6man Working Group S. Krishnan Internet-Draft A. Kavanagh Intended status: Standards Track Ericsson Expires: February 5, 2011 S. Ooghe Alcatel-Lucent B. Varga Magyar Telekom E. Nordmark Oracle August 4, 2010 Line identification in IPv6 Router Solicitation messages draft-krishnan-6man-rs-mark-06 Abstract In Ethernet and PON based aggregation networks, several subscriber premises may be logically connected to the same interface of an edge router. This document proposes a method for the edge router to identify the subscriber premises using the contents of the received Router Solicitation messages. The applicability is limited to the N:1 VLAN allocation model. 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 5, 2011. Copyright Notice Copyright (c) 2010 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 Krishnan, et al. Expires February 5, 2011 [Page 1] Internet-Draft Line Identification in RS August 2010 (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. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Conventions used in this document . . . . . . . . . . . . . 3 2. Issues with identifying the subscriber in an N:1 VLAN model . . 4 3. Applicability . . . . . . . . . . . . . . . . . . . . . . . . . 4 4. Basic operation . . . . . . . . . . . . . . . . . . . . . . . . 4 5. Access Node Behavior . . . . . . . . . . . . . . . . . . . . . 4 5.1. On receiving a Router Solicitation from the subscriber . . 5 5.2. On receiving a Router Advertisement from the subscriber . . 5 6. Edge Router Behavior . . . . . . . . . . . . . . . . . . . . . 5 6.1. On receiving a Router Solicitation from the subscriber . . 5 6.2. On sending a Router Advertisement towards the subscriber . . . . . . . . . . . . . . . . . . . . . . . . 5 7. Line Identification Option . . . . . . . . . . . . . . . . . . 6 8. Interactions with Secure Neighbor Discovery . . . . . . . . . . 7 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7 10. Security Considerations . . . . . . . . . . . . . . . . . . . . 8 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 8 12. Normative References . . . . . . . . . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8 Krishnan, et al. Expires February 5, 2011 [Page 2] Internet-Draft Line Identification in RS August 2010 1. Introduction DSL is a widely deployed access technology for Broadband Access for Next Generation Networks. While traditionally DSL access networks were PPP based some networks are migrating from the traditional PPP access model into a pure IP-based Ethernet aggregated access environment. Architectural and topological models of an Ethernet aggregation network in context of DSL aggregation are described in [TR101]. One of the Ethernet and PON aggregation models specified in this document bridges sessions from multiple subscribers behind a DSL Access Node (AN), also referred to as a DSLAM, into a single VLAN in the aggregation network. This is called the N:1 VLAN allocation model. +---+ +----+ +----------+ |CPE|---| RG |----| | +---+ +----+ | | | AN |\ +---+ +----+ | | \ |CPE|---| RG |----| | \ +---+ +----+ +----------+ \ +----------+ \ | | +-------------+ | | | Aggregation | | Edge | | Node |-------| Router | +-------------+ | | / | | +----------+ / +----------+ | | / +---+ +----+ | | / |CPE|---| RG |----| AN |/ +---+ +----+ | | | | +----------+ Figure 1: Broadband Forum Network Architecture 1.1. Conventions used in this document 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]. Krishnan, et al. Expires February 5, 2011 [Page 3] Internet-Draft Line Identification in RS August 2010 2. Issues with identifying the subscriber in an N:1 VLAN model In a fixed Broadband Network, IPv6 hosts are connected to an Access Node (AN). These hosts today will typically send a Router Solicitation Message to the Edge Router, to which the Edge Router responds with a Router Advertisement message. The Router Advertisement typically contains a prefix that the host will use to automatically configure an IPv6 Address. Upon sending the Router Solicitation message the node connecting the host on the access circuit, typically an Access Node (AN), would forward the RS to the Edge Router upstream over a switched network. However, in such Ethernet-based aggregation networks, several subscriber premises may be connected to the same interface of an edge router (e.g. on the same VLAN). However, the edge router requires some information to identify the host on the circuit line the host is connected on. To accomplish this, the AN needs to add line identification information to the Router Solicitation message and forward this to the Edge Router. This is analogous to the case where DHCP is being used, and the line identification information is inserted by a DHCP relay agent. This document proposes a method for the edge router to identify the subscriber premises using the contents of the received Router Solicitation messages. 3. Applicability The line identification option is intended to be used only for the N:1 VLAN deployment model. For the other VLAN deployment models there is no need to carry line identification. 4. Basic operation This document recommends tunneling Neighbor discovery packets inside another IPv6 packet that uses a destination option to convey line identification information. The Neighbor discovery packets initiated by the host are left unmodified inside the encapsulating IPv6 packet. In particular, the Hop Limit field of the ND message is not decremented when the packet is being tunneled. This is because ND messages whose Hop Limit is not 255 will be discarded by the receiver of such messages. 5. Access Node Behavior Krishnan, et al. Expires February 5, 2011 [Page 4] Internet-Draft Line Identification in RS August 2010 5.1. On receiving a Router Solicitation from the subscriber When a host sends out a Router Solicitation, it is received by the access node. The AN then tunnels the received Router Solicitation in a newly created IPv6 datagram with the Link Identification Option (LIO). The AN forms a new IPv6 datagram whose payload is the received Router Solicitation message as described in [RFC2473] except that the Hop Limit field of the Router Solicitation message MUST NOT be decremented. If the AN has an IPv6 address, it SHOULD use this address in the Source Address field of the outer IPv6 datagram. Otherwise it MUST use the unspecified address as the Source Address of the outer IPv6 datagram. The destination address of the outer IPv6 datagram MUST be copied from the destination address of the tunneled RS. The AN MUST insert a destination options header between the outer IPv6 header and the payload. It MUST insert a LIO destination option and set the line identification field of the option to contain the subscriber agent circuit identifier corresponding to the logical access loop port of the Access Node from which the RS was initiated. It MUST also insert the hardware address of the client (from the source hardware address of the RS) into the client hardware address field of the option. 