server in IPv4 domain it should be
   using an IPv6 address transparently translated by an ALG.  The
   intermediate network element (NFS-ALG) in the asymmetric stack mode
   should convert the embedded addresses in the NFS operations so that
   the other host can understand the network address.

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   The NFSv4 server implementation should verify the netid information
   in the callbacks corresponds to respective address families.  The
   netid used for IPv6 address is tcp6 and for IPv4 addresses is tcp.

9.  Reply cache tuples for NFSv4

   Currently, most of the reply cache implementations use some form of
   combination of the elements client address, client port, server
   address, protocol, RPC XID as the values on which to decide on the
   hit in the cache.  But if the environment is such that the client is
   working only in one address family and the server in another family
   (no dual stack) and the translation is handled by an intermediate
   element, then it might be possible that when the client retransmits
   the request the source pair (address/port) that the server sees might
   change from the previous connection values and the replay cache might
   be rendered ineffective.  It might also be that the client has lost
   all of its interfaces of a particular address family and might switch
   to another address family.  It might also be the case that the client
   uses a new source pair for the retransmission which will have the
   similar effect.

   As listed in Client Identification (Section 6) the client can obviate
   the need to send different client strings to different server
   addresses.  The NFSv4.0 client should always send the SETCLIENTID
   procedure as the first request to the server.  If a request is to be
   retransmitted on a different connection, the first procedure sent out
   should be a SETCLIENTID with no change in the callback address or
   client string or verifier.  This will help the server to associate
   the new connection with the clientid.

   The replay cache implementations thus can switch to just using the
   client string and RPC XID as the basis for determining a replay cache
   hit, if the server is using the address/address family to determine
   the cache hit.

10.  External Interfaces

   NFS servers considering usage of information like MTU control or
   other lower level information from the IPv6 stack MAY consider, the
   updated standard sockets APIs in the form of advanced sockets
   implementation as specified in RFC 3542 [RFC3542] and RFC 3493

   In the case of client and server operating in different address
   families with no dual stack support DNS-ALG and NAT-PT MUST be used.

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11.  Other optimizations

11.1.  Address Persistence

   In all cases where the IP addresses are stored in stable storage it
   is always preferable to store addresses with the address family
   information.  The scenarios could be that of recording addresses for
   NSM notifies and client addresses persistently stored for reply
   cache.  One way of implicit typing is with the IPv4 mapped IPv6
   addresses for storage efficiency.  It is RECOMMENDED that IPv6
   support capability information is preserved.  This information can be
   used during upgrades and downgrades of NFS server instances which
   have may or may not have turned on support for NFS over IPv6.

11.2.  IP addresses as keys

   There are a number of situations where decisions are based on the IP
   addresses like access control, which determines which IP address gets
   access and which does not.  Other situations like distributing
   resources based on the client IP addresses within an implementation
   system, the resources could be the amount of cached replies.

   When considering using IP addresses as keys into these scenarios, the
   variability of the bits in the IP addresses SHOULD be considered.  In
   IPv6 for the same interface the different address differ mostly in
   the non subnet part, in IPv4 that is not the case.  The lower order
   bits are generated from the MAC addresses and are mostly static.

11.3.  NFSv4 Id Mapping

   The "dns_domain" in "user@dns_domain" as referred in section 5.8
   [RFC3530], used to map owners, groups, users and user groups in the
   string principals to internal representations at the client and
   server SHOULD be the same for the same client accessing an NFSv4
   server simultaneously over IPv4 and IPv6.

12.  Consideration for running NFS along with NAT/ALG

   For NFS ALGs, the only information at the protocol level is the
   embedded universal addresses, which SHOULD be translated for RPCBIND
   and SETCLIENTID calls to work transparently.  If names are used as
   identifiers then DNS-ALG should be used for translating names.  The
   ALG SHOULD NOT multiplex multiple client side connections to single
   server side connection.

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12.1.  Asymmetric Reachability

   If the server is in IPv6/IPv4 address space and the client is in
   IPv4/IPv6 address space connected through intermediate translation
   network element, then a separate callback port can be fixed.

13.  Acknowledgments

   The authors would like to acknowledge Mike Eisler for reviews of the
   various early versions of the draft.

