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INTERNET-DRAFT                                  Darrel Lewis

                                                  James Gill
                                           Verizon Business.
                                                Darrel Lewis
                                         Cisco Systems, Inc.
                                                  Paul Quinn
                                         Cisco Systems, Inc.
                                           Peter Schoenmaker
                                                 NTT America
October 2006

                Service Provider Infrastructure Security
                <draft-lewis-infrastructure-security-00>



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Copyright Notice

   Copyright (C) The Internet Society (2006)


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      http://www.ietf.org/shadow.html.

      This Internet-Draft will expire on October 28, 2006.



Copyright Notice

   Copyright (C) The Internet Society (2006). All Rights Reserved.

                                Abstract


   This RFC defines best current practices for implementing Service
   Provider network infrastructure protection for network elements.
   This RFC complements and extends RFC 2267 and RFC 3704.  RFC 2267
   provides guidelines for filtering traffic on the ingress to service
   provider networks.  RFC 3704 expands the recommendations described in
   RFC 2267 to address operational filtering guidelines for single and
   multi-homed environments.  The focus of those RFCs is on filtering
   ingress packets ingress, regardless of destination, if those packets
   are have spoofed source address or fall within "reserved" address
   space.  Deployment of RFCs 2267 and 3704 has limited the effects of
   denial of service attacks by dropping ingress packets with spoofed
   source addresses, which in turn offers other benefits by ensuring
   that packets coming into a network originate from validly allocated
   and consistent sources.

   This document focuses solely on traffic destined to the network
   infrastructure itself to protect the network from denial of service
   and other attacks.  This document presents techniques that, together
   with network edge ingress filtering and RFC 2267 and RFC 3704, create
   a layered approach for infrastructure protection.

   This document does not present recommendations for protocol
   validation (i.e. "sanity checking") nor does it address guidelines
   for general security configuration.














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Table of Contents


   1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . .   4
   2. Overview of Infrastructure Protection Techniques . . . . . . .   5
    2.1. Edge Infrastructure Access Control Lists. . . . . . . . . .   5
    2.2. Edge Remarking. . . . . . . . . . . . . . . . . . . . . . .   5
    2.3. Device and Element Protection . . . . . . . . . . . . . . .   6
    2.4. Infrastructure Hiding . . . . . . . . . . . . . . . . . . .   6
   3. Edge Infrastructure Access Control Lists . . . . . . . . . . .   6
    3.1. Constructing the Access List. . . . . . . . . . . . . . . .   7
    3.2. Other Traffic . . . . . . . . . . . . . . . . . . . . . . .   7
    3.3. Edge Infrastructure Conclusion. . . . . . . . . . . . . . .   8
   4. Edge Rewrite/Remarking . . . . . . . . . . . . . . . . . . . .   8
    4.1. Edge Rewriting/Remarking Discussion . . . . . . . . . . . .   9
   5. Device/Element Protection. . . . . . . . . . . . . . . . . . .   9
    5.1. Service Specific Access Control . . . . . . . . . . . . . .  10
     5.1.1. Common Services. . . . . . . . . . . . . . . . . . . . .  10
    5.2. Aggregate Device Access Control . . . . . . . . . . . . . .  10
     5.2.1. IP Fragments . . . . . . . . . . . . . . . . . . . . . .  11
     5.2.2. Performance Considerations . . . . . . . . . . . . . . .  11
     5.2.3. Access Control Implementation Guide. . . . . . . . . . .  11
    5.3. Device Access Authorization and Accounting. . . . . . . . .  11
   6. Infrastructure Hiding. . . . . . . . . . . . . . . . . . . . .  12
    6.1.  Use less IP. . . . . . . . . . . . . . . . . . . . . . . .  12
    6.2. MPLS techniques . . . . . . . . . . . . . . . . . . . . . .  12
    6.3. IGP configuration . . . . . . . . . . . . . . . . . . . . .  12
    6.4. Route advertisement control . . . . . . . . . . . . . . . .  13
     6.4.1. Route Announcement filtering . . . . . . . . . . . . . .  13
     6.4.2. Address core out of rfc1918 space. . . . . . . . . . . .  13
   7. IPv6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  13
    7.1. IPv6 Edge Infrastructure Access Control List. . . . . . . .  14
    7.2. IPv6 Edge Remarking . . . . . . . . . . . . . . . . . . . .  14
    7.3. IPv6 Device and Element Protection. . . . . . . . . . . . .  15
    7.4. IPv6 Infrastructure Hiding. . . . . . . . . . . . . . . . .  15
   8. IP Multicast . . . . . . . . . . . . . . . . . . . . . . . . .  15
    8.1. Multicast Group Protection. . . . . . . . . . . . . . . . .  16
    8.2. Performance Considerations. . . . . . . . . . . . . . . . .  16
    8.3. IPv6 and Multicast. . . . . . . . . . . . . . . . . . . . .  16
   9. Acknowledgments. . . . . . . . . . . . . . . . . . . . . . . .  17
   10. References. . . . . . . . . . . . . . . . . . . . . . . . . .  18
    10.1. Normative References . . . . . . . . . . . . . . . . . . .  18
    10.2. Informative References . . . . . . . . . . . . . . . . . .  18
   11. Authors' Addresses. . . . . . . . . . . . . . . . . . . . . .  19







