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Behave                                                      S. Sivakumar
Internet-Draft                                                  R. Penno
Intended status: Standards Track                           Cisco Systems
Expires: July 18, 2013                                  January 14, 2013


           IPFIX Information Elements for logging NAT Events
                 draft-sivakumar-behave-nat-logging-06

Abstract

   NAT devices are required to log events like creation and deletion of
   translations and information about the resources it is managing.
   With the wide deployment of Carrier Grade NAT (CGN) devices, the
   logging of events have become very important for legal purposes.  The
   logs are required in many cases to identify an attacker or a host
   that was used to launch malicious attacks and/or for various other
   purposes of accounting.  Since there is no standard way of logging
   this information, different NAT devices behave differently and hence
   it is difficult to expect a consistent behavior.  The lack of a
   consistent way makes it difficult to write the collector applications
   that would receive this data and process it to present useful
   information.  This document describes the information that is
   required to be logged by the NAT devices.

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 July 18, 2013.

Copyright Notice

   Copyright (c) 2013 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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   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.


Table of Contents

   1.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
     2.1.  Requirements Language  . . . . . . . . . . . . . . . . . .  3
   3.  Scope  . . . . . . . . . . . . . . . . . . . . . . . . . . . .  3
   4.  Event based logging  . . . . . . . . . . . . . . . . . . . . .  4
     4.1.  Information Elements . . . . . . . . . . . . . . . . . . .  4
     4.2.  Definition of NAT Events . . . . . . . . . . . . . . . . .  7
     4.3.  Quota exceeded - Sub Event types . . . . . . . . . . . . .  8
     4.4.  Templates for NAT Events . . . . . . . . . . . . . . . . .  8
       4.4.1.  NAT44 create and delete session event  . . . . . . . .  8
       4.4.2.  NAT64 create and delete session event  . . . . . . . .  9
       4.4.3.  NAT44 BIB create and delete event  . . . . . . . . . . 10
       4.4.4.  NAT64 BIB create and delete event  . . . . . . . . . . 10
       4.4.5.  Addresses Exhausted event  . . . . . . . . . . . . . . 10
       4.4.6.  Ports Exhausted event  . . . . . . . . . . . . . . . . 11
       4.4.7.  Quota exceeded . . . . . . . . . . . . . . . . . . . . 11
       4.4.8.  Address Binding  . . . . . . . . . . . . . . . . . . . 12
       4.4.9.  Port block allocation and de-allocation  . . . . . . . 12
   5.  Encoding . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
     5.1.  IPFIX  . . . . . . . . . . . . . . . . . . . . . . . . . . 13
   6.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 13
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 13
   8.  Security Considerations  . . . . . . . . . . . . . . . . . . . 13
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
     9.1.  Normative References . . . . . . . . . . . . . . . . . . . 13
     9.2.  Informative References . . . . . . . . . . . . . . . . . . 14
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14












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1.  Terminology

   The usage of the term "NAT device" in this document refer to any
   NAT44 and NAT64 devices.  The usage of the term "collector" refers to
   any device that receives the binary data from a NAT device and
   converts that into meaningful information.  This document uses the
   term "Session" as it is defined in [RFC2663] and the term BIB as it
   is defined in [RFC6146]


2.  Introduction

   This document details the IPFIX Information Elements(IEs) that are
   required for logging by a NAT device.  The document will specify the
   format of the IE's that are required to be logged by the NAT device
   and all the optional fields.  The fields specified in this document
   are gleaned from [RFC4787] and [RFC5382].

2.1.  Requirements Language

   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].


3.  Scope

   This document provides the information model to be used for logging
   the NAT devices including Carrier Grade NAT (CGN) events.  This
   document focuses exclusively on the specification of IPFIX IE's.
   This document does not provide guidance on the transport protocol
   like TCP, UDP or SCTP that is to be used to log NAT events.  The log
   events SHOULD NOT be lost but the choice of the actual transport
   protocol is beyond the scope of this document.

   The existing IANA IPFIX Information Elements registry [IPFIX-IANA]
   already has assignments for many NAT logging events.  For
   convenience, this document uses those same Information Elements.
   However, as stated earlier, this document is not defining IPFIX or
   Netflow 9 as the framework for logging.  Rather, the information
   contained in these elements is within the scope of this document.

   This document assumes that the NAT device will use the existing IPFIX
   framework to send the log events to the collector.  This would mean
   that the NAT device will specify the template that it is going to use
   for each of the events.  The templates can be of varying length and
   there could be multiple templates that a NAT device could use to log
   the events.



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   The implementation details of the collector application is beyond the
   scope of this document.

