Homenet Working Group S. Barth
Internet-Draft Independent
Intended status: Experimental October 16, 2015
Expires: April 18, 2016

Home Network WiFi Roaming


This document describes a mechanism to manage host routes and statelessly proxy IPv6 Duplicate Address Detection messages between multiple WiFi links to allow client roaming.

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/.

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This Internet-Draft will expire on April 18, 2016.

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Copyright (c) 2015 IETF Trust and the persons identified as the document authors. All rights reserved.

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Table of Contents

1. Introduction

In a multi router home network it can be desirable to have a WiFi network accessible in different physical locations. Synchronization of configuration parameters like ESSID and authentication allows clients to seamlessly roam the network. However, a client switching from one WiFi AP to another might suffer from service disruption if each AP uses a different IP address prefix. To mitigate this issue, all AP links could be bridged on layer 2, which would lead to increased traffic on the home network backbone. This draft offers an alternative solutions based on host routing and proxying of Duplicate Address Detection for IPv6.

In order to minimize additional complexity on routers, this draft either relies on existing state in the form the neighbor cache entries used for host routing or introduces only lightweight, stateless mechanism to distribute Duplicate Address Detection messages.

However, an additional mechanism is needed to identify and share information about which routers have roaming interfaces, to which roaming interface set they belong, under which addresses these routers are reachable and which specific roaming prefixes are assigned. The specific mechanism is out of scope for this draft, however a solution based on [I-D.ietf-homenet-hncp] is conceivable.

2. Terminology

ESSID IEEE 802.11 Extended Service Set Identifier
host route an IPv6 route with a prefix length of 128 intended to track a host on a roaming interface
roaming interface a network interface (typically IEEE 802.11) which shares an address prefix with other similar interfaces to allow seamless client roaming
roaming interface set the set of roaming interfaces which share a particular address prefix
roaming prefix an IPv6 address prefix shared between all interfaces in a roaming interface set

2.1. Requirements Language

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119].

3. Stateless Duplicate Address Detection (DAD) Proxy

Sharing a roaming prefix across multiple separate interfaces might lead to address collisions between hosts on different interfaces of the same set. Therefore, it needs to be ensured that DAD messages are shared across interfaces. The typical DAD process involves the querying host sending one or more Neighbor Solicitations using the unspecified address as a source and any colliding host replying to the all-nodes address as specified in [RFC4862] and [RFC4861]. Since the source addresses of the DAD solicitations and the destination addresses of the DAD advertisements are fixed, the whole process can happen statelessly.

3.1. Receipt of DAD Messages and forwarding to routers

The following requirements apply for receiving DAD traffic from hosts on roaming interfaces and forwarding them to other DAD proxy routers:

3.2. Distributing DAD Messages received from other routers

The following requirements apply for distributing DAD traffic, forwarded by other routers, to clients on roaming interfaces:

4. Maintaining Host Routes

Host routes are necessary in order to unambiguously forward packets to potentially roaming WiFi clients. This draft ties the announcement of host routes to the presence of Neighbor Cache [RFC4861] entries for addresses of roaming prefixes. The following requirements apply:

5. Roaming Interface Configuration

The following requirements are suggested for interfaces intended to use the roaming features described in this draft:

6. Security Considerations


7. IANA Considerations

No action needed.

8. References

8.1. Normative references

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997.
[RFC4861] Narten, T., Nordmark, E., Simpson, W. and H. Soliman, "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, DOI 10.17487/RFC4861, September 2007.
[RFC4862] Thomson, S., Narten, T. and T. Jinmei, "IPv6 Stateless Address Autoconfiguration", RFC 4862, DOI 10.17487/RFC4862, September 2007.
[I-D.ietf-v6ops-reducing-ra-energy-consumption] Yourtchenko, A. and L. Colitti, "Reducing energy consumption of Router Advertisements", Internet-Draft draft-ietf-v6ops-reducing-ra-energy-consumption-02, October 2015.

8.2. Informative references

[I-D.ietf-homenet-hncp] Stenberg, M., Barth, S. and P. Pfister, "Home Networking Control Protocol", Internet-Draft draft-ietf-homenet-hncp-09, August 2015.

Appendix A. Discussion Points [RFC Editor: please remove]

Appendix B. Changelog [RFC Editor: please remove]


Appendix C. Draft Source [RFC Editor: please remove]

As usual, this draft is available at https://github.com/fingon/ietf-drafts/ in source format (with nice Makefile too). Feel free to send comments and/or pull requests if and when you have changes to it!

Appendix D. Acknowledgements

Thanks to Markus Stenberg for comments and feedback on the draft.

Author's Address

Steven Barth Independent Halle, 06114 Germany EMail: cyrus@openwrt.org