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1.  Introduction


   This RFC defines best current practices for implementing Service
   Provider network infrastructure protection for network elements.
   RFC 2267 and RFC 3704 focuses on limiting the effects of denial of
   service attacks by filtering ingress packets with spoofed source
   addresses, which in turn offers other benefits by ensuring that
   packets coming into a network originate from validly allocated and
   consistent sources.  RFC 3704 extends the recommendations described
   in RFC 2267 to address operational filtering guidelines for single
   and multi-homed environments.  In both cases (RFC 2267 and RFC 3704),
   the focus is on dropping packets on ingress, regardless of
   destination, if those packets are have spoofed source address or fall
   within "reserved" address space.  This document both refines and
   extends the filtering best practices outlined in RFC 2267 and RFC
   3704 and focuses only on traffic destined to the network
   infrastructure itself to protect the service provider network from
   denial of service and other attacks.  This document presents
   techniques that, together with network edge ingress filtering and RFC
   2267 and RFC 3704, create a layered approach for infrastructure
   protection.

   Denial of Service (DoS) attacks are common and the network
   infrastructure itself is a target.   Attacks targeting the network
   infrastructure can take many forms, ranging from bandwidth saturation
   to crafted packets destined to a router.  These attacks might use
   spoofed source address or they might use the true address of source
   of the traffic.  Regardless of the nature of the attack, the network
   infrastructure must be protected from both accidental and intentional
   attacks.

   The techniques outlined in this document and described in section 2
   below, provide a layered approach for infrastructure protection:
   Edge policy (filtering and precedence), per device traffic policy
   enforcement for packets destined to a device and finally,
   routing/address advertising best practices to limit core network --
   that is P and PE infrastructure -- exposure.

   This document is aimed at network operators who would like to
   "harden" their infrastructure and make it more resilient to external
   attack.  These techniques are designed to be used in addition to
   specific protocol or application security features implemented in
   network devices.

   Infrastructure protection is a complex topic, improving protection is
   always beneficial.




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2.  Overview of Infrastructure Protection Techniques


   This section provides an overview of the four recommended techniques
   that may be used to protect network infrastructure.  The details of
   each area along with some deployment consideration are described in
   detail in subsequent sections.

          - Edge Infrastructure Access Control List
          - Edge Remarking
          - Device and Element Protection
          - Infrastructure Hiding

   The above list is not exhaustive; other mechanisms can be used to
   provide a measure of protection.  The techniques discussed in this
   document have been widely deployment and have proven operational
   security benefits in large networks.




2.1.  Edge Infrastructure Access Control Lists


   Edge infrastructure access control lists are ingress access control
   lists that filter traffic destined to the network only.  They should
   permit all traffic through the network.  Explicit filtering of
   traffic destined to network devices creates a first level of
   protection at the network edge: only traffic explicitly permitted
   into the network can reach a device beyond the PE router with the
   filter.

   Although very effective, edge infrastructure access control lists are
   not perfect and, like any filter lists, must be maintained and
   updated.  Furthermore, while widespread deployment on ingress
   interface provides the most protection (which in some cases will not
   be possible), some deployment is better than no deployment.