   The optimization of logging the NAT events are left to the
   implementation and are beyond the scope of this document.


4.  Event based logging

   An event in a NAT device can be viewed as a happening as it relates
   to the management of NAT resources.  The creation and deletion of NAT
   sessions and bindings are examples of events as it results in the
   resources (addresses and ports) being allocated or freed.  The events
   can happen either through the processing of data packets flowing
   through the NAT device or through an external entity installing
   policies on the NAT router or as a result of an asynchronous event
   like a timer.  The list of events are provided in Section 4.1.  Each
   of these events SHOULD be logged, unless they are administratively
   prohibited.  A NAT device MAY log these events to multiple collectors
   if redundancy is required.  The network administrator will specify
   the collectors to which the log records are to be sent.

   A collector may receive NAT events from multiple CGN devices and
   should be able to distinguish between the devices.  Each CGN device
   should have a unique source ID to identify themselves.  The source ID
   is part of the IPFIX template and data exchange.

   Prior to logging any events, the NAT device MUST send the template of
   the record to the collector to advertise the format of the data
   record that it is using to send the events.  The templates can be
   exchanged as frequently as required given the reliability of the
   connection.  There SHOULD be a configurable timer for controlling the
   template refresh.  NAT device SHOULD combine as many events as
   possible in a single packet to effectively utilize the network
   bandwidth.

4.1.  Information Elements

   The templates could contain a subset of the Information Elements(IEs)
   shown in Table 1 depending upon the event being logged.  For example
   a NAT44 session creation template record will contain,

   {sourceIPv4Adress, postNATSourceIPv4Address, destinationIpv4Address,
   postNATDestinationIPv4Address, sourceTransportPort,
   postNAPTSourceTransportPort, destinationTransportPort,
   postNAPTDestTransportPort, natOriginatingAddressRealm, natEvent,
   timeStamp}




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   An example of the actual event data record is shown below - in a
   readable form

   {192.168.16.1, 201.1.1.100, 207.85.231.104, 207.85.231.104, 14800,
   1024, 80, 80, 0, 1, 09:20:10:789}

   A single NAT device could be exporting multiple templates and the
   collector should support receiving multiple templates from the same
   source.










































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   The following is the table of all the IE's that a CGN device would
   need to export the events.  The formats of the IE's and the IPFIX IDs
   are listed below.

   +----------------------------------+--------+-------+---------------+
   |            Field Name            |  Size  |  IANA |  Description  |
   |                                  | (bits) | IPFIX |               |
   |                                  |        |   ID  |               |
   +----------------------------------+--------+-------+---------------+
   |             timeStamp            |   64   |  323  |  System Time  |
   |                                  |        |       |    when the   |
   |                                  |        |       |     event     |
   |                                  |        |       |    occured.   |
   |              vlanID              |   16   |   58  |   VLAN ID in  |
   |                                  |        |       |    case of    |
   |                                  |        |       |  overlapping  |
   |                                  |        |       |    networks   |
   |           ingressVRFID           |   32   |  234  |   VRF ID in   |
   |                                  |        |       |    case of    |
   |                                  |        |       |  overlapping  |
   |                                  |        |       |    networks   |
   |         sourceIPv4Address        |   32   |   8   |  Source IPv4  |
   |                                  |        |       |    Address    |
   |     postNATSourceIPv4Address     |   32   |  225  |   Translated  |
   |                                  |        |       |  Source IPv4  |
   |                                  |        |       |    Address    |
   |        protocolIdentifier        |    8   |   4   |   Transport   |
   |                                  |        |       |    protocol   |
   |        sourceTransportPort       |   16   |   7   |  Source Port  |
   |    postNAPTsourceTransportPort   |   16   |  227  |   Translated  |
   |                                  |        |       |  Source port  |
   |      destinationIPv4Address      |   32   |   12  |  Destination  |
   |                                  |        |       |  IPv4 Address |
   |   postNATDestinationIPv4Address  |   32   |  226  |   Translated  |
   |                                  |        |       |      IPv4     |
   |                                  |        |       |  destination  |
   |                                  |        |       |    address    |
   |     destinationTransportPort     |   16   |   11  |  Destination  |
   |                                  |        |       |      port     |
   | postNAPTdestinationTransportPort |   16   |  228  |   Translated  |
   |                                  |        |       |  Destination  |
   |                                  |        |       |      port     |
   |         sourceIPv6Address        |   27   |  128  |  Source IPv6  |
   |                                  |        |       |    address    |
   |      destinationIPv6Address      |   128  |   28  |  Destination  |
   |                                  |        |       |  IPv6 address |





