[homenet] Comments requested for draft CER-ID

Michael Kloberdans <M.Kloberdans@cablelabs.com> Mon, 27 October 2014 13:03 UTC

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From: Michael Kloberdans <M.Kloberdans@cablelabs.com>
To: "homenet@ietf.org" <homenet@ietf.org>
Thread-Topic: Comments requested for draft CER-ID
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Subject: [homenet] Comments requested for draft CER-ID
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As co-chair of the Homenet working group, Mark Townsley suggested that the Homenet group provide comments on the CER-ID (Customer Edge Router Identification), draft before adding it to the Homenet agenda for IETF-91.

This draft proposes a DHCP option that explicitly identifies a specific home router as the edge between the boundary of the public and private networks at the home.  The CER has a public-facing interface and one or more internal-facing interface(s).  Conversely, it also identifies internal routers that are not at the boundary edge.  Knowing the edge is important for applying services such as a firewall, NAPT and requesting IPv6 PDs.

This draft also provides a mechanism to change the default automatically or manually assigned edge router.  This draft peacefully co-exists with other border detection and other assignment methods.  The CER-ID draft features have already been incorporated into Cable Industry specifications for eRouter (Cable Modem integrated into a routing, switching unit), but could also be helpful to TELCO and other industries.

Flexibility was built-in by allowing multiple numbering schemes to identify the CER, including up to 128-bits for an IPv6 address.  A simple number can also be used to act as a flag if desired.  Again, the ability to manually or automatically move the designation of the edge router is available by using a double colon ‘::’ in the CER-ID field and indicates that router is NOT the Edge router.

Behaviors resulting from the knowledge of the CER are left to other implementations.  One implementation detects the CER and disables firewall, NAPT and allocates PD requests for all Internal Routers (non-CER), but this is just one example of applying behaviors based on knowing where the CER lies.

Please read this short draft below and provide comments.


Network Working Group                                          C. Donley
Internet-Draft                                             M. Kloberdans
Intended status: Informational                                 CableLabs
Expires: February 13, 2015                                 J. Brzozowski
                                                           C. Grundemann
                                                         August 12, 2014

               Customer Edge Router Identification Option


   Addressing mechanisms supporting DHCPv6 Prefix Delegation in home
   networks such as those described in CableLabs' eRouter specification
   and the HIPnet Internet-Draft require identification of the customer
   edge router (CER) as the demarcation between the customer network and
   the service provider network.  This document reserves a DHCPv6 option
   to identify the CER.

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 February 13, 2015.

Copyright Notice

   Copyright (c) 2014 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents

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   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.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   2
   2.  CER Identification Option . . . . . . . . . . . . . . . . . .   2
   3.  CER-ID Compatibility  . . . . . . . . . . . . . . . . . . . .   4
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   4
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   Some addressing mechanisms supporting DHCPv6 Prefix Delegation in
   home networks such as those described in
   [I-D.grundemann-homenet-hipnet] and [EROUTER] require identification
   of the customer edge router as the demarcation between the customer
   network and the service provider network.  For prefix delegation
   purposes, it is desirable for other routers within the home to know
   which device is the CER so that the customer home network only
   requests a single prefix from the ISP DHCPv6 server, and efficiently
   distributes this prefix within the home.  CER-ID is a 128-bit string
   that optionally represents an IPV6 address, or another arbitrary
   number.  The CER-ID maybe treated as a hint to be used with border
   detection methods.  This document reserves a DHCPv6 option to be used
   to identify the CER.

1.1.  Requirements Language

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

2.  CER Identification Option

   A Customer Edge Router (CER) sets the CER_ID to the IPv6 address of
   its LAN interface.  If it has more than one LAN IPv6 address, it
   selects one of its LAN or loopback IPv6 addresses to be used in the
   CER_ID.  An ISP server does not respond with the CER_ID or sets the

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   CER_ID to ::.  Such a response or lack of response indicates to the
   DHCPv6 client that it is the CER.

   The format of the CER Identification option is:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   |      option-code              |      option-len               |
   |                                                               |
   |                           CER_ID                              |
   |                                                               |
   |                                                               |
       option-code          OPTION_CER_ID (TBD).
       option-len           36
       CER_ID value         IPv6 address of CER or ::

   Figure 1.

   A DHCPv6 client SHOULD include the CER Identification option code in
   an Option Request option [RFC3315] in its DHCP Solicit messages.