2.2.  Edge Remarking


   We define Edge Remarking as ensuring that ingress IP precedence or
   DSCP values match expected values within the context of security.
   This provides another layer of defense particularly for traffic
   permitted through any of the Edge Infrastructure Access Control



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   Lists.   In this RFC we focus only on using Edge Remarking best
   practices to enforce security policies.




2.3.  Device and Element Protection


   Each device infrastructure device should enforce local rules for
   traffic destined to the device itself.  These rules can take the form
   of filters (permit/deny) or rate limiting rules that allow ingress
   traffic at specified rates.  These should complement any existing
   Edge Infrastructure Access Control Lists.

   The deployment of these local device protection rules compliments the
   edge techniques by protecting the device from traffic that: i) was
   permitted but violates device policy, ii) could not be filtered at
   the edge, iii) entered the network on an interface that did not have
   ingress filtering enabled.




2.4.  Infrastructure Hiding


   Hiding the infrastructure of the network provides an elegant
   mechanism for protecting the network infrastructure.  If the
   destination of an attack is to an infrastructure address that is
   unreachable, attacks become far more difficult.  Infrastructure
   hiding can be achieved in several ways:

          -  MPLS techniques
          -  IGP configuration
          -  Route advertisement control





3.  Edge Infrastructure Access Control Lists


   Edge Infrastructure Access Control Lists (EIACLs) are a specific
   implementation of the more general Ingress Access List.  As opposed
   to generic ingress filtering which denies data (sometimes referred to
   as user) plane traffic, edge infrastructure access control lists do



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   not attempt to deny traffic going through the devices, rather this
   form of access control limits traffic destined to infrastructure
   equipment while permitting -- if needed, explicitly -- traffic
   through the network.




3.1.  Constructing the Access List


   Edge Infrastructure Access Control Lists permit only required traffic
   to the network infrastructure, while allowing data plane traffic to
   flow through unaffected. The basic premise of EIACLs is that only a
   relatively limited subset of traffic, sourced from outside your AS,
   needs to be destined for a core router and that by explicitly
   permitting only that known and understood traffic, the core devices
   are not subjected to unnecessary traffic that might result in a
   denial of service attack.

   Since edge infrastructure access control lists protect only the
   infrastructure, the development of the list differs somewhat from
   "traditional" access filter lists:

          1. Review addressing scheme, and identify address block(s)
   that represent core devices.

          2. Determine what traffic must be destined to the core devices
   from outside the AS.

          3. Create a filter that allow the required traffic, denies all
   traffic destined to the core address block and then finally, permits
   all other traffic to all.

   As with other ingress filtering techniques, EIACLs are applied on
   ingress into the network, and clearly comprehensive coverage (i.e. on
   as many interface as possible) yields the most protection.



3.2.  Other Traffic


   In addition to the explicitly permitted traffic, EIACLs can be
   combined with other common edge filters such as:

          1. Source spoof prevention (as per RFC 3704) by denying
   internal AS addresses as external sources.



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          2. Filtering of reserved addresses (e.g. rfc1918 addresses) as
   traffic should not be sourced from reserved address.
          3. Other unneeded or unnecessary traffic

   Filtering this traffic can be part of the list explicitly or
   implicitly, however, explicit filters often provides log-able
   information that can be of use during a security event.




3.3.  Edge Infrastructure Conclusion


   Edge Infrastructure Access Control Lists provide a very effective
   first line of defense.  To deploy them effectively, core address
   space must be identifiable and widespread deployment is necessary.




4.  Edge Rewrite/Remarking


   RFC 1812 section 5.3 defines the use of IP Preference in IPv4 packets
   for routing, management and control traffic.  In addition it
   recommends devices use a mechanism for providing preferential
   forwarding for packets marked as routing, management or control
   traffic using IP Preference bits 6 or 7 (110 or 111 in binary.)
   RFC2474 defines DSCP and the compatibility of IP Preference bits when
   using DSCP.

   All packets received from the Customer edge (CE,) and the Peer Edge
   by the Provider Edge (PE,) with IP Preference values of 6 or 7 or
   DSCP bits of 11xxxx, as specified in RFC2474 Differentiated Services
   Field Definition, should have the IP Preference bits rewritten.
   Routing traffic received from the CE and the Peer Edge can safely
   have the IP Preference bits rewritten, because only a limited number
   of protocols are transmitted beyond the first PE router.  The bits
   may be rewritten to any value other than IP Preference values 6 or 7,
   or any DSCP value other than 11xxxx.  The new value can be based on
   the network operators IP Preference or DSCP policy.  If no policy
   exists the bits should be rewritten to 0.