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   |     postNATSourceIPv6Address     |   128  |  281  |   Translated  |
   |                                  |        |       |  source IPv6  |
   |                                  |        |       |    addresss   |
   |   postNATDestinationIPv6Address  |   128  |  282  |   Translated  |
   |                                  |        |       |  Destination  |
   |                                  |        |       |  IPv6 address |
   |    natOriginatingAddressRealm    |    8   |  229  | Address Realm |
   |             natEvent             |    8   |  230  | Type of Event |
   |          portRangeStart          |   16   |  361  |   Allocated   |
   |                                  |        |       |   port block  |
   |                                  |        |       |     start     |
   |           portRangeEnd           |   16   |  362  |   Allocated   |
   |                                  |        |       |   Port block  |
   |                                  |        |       |      end      |
   |         portRangeStepSize        |   16   |  363  |  Step size of |
   |                                  |        |       |   next port   |
   |         portRangeNumPorts        |   16   |  364  |   Number of   |
   |                                  |        |       |     ports     |
   +----------------------------------+--------+-------+---------------+

                      Table 1: Template format Table

4.2.  Definition of NAT Events

   The following are the list of NAT events and the proposed event
   values.  The list can be expanded in the future as necessary.  The
   data record will have the corresponding natEvent value to identify
   the event that is being logged.

                   +--------------------------+--------+
                   |        Event Name        | Values |
                   +--------------------------+--------+
                   |   NAT44 Session create   |    1   |
                   |   NAT44 Session delete   |    2   |
                   |  NAT Addresses exhausted |    3   |
                   |   NAT64 Session create   |    4   |
                   |   NAT64 Session delete   |    5   |
                   |     NAT44 BIB create     |    6   |
                   |     NAT44 BIB delete     |    7   |
                   |     NAT64 BIB create     |    8   |
                   |     NAT64 BIB delete     |    9   |
                   |    NAT ports exhausted   |   10   |
                   |      Quota exceeded      |   11   |
                   |      Address Binding     |   12   |
                   |   Port block allocation  |   13   |
                   | Port block de-allocation |   14   |
                   +--------------------------+--------+




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                        Table 2: NAT Event ID table

4.3.  Quota exceeded - Sub Event types

   The following table shows the sub event types for the Quota exceeded
   event

                  +---------------------------+--------+
                  | Quota Exceeded Event Name | Values |
                  +---------------------------+--------+
                  |    Max Session entries    |    1   |
                  |      Max BIB entries      |    2   |
                  |    Max entries per user   |    3   |
                  +---------------------------+--------+

                        Table 3: Sub Event ID table

4.4.  Templates for NAT Events

   The following is the template of events that will have to logged.
   The events below are identified at the time of this writing but the
   events are expandable.  Depending on the implementation and
   configuration various IE's specified can be included or ignored.

4.4.1.  NAT44 create and delete session event

   This event will be generated when a NAT44 session is created or
   deleted.  The template will be the same, the natEvent will indicate
   whether it is a create or a delete event.  The following is a
   template of the event.





















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      +----------------------------------+-------------+-----------+
      |            Field Name            | Size (bits) | Mandatory |
      +----------------------------------+-------------+-----------+
      |             timeStamp            |      64     |    Yes    |
      |        vlanID/ingressVRFID       |      32     |     No    |
      |         sourceIPv4Address        |      32     |    Yes    |
      |     postNATSourceIPv4Address     |      32     |    Yes    |
      |        protocolIdentifier        |      8      |    Yes    |
      |        sourceTransportPort       |      16     |    Yes    |
      |    postNAPTsourceTransportPort   |      16     |    Yes    |
      |      destinationIPv4Address      |      32     |     No    |
      |   postNATDestinationIPv4Address  |      32     |     No    |
      |     destinationTransportPort     |      16     |     No    |
      | postNAPTdestinationTransportPort |      16     |     No    |
      |    natOriginatingAddressRealm    |      8      |     No    |
      |             natEvent             |      8      |    Yes    |
      +----------------------------------+-------------+-----------+

               Table 4: NAT44 Session delete/create template

4.4.2.  NAT64 create and delete session event

   This event will be generated when a NAT64 session is created.  The
   following is a template of the event.