14.  IANA Considerations

   This memo includes no request to IANA.

15.  Security Considerations

   All considerations from RFC 3530 Section 16 [RFC3530]

16.  References

16.1.  Normative References

   [RFC1813]  Callaghan, B., Pawlowski, B., and P. Staubach, "NFS
              Version 3 Protocol Specification", RFC 1813, June 1995.

   [RFC1833]  Srinivasan, R., "Binding Protocols for ONC RPC Version 2",
              RFC 1833, August 1995.

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

   [RFC2460]  Deering, S. and R. Hinden, "Internet Protocol, Version 6
              (IPv6) Specification", RFC 2460, December 1998.

   [RFC3530]  Shepler, S., Callaghan, B., Robinson, D., Thurlow, R.,
              Beame, C., Eisler, M., and D. Noveck, "Network File System
              (NFS) version 4 Protocol", RFC 3530, April 2003.

   [RFC4007]  Deering, S., Haberman, B., Jinmei, T., Nordmark, E., and
              B. Zill, "IPv6 Scoped Address Architecture", RFC 4007,
              March 2005.

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   [RFC4291]  Hinden, R. and S. Deering, "IP Version 6 Addressing
              Architecture", RFC 4291, February 2006.

   [RFC4506]  Eisler, M., "XDR: External Data Representation Standard",
              STD 67, RFC 4506, May 2006.

   [RFC5378]  Bradner, S. and J. Contreras, "Rights Contributors Provide
              to the IETF Trust", BCP 78, RFC 5378, November 2008.

   [RFC5531]  Thurlow, R., "RPC: Remote Procedure Call Protocol
              Specification Version 2", RFC 5531, May 2009.

              Eisler, M., "IANA Considerations for RPC Net Identifiers
              and Universal Address Formats",
              draft-ietf-nfsv4-rpc-netid-04 (work in progress),
              December 2008.

16.2.  Informative References

   [RFC1094]  Nowicki, B., "NFS: Network File System Protocol
              specification", RFC 1094, March 1989.

   [RFC2624]  Shepler, S., "NFS Version 4 Design Considerations",
              RFC 2624, June 1999.

   [RFC2663]  Srisuresh, P. and M. Holdrege, "IP Network Address
              Translator (NAT) Terminology and Considerations",
              RFC 2663, August 1999.

   [RFC3493]  Gilligan, R., Thomson, S., Bound, J., McCann, J., and W.
              Stevens, "Basic Socket Interface Extensions for IPv6",
              RFC 3493, February 2003.

   [RFC3542]  Stevens, W., Thomas, M., Nordmark, E., and T. Jinmei,
              "Advanced Sockets Application Program Interface (API) for
              IPv6", RFC 3542, May 2003.

   [RFC3593]  Tesink, K., "Textual Conventions for MIB Modules Using
              Performance History Based on 15 Minute Intervals",
              RFC 3593, September 2003.

   [RFC4620]  Crawford, M. and B. Haberman, "IPv6 Node Information
              Queries", RFC 4620, August 2006.

   [RFC5234]  Crocker, D. and P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", STD 68, RFC 5234, January 2008.

Alex RN, et al.         Expires December 29, 2009              [Page 15]

Internet-Draft           draft-alexrn-nfsv4-ipv6               June 2009

Authors' Addresses

   Alex RN (editor)
   3rd Floor, Fair Winds Block, EGL Software Park,
   Bangalore, Karnataka  560071

   Phone: +91-80-41843352
   Email: rnalex@netapp.com

   Bhargo Sunil (editor)
   3rd Floor, Fair Winds Block, EGL Software Park,
   Bangalore, Karnataka  560071

   Phone: +91-80-41843963
   Email: bhargo@netapp.com

   Dhawal Bhagwat
   3rd Floor, Fair Winds Block, EGL Software Park,
   Bangalore, Karnataka  560071

   Phone: +91-80-41843134
   Email: dhawal@netapp.com

   Dipankar Roy

   Phone: +91-80-41843303
   Email: dipankar@netapp.com

   Rishikesh Barooah

   Email: rbarooah@netapp.com

Alex RN, et al.         Expires December 29, 2009              [Page 16]

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