   Providers may not want to modify traffic that goes through their
   network in an effort offer a fully transparent service.  If the
   provider relies on alternative means of classifying traffic for
   prioritized forwarding rewriting the IP Preference bits is not



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   required.  Alternatives include encapsulating customer traffic into a
   second protocol, such as MPLS, GRE, and IP, or using an Access
   Control List (ACL) to classify legitimate routing, management, and
   control traffic.  When encapsulating traffic into a second protocol,
   policy must ensure that IP Preference bits 6 and 7 are not
   transferred to the preference field of encapsulating protocol. In
   this example the EXP bits or IP Preference/DSCP bits.  A longer tuple
   used for identifying routing, management and control traffic will
   provide a higher level of security than a shorter one.  Other
   techniques may exist not covered in this document.





4.1.  Edge Rewriting/Remarking Discussion


   By default router vendors do not differentiate an interface on a PE
   router connected to a P router from an interface connected to a CE
   router.  As a result any packet with the proper IP Preference or DSCP
   bits set may receive the same preferential forwarding behavior as
   legitimate routing, management, and control traffic.  A malicious
   attack may be able to take advantage of the vulnerability to increase
   the effectiveness of the attack or to attack the routing, management,
   and/or control traffic directly.

   This document is aimed at protecting network infrastructure from
   traffic to the device rather than traffic through the device.  Even
   though the edge rewrite/remarking deals primarily with traffic
   through a device it is included because the traffic has a direct
   impact on traffic to a device.  The forwarding prioritization given
   to routing, management, and control traffic by default leaves devices
   vulnerable to indirect attacks to the core infrastructure.




5.  Device/Element Protection


   Even with the widest possible deployment of the techniques described
   above in the section Infrastructure Edge Access Control, the
   individual devices of the network must implement access control
   mechanisms.  This is because in addition to the case of incomplete or
   imperfect deployment of edge infrastructure control, threats may
   occur from trusted sources within the perimeter of the network.




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5.1.  Service Specific Access Control


   Typically these mechanisms are not concerned with protecting the
   system as a whole, but the service from exploitation.  The goal is
   not overall system availability, but maximizing the security of the
   particular service.



5.1.1.  Common Services


   While each service implemented by network equipment manufacturers
   differs in its available security features there are some common
   services and security features for those services that have been
   widely deployed.

   The most important first step for the operator is to disable any
   unneeded/unused services.

   Second, the operator should utilize the services access control
   mechanisms to limit the access to the devices service to only
   required sources.  Examples are using virtual terminal access control
   lists, or SNMP Community access control lists.





5.2.  Aggregate Device Access Control


   The device must be protected from denial of service threats, in
   addition, aggregating the security policy allows for a simplified
   view of the access policies traffic going to the device.

   A key requirement of these mechanisms is that it must not impact
   transit data plane traffic.  In addition, these mechanisms should not
   make the device more vulnerable to malicious traffic than not using
   them.










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5.2.1.  IP Fragments


   Traffic destined to a router is not typically fragmented.  Fragment
   keywords or other mechanisms to deny fragments to the device are
   recommended.



5.2.2.  Performance Considerations


   Care should be taken to understand a vendors implementation of this
   functionality and to make sure that device operation is not impaired
   during DoS attacks against the device.





5.2.3.  Access Control Implementation Guide


   Implementing a complex set of access controls for all traffic going
   to and from a router is non trivial.  The following is a recommended
   set of steps that has been used successfully by many carriers.

          -Develop list of required protocols
          -Develop source address requirements
          -Determine destination interface on router
          Does the protocol access a single interface?
          Does the protocol access many interfaces?
          Does the protocol access a virtual or physical interfaces?
          -Deployment should be an iterative process
          -Start with relatively open lists then tighten as needed



5.3.  Device Access Authorization and Accounting


   Operators should use per command authorization and accounting
   wherever possible.  Aside from their utility in mitigating other
   security threats, they provide an invaluable tool in the post event
   forensics.