      +----------------------------------+-------------+-----------+
      |            Field Name            | Size (bits) | Mandatory |
      +----------------------------------+-------------+-----------+
      |             timeStamp            |      64     |    Yes    |
      |        vlanID/ingressVRFID       |      32     |     No    |
      |         sourceIPv6Address        |     128     |    Yes    |
      |     postNATSourceIPv4Address     |      32     |    Yes    |
      |        protocolIdentifier        |      8      |    Yes    |
      |        sourceTransportPort       |      16     |    Yes    |
      |    postNAPTsourceTransportPort   |      16     |    Yes    |
      |      destinationIPv6Address      |     128     |     No    |
      |   postNATDestinationIPv4Address  |      32     |     No    |
      |     destinationTransportPort     |      16     |     No    |
      | postNAPTdestinationTransportPort |      16     |     No    |
      |    natOriginatingAddressRealm    |      8      |     No    |
      |             natEvent             |      8      |    Yes    |
      +----------------------------------+-------------+-----------+

            Table 5: NAT64 session create/delete event template







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4.4.3.  NAT44 BIB create and delete event

   This event will be generated when a NAT44 Bind entry is created.  The
   following is a template of the event.

         +-----------------------------+-------------+-----------+
         |          Field Name         | Size (bits) | Mandatory |
         +-----------------------------+-------------+-----------+
         |          timeStamp          |      64     |    Yes    |
         |     vlanID/ingressVRFID     |      32     |     No    |
         |      sourceIPv4Address      |      32     |    Yes    |
         |   postNATSourceIPv4Address  |      32     |    Yes    |
         |      protocolIdentifier     |      8      |     No    |
         |     sourceTransportPort     |      16     |     No    |
         | postNAPTsourceTransportPort |      16     |     No    |
         |  natOriginatingAddressRealm |      8      |     No    |
         |           natEvent          |      8      |    Yes    |
         +-----------------------------+-------------+-----------+

              Table 6: NAT44 BIB create/delete event template

4.4.4.  NAT64 BIB create and delete event

   This event will be generated when a NAT64 Bind entry is created.  The
   following is a template of the event.

         +-----------------------------+-------------+-----------+
         |          Field Name         | Size (bits) | Mandatory |
         +-----------------------------+-------------+-----------+
         |          timeStamp          |      64     |    Yes    |
         |     vlanID/ingressVRFID     |      32     |     No    |
         |      sourceIPv6Address      |     128     |    Yes    |
         |   postNATSourceIPv4Address  |      32     |    Yes    |
         |      protocolIdentifier     |      8      |     No    |
         |     sourceTransportPort     |      16     |     No    |
         | postNAPTsourceTransportPort |      16     |     No    |
         |  natOriginatingAddressRealm |      8      |     No    |
         |           natEvent          |      8      |    Yes    |
         +-----------------------------+-------------+-----------+

              Table 7: NAT64 BIB create/delete event template

4.4.5.  Addresses Exhausted event

   This event will be generated when a NAT device runs out of global
   IPv4 addresses in a given pool of addresses.  Typically, this event
   would mean that the NAT device wont be able to create any new
   translations until some addresses/ports are freed.  The following is



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   a template of the event.

                 +-------------+-------------+-----------+
                 |  Field Name | Size (bits) | Mandatory |
                 +-------------+-------------+-----------+
                 |  timeStamp  |      64     |    Yes    |
                 |   natEvent  |      8      |    Yes    |
                 | natPoolName |    String   |    Yes    |
                 +-------------+-------------+-----------+

               Table 8: NAT Address Exhausted event template

4.4.6.  Ports Exhausted event

   This event will be generated when a NAT device runs out of ports for
   a global IPv4 address.  Port exhaustion shall be reported per
   protocol (UDP, TCP etc) The following is a template of the event.

          +--------------------------+-------------+-----------+
          |        Field Name        | Size (bits) | Mandatory |
          +--------------------------+-------------+-----------+
          |         timeStamp        |      64     |    Yes    |
          |         natEvent         |      8      |    Yes    |
          | postNATSourceIPv4Address |      32     |    Yes    |
          |    protocolIdentifier    |      8      |    Yes    |
          +--------------------------+-------------+-----------+

                Table 9: NAT Ports Exhausted event template

4.4.7.  Quota exceeded

   This event will be generated when a NAT device cannot allocate
   resources as a result of an administratively defined policy.  The
   examples of Quota exceeded are to allow only certain number of NAT
   sessions per device, certain number of NAT sessions per user etc.
   The following is a template of the event.

             +--------------------+-------------+-----------+
             |     Field Name     | Size (bits) | Mandatory |
             +--------------------+-------------+-----------+
             |      timeStamp     |      64     |    Yes    |
             |      natEvent      |      8      |    Yes    |
             |    natLimitEvent   |      32     |    Yes    |
             | sourceIPv4 address |      32     |     No    |
             | sourceIPv6 address |     128     |     No    |
             +--------------------+-------------+-----------+

                Table 10: NAT Quota Exceeded event template



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4.4.8.  Address Binding

   This event will be generated when a NAT device binds a local address
   with a global address.  This binding event happens when the first
   packet of the first flow from a host in the private realm.