   The DHCPv6 server MAY include the CER Identification option in any
   response it sends to a client that has included the CER
   Identification option code in an Option Request option.  The CER
   Identification option is sent in the main body of the message to
   client, not as a sub-option in, e.g., an IA_NA, IA_TA

   When sending the CER Identification option, the DHCPv6 server MUST
   set the CER_ID value to either one of its IPv6 addresses, another
   identifier, or ::. If a device does not receive the CER
   Identification Option or receives a CER ID of :: from the DHCPv6
   server, it MUST include one of its Globally Unique IPv6 addresses
   (unless another identifier is used), in the CER_ID value in response
   to DHCPv6 messages received by its DHCPv6 server that contains the
   CER Identification option code in an Option Request option.  If the
   device has only one LAN interface, it SHOULD use its LAN IPv6 address
   as the CER_ID value.  If the device has more than one LAN interface,
   it SHOULD use the lowest Globally Unique address not assigned to its
   WAN interface.

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3.  CER-ID Compatibility

   CER-ID explicitly indicates that a gateway is, or is not, the
   demarcation point between public and private networks by containing a
   reachable IPv6 address, other identifier or a double colon '::'
   (double colon indicates that the CER-ID sender is NOT the edge
   router), and as a compliment, can be applied to various border
   definitions and detection methods such as:

   o  I.D.  Draft-IETF-Homenet-Arch-16 [I-D.ietf-homenet-arch]

   o  I.D.  Draft-Grundemann-homenet-HIPnet-01

   o  I.D.  Draft-IETF-Kline-Homenet-Default-Perimeter-01

   o  Others, including manual configuration

4.  IANA Considerations

   IANA is requested to assign an option code from the "DHCP Option
   Codes" Registry for OPTION_CER_ID.  IANA is also requested to
   maintain a list of authentication options.

5.  Security Considerations

   The security of a home network is an important consideration.  Both
   the HIPNet [I-D.grundemann-homenet-hipnet] and Homenet
   [I-D.ietf-homenet-arch] approaches change the operational model of
   the home network vs. today's IPv4-only paradigm.  Specifically, these
   networks eliminate NAT inside the home network (and only enable it
   for IPv4 at the edge router, if required), support global
   addressability of devices, and thus need to consider firewall and/or
   filter support in various home routers.  As the security profile of
   these home routers can shift based on their position in the network
   (e.g., edge vs. internal), security can be severely compromised if
   routers misidentify their border and mistakenly reduce or eliminate
   firewall rules.  If the CER-ID option is used as part of the border
   detection algorithm, it becomes a natural, but not the only place to
   enact firewall, NAT, Prefix Delegation and other functions in the
   home network.

6.  Acknowledgements

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7.  References

7.1.  Normative References

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

   [RFC3315]  Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C.,
              and M. Carney, "Dynamic Host Configuration Protocol for
              IPv6 (DHCPv6)", RFC 3315, July 2003.

7.2.  Informative References

   [EROUTER]  CableLabs, "CableLabs IPv4 and IPv6 eRouter Specification
              (CM-SP-eRouter-I12-131120)", April 2014.

              Grundemann, C., Donley, C., Brzozowski, J., Howard, L.,
              and V. Kuarsingh, "A Near Term Solution for Home IP
              Networking (HIPnet)", draft-grundemann-homenet-hipnet-01
              (work in progress), February 2013.

              Chown, T., Arkko, J., Brandt, A., Troan, O., and J. Weil,
              "IPv6 Home Networking Architecture Principles", draft-
              ietf-homenet-arch-16 (work in progress), June 2014.

              Kline, E., "Default Border Definition", draft-kline-
              default-perimeter-01 (work in progress), November 2012.

Authors' Addresses

   Chris Donley
   858 Coal Creek Cir.
   Louisville, CO  80027

   Email: c.donley@cablelabs.com<mailto:c.donley@cablelabs.com>

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   Michael Kloberdans
   858 Coal Creek Cir
   Louisville, CO  80027

   Email: m.kloberdans@cablelabs.com<mailto:m.kloberdans@cablelabs.com>

   John Brzozowski
   1306 Goshen Parkway
   West Chester, PA  19380

   Email: john_brzozowski@cable.comcast.com<mailto:john_brzozowski@cable.comcast.com>

   Chris Grundemann
   Denver  CO

   Email: cgrundemann@gmail.com<mailto:cgrundemann@gmail.com>

Donley, et al.          Expires February 13, 2015               [Page 6]

Michael Kloberdans
Lead Architect / Home Networking     CableLabs®

858 Coal Creek Circle.  Louisville, CO. 80027
303-661-3813 (v)