5.2. On receiving a Router Advertisement from the subscriber Since the Router Advertisements are unicasted by the edge router towards the subscriber the access node does not need to intercept the downstream Router Advertisements. 6. Edge Router Behavior 6.1. On receiving a Router Solicitation from the subscriber When the edge router receives a tunneled Router Solicitation forwarded by the access node, it needs to check if there is an LIO destination option present in the outer datagram. If an LIO option is present, the edge router MUST verify that the Option Length field of this option is set to ClientHWALen+LineIDLen+2. If not the edge router MUST discard the tunneled Router Solicitation. The edge router can use the contents of the line identification field to lookup the addressing information and policy that need to be applied to the subscriber. The edge router MUST then process the inner RS message as specified in [RFC4861] 6.2. On sending a Router Advertisement towards the subscriber When the edge router sends out a Router Advertisement in response to a tunneled RS that included an LIO option, it MUST unicast the RA at Krishnan, et al. Expires February 5, 2011 [Page 5] Internet-Draft Line Identification in RS August 2010 layer 2 back to the sender of the RS. If the source address of the RS was the unspecified address, then the IPv6 destination address of the RA MUST be set to the all-nodes multicast address, other wise the IPv6 destination address is copied from the inner IPv6 source address of the Router Soliciation. In both cases the link-layer destination address MUST be set to the unicast link-layer address which is in Client Hardware Address field in the LIO. 7. Line Identification Option The Line Identification Option (LIO) is a destination option that can be included in IPv6 datagrams that tunnel Router Solicitation and Router Advertisement messages. Multiple Line Identification options MUST NOT be present in the same IPv6 datagram. The LIO has an alignment requirement of (none). 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 Type | Option Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LineIDLen | Line Identification... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ClientHWALen | Client Hardware Address... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 2: Line Identification Option Layout Krishnan, et al. Expires February 5, 2011 [Page 6] Internet-Draft Line Identification in RS August 2010 Option Type 8-bit identifier of the type of option. The option identifier for the line identification option will be allocated by the IANA. Option Length 8-bit unsigned integer. The length of the option (excluding the Option Type and Option Length fields). The value 0 is considered invalid. LineIDLen Length of the Line Identification field in number of octets. Line Identification Variable length data inserted by the Access Node describing the subscriber agent circuit identifier corresponding to the logical access loop port of the Access Node from which the RS was initiated. ClientHWALen Length of the Client Hardware Address in number of octets. Client Hardware Address Variable length client hardware address as detected by the access node. 8. Interactions with Secure Neighbor Discovery Since the SEND [RFC3971] protected RS/RA packets are not modified in anyway by the mechanism described in this document, there are no issues with SEND verification. 9. Acknowledgements The authors would like to thank Margaret Wasserman, Mark Townsley, David Miles, John Kaippallimalil, Eric Levy-Abegnoli, Thomas Narten, Olaf Bonness, Thomas Haag and Wojciech Dec for reviewing this document and suggesting changes. Krishnan, et al. Expires February 5, 2011 [Page 7] Internet-Draft Line Identification in RS August 2010 10. Security Considerations The line identification information inserted by the access node or the edge router is not protected. This means that this option may be modified, inserted, or deleted without being detected. In order to ensure validity of the contents of the line identification field, the network between the access node and the edge router needs to be trusted. 11. IANA Considerations This document defines a new IPv6 destination option for carrying line identification. IANA is requested to assign a new destination option type in the Destination Options registry maintained at http://www.iana.org/assignments/ipv6-parameters Line Identification Option [RFCXXXX] The act bits for this option need to be 10 and the chg bit needs to be 0. 12. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2473] Conta, A. and S. Deering, "Generic Packet Tunneling in IPv6 Specification", RFC 2473, December 1998. [RFC3971] Arkko, J., Kempf, J., Zill, B., and P. Nikander, "SEcure Neighbor Discovery (SEND)", RFC 3971, March 2005. [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, September 2007. [TR101] Broadband Forum, "Migration to Ethernet-based DSL aggregation", . Krishnan, et al. Expires February 5, 2011 [Page 8] Internet-Draft Line Identification in RS August 2010 Authors' Addresses Suresh Krishnan Ericsson 8400 Blvd Decarie Town of Mount Royal, Quebec Canada Email: suresh.krishnan@ericsson.com Alan Kavanagh Ericsson 8400 Blvd Decarie Town of Mount Royal, Quebec Canada Email: alan.kavanagh@ericsson.com Sven Ooghe Alcatel-Lucent Copernicuslaan 50 2018 Antwerp, Belgium Phone: Email: sven.ooghe@alcatel-lucent.com Balazs Varga Magyar Telekom Email: varga.balazs@telekom.hu Erik Nordmark Oracle 17 Network Circle Menlo Park, CA 94025 USA Email: erik.nordmark@oracle.com Krishnan, et al. Expires February 5, 2011 [Page 9]