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6.  Infrastructure Hiding


   Hiding the infrastructure of the network provides an elegant
   mechanism for protecting the network infrastructure.  If the
   destination of an attack is to an infrastructure address that is
   unreachable, attacks become far more difficult.  Infrastructure
   hiding can be achieved in several ways:



6.1.  Use less IP


   One way to reduce exposure of network infrastructure is to use
   unnumbered links wherever possible.  This is particularly useful for
   customers in the simple case of a single provider with a default path
   to the Internet.





6.2.  MPLS techniques


   While it may not be feasible to hide the entire infrastructure of
   large networks from edge to edge using MPLS, it is certainly possible
   to reduce exposure of critical core infrastructure beyond the first
   hop by creating an MPLS mesh where TTL is not decremented as packets
   pass through it.  In this manner the number, addresses, and even
   existence of intermediary devices can be hidden from traffic as it
   passes through the core.





6.3.  IGP configuration


   Using a non-IP control plane for the core routing protocol can
   substantially reduce the number of IP addresses that
   [comprise/expose] the core. This simplifies the task of maintaining
   edge ACLs or route announcement filters.  IS-IS is an elegant and
   mature protocol that may be suitable for this task.





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6.4.  Route advertisement control




6.4.1.  Route Announcement filtering


   Inasmuch as it is unavoidable that some network elements must be
   configured with IP addresses, it may be possible to assign these
   address out of netblocks for which the routing advertisement can be
   filtered, thereby limiting possible sources of traffic to core
   netblocks down to customers for which you provide a default route, or
   direct peers who would make the effort to create a static route for
   your core netblock into your AS.

   Further, it may be possible in those situations where customer point-
   to-point links must be numbered, to address such links out of another
   range of addresses for which announcements could be similarly
   filtered.  While this has implications for a customer's ability to
   remote-monitor their circuit, this can often be overcome with
   application of an address from the customer's routed space to the CPE
   loopback.




6.4.2.  Address core out of rfc1918 space


   In addition to filtering the visibility of core addresses to the
   wider Internet, it may be possible to use rfc1918 netblocks for
   numbering infrastructure when IP addresses are required (eg,
   loopbacks).  This added level of obscurity takes prevention of wide
   distribution of your infrastructure address space one step further.
   Many networks filter out packets with rfc1918 address at
   ingress/egress points as a matter of course.  In this circumstance,
   tools such as traceroute can work through your core, but reverse-
   resolution of descriptive names should be restricted to queries from
   internal/support groups.




7.  IPv6


   IPv6 Networks contain the same infrastructure security risks as IPv4.



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   All techniques described in this document for IPv4 should be directly
   applicable to IPv6 networks.  Limitations exist where devices do not
   have feature parity between IPv4 and IPv6.  Different techniques
   maybe required where IPv4 and IPv6 networks deviate in
   implementation.  Multi-vendor networks create greater difficulties
   when each vendor does not have feature parity with each other.

   Hardware differences in devices that support both IPv4 and IPv6 must
   also be taken into consideration.  Because IPv6 uses a longer address
   space the scaling, and performance characteristics of ACLs maybe
   lower for IPv6 vs IPv4.    The fields or number of fields that an ACL
   can match on may also differ.

   The fact that all PE devices do not support all the recommended ipv6
   security features should not preclude the implementation of the
   recommendations in this document on the devices that do support the
   security features.

   With the number of Network Operators deploying IPv6 growing, along
   with the continued availability of IPv6 Tunnel services, connecting
   to the IPv6 internet is less difficult.  Dual stack IPv6 networks run
   on 10Gbps and greater backbones with edge speeds equal to IPv4.
   Neither the edge nor the core limit potential IPv6 attacks.





7.1.  IPv6 Edge Infrastructure Access Control List


   The same process should be used for constructing the IPv6 eiacl as
   the IPv4 eiacl.




7.2.  IPv6 Edge Remarking


   IPv6 DSCP bits should be rewritten in the same manner that IPv4 DSCP
   bits.









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7.3.  IPv6 Device and Element Protection


   IPv6 device and element protection should be implemented using the
   same policy as IPv4.




7.4.  IPv6 Infrastructure Hiding


   Network operators may deploy IPv4 differently from IPv6 in their
   network.  Providers may use native forwarding for IPv6 while using
   MPLS for IPv4, other combinations.  IPv6 infrastructure hiding should
   have parity with IPv4 infrastructure hiding even if the technique
   used is different.