       +--------------------------------+-------------+-----------+
       |           Field Name           | Size (bits) | Mandatory |
       +--------------------------------+-------------+-----------+
       |            timeStamp           |      64     |    Yes    |
       |            natEvent            |      8      |    Yes    |
       |       sourceIPv4 address       |      32     |     No    |
       |       sourceIPv6 address       |     128     |     No    |
       | Translated Source IPv4 Address |      32     |     8     |
       +--------------------------------+-------------+-----------+

                  Table 11: NAT Address Binding template

4.4.9.  Port block allocation and de-allocation

   This event will be generated when a NAT device allocates/de-allocates
   ports in a bulk fashion, as opposed to allocating a port on a per
   flow basis.  NAT devices would do this in order to reduce logs and
   potentially to limit the number of connections a subscriber is
   allowed to use.  In the following Port Block allocation template, the
   portRangeStart must be specified.  Along with portRangeStart, atleast
   one of portRangeEnd, portRangeStepSize or portRangeNumPorts MUST be
   specified.  If portRangeEnd is specified, it MUST NOT be lesser than
   portRangeStart.  The value of portRangeStepSize MUST be between 1 and
   32K.

              +-------------------+-------------+-----------+
              |     Field Name    | Size (bits) | Mandatory |
              +-------------------+-------------+-----------+
              |     timeStamp     |      64     |    Yes    |
              |   portRangeStart  |      16     |    Yes    |
              |    portRangeEnd   |      16     |     No    |
              | portRangeStepSize |      16     |     No    |
              | portRangeNumPorts |      16     |     No    |
              +-------------------+-------------+-----------+

            Table 12: NAT Port Block Allocation event template


5.  Encoding






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5.1.  IPFIX

   This document uses IPFIX as the encoding mechanism to describe the
   logging of NAT events.  However, the information that should be
   logged SHOULD be the same irrespective of what kind of encoding
   scheme is used.  IPFIX is chosen because is it an IETF standard that
   meets all the needs for a reliable logging mechanism.  IPFIX provides
   the flexibility to the logging device to define the data sets that it
   is logging.  The information elements specified for logging MUST be
   the same irrespective of the encoding mechanism used.


6.  Acknowledgements

   Thanks to Dan Wing, Selvi Shanmugam, Mohamed Boucadir, Jacni Qin
   Ramji Vaithianathan, Simon Perreault, Jean-Francois Tremblay and
   Julia Renouard for their review and comments.


7.  IANA Considerations


8.  Security Considerations

   None.


9.  References

9.1.  Normative References

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

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

   [RFC4787]  Audet, F. and C. Jennings, "Network Address Translation
              (NAT) Behavioral Requirements for Unicast UDP", BCP 127,
              RFC 4787, January 2007.

   [RFC5382]  Guha, S., Biswas, K., Ford, B., Sivakumar, S., and P.
              Srisuresh, "NAT Behavioral Requirements for TCP", BCP 142,
              RFC 5382, October 2008.

   [RFC6146]  Bagnulo, M., Matthews, P., and I. van Beijnum, "Stateful
              NAT64: Network Address and Protocol Translation from IPv6



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              Clients to IPv4 Servers", RFC 6146, April 2011.

9.2.  Informative References

   [NAT-EVENT-LOG-IANA]
              IANA, "NAT event log entities", 2012, <http://
              www.iana.org/assignments/nat-event-log/nat-event-log.xml>.

   [RFC5101]  Claise, B., "Specification of the IP Flow Information
              Export (IPFIX) Protocol for the Exchange of IP Traffic
              Flow Information", RFC 5101, January 2008.

   [RFC5102]  Quittek, J., Bryant, S., Claise, B., Aitken, P., and J.
              Meyer, "Information Model for IP Flow Information Export",
              RFC 5102, January 2008.

   [RFC5470]  Sadasivan, G., Brownlee, N., Claise, B., and J. Quittek,
              "Architecture for IP Flow Information Export", RFC 5470,
              March 2009.


Authors' Addresses

   Senthil Sivakumar
   Cisco Systems
   7100-8 Kit Creek Road
   Research Triangle Park, North Carolina  27709
   USA

   Phone: +1 919 392 5158
   Email: ssenthil@cisco.com


   Renaldo Penno
   Cisco Systems
   170 W Tasman Drive
   San Jose, California  95035
   USA

   Phone:
   Email: repenno@cisco.com










Sivakumar & Penno         Expires July 18, 2013                [Page 14]


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