   Implementation of IPv6 route advertisement control for infrastructure
   hiding is difficult when using global address space.  It is difficult
   to get non-continuous network blocks from the address registries, and
   de-aggregation of IPv6 address space is not an acceptable
   alternative.  It is still possible to use private address space as a
   way of restricting IPv6 advertisements.



8.  IP Multicast


   IP Multicast behaves differently from IP unicast therefore must be
   secured in a different manner.  Some of the protocols used with
   Multicast rely on IP unicast to transport the routing, and control
   information.  Unicast based protocols should be secured using the
   technique described in much of this document.  Because this document
   is focused on hardening a service providers infrastructure rather
   than validating routing announcements, much of IP Multicast filtering
   will be better covered in other documents.

   In much the same way a host must listen on a certain IP address and
   port for an IP unicast connection, Multicast must join a group in
   order to receive any information via Multicast.  The major difference
   is that multicast groups are global and not assigned to a specific
   customer or end user.  Administrative boundaries and scope are
   created to isolate Multicast groups within one network or desired
   area.





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8.1.  Multicast Group Protection


   Certain Multicast groups should never been joined from outside an
   operators network or administrative boundary.  Filters should be
   placed on the protocols used to communicate with external hosts and
   networks.  IGMP should have a join filter to prevent hosts from
   joining internal groups.  MSDP should be configured with a Source
   Address (SA) filter to prevent other networks from joining internal
   groups.

   EIACLs should include administratively bounded multicast groups,
   along with any groups used for protocols internal to a providers
   network.

   When constructing router Access Control as described in section
   5.2.4, multicast protocols must be taken into consideration.




8.2.  Performance Considerations


   Multicast protocols and implementation have different performance and
   scaling limitation than IP unicast.  Multicast users create state on
   the router every time the user joins a group.  Router resources can
   be exhausted if the amount of state created exceeds the resources
   available on the router.  Placing limits on the resources used by the
   Multicast protocols can prevent collateral damage to services other
   than Multicast on a router. MSDP should have a limit placed on the
   number of SA announcements received.  A fixed limit should be placed
   on the number of entries the router stores in the IP Multicast
   routing table.  The number of SAP entries should have a limit placed
   on them.





8.3.  IPv6 and Multicast


   IPv6 Multicast policy should be consistent with the IP Multicast
   policy.  9.0 Security Considerations






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9.  Acknowledgments


















































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10.  References

10.1.  Normative References


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

   [REF]           Reference....


10.2.  Informative References



   [RFC3667]       Bradner, S., "IETF Rights in Contributions",
                   BCP 78, RFC 3667, February, 2004.

   [RFC3668]       Bradner, S., "Intellectual Property Rights in
                   IETF Technology", BCP 79, RFC 3668, February,
                   2004.

   [RFC2434]       Narten, T., and H. Alvestrand, "Guidelines for
                   Writing an IANA Considerations Section in RFCs",
                   BCP 26, RFC 2434, October 1998.

























Gill, Lewis, Quinn, Schoenmaker                 Section 10.2.  [Page 18]


INTERNET-DRAFT                  Expires:                       October 2006


11.  Authors' Addresses



   James Gill
   TBD


   Darrel Lewis
   Cisco Systems Inc.
   170 West Tasman Drive
   San Jose, CA 95134
   Phone: +1 408 853 3653
   EMail:  darlewis@cisco.com

   Paul Quinn
   170 West Tasman Drive
   San Jose, CA 95134
   Phone: +1 408 527 3560
   Email: paulq@cisco.com

   Peter Schoenmaker
   NTT America
   101 Park Ave., FL 41
   New York, NY  10178
   +1-212-808-2298
   pds@ntt.net




Intellectual Property Statement

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   Copies of IPR disclosures made to the IETF Secretariat and any
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   attempt made to obtain a general license or permission for the use of
   such proprietary rights by implementers or users of this
   specification can be obtained from the IETF on-line IPR repository at
   http://www.ietf.org/ipr.



Gill, Lewis, Quinn, Schoenmaker                   Section 11.  [Page 19]


INTERNET-DRAFT                  Expires:                       October 2006


   The IETF invites any interested party to bring to its attention any
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Acknowledgment

   Funding for the RFC Editor function is currently provided by the
   Internet Society.























Gill, Lewis, Quinn, Schoenmaker                   Section 11.  [Page 20]


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