Network Working Group J. Chroboczek
Internet-Draft PPS, University of Paris-Diderot
Intended status: Experimental March 21, 2016
Expires: September 22, 2016

Homenet profile of the Babel routing protocol


This document defines the subset of the Babel routing protocol [RFC6126] and its extensions that a Homenet router must implement.

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Table of Contents

1. Introduction

The core of the Homenet protocol suite consists of HNCP [HNCP], a protocol used for flooding configuration information and assigning prefixes to links, combined with the Babel routing protocol [RFC6126]. Babel is an extensible, flexible and modular protocol: minimal implementations of Babel have been demonstrated that consist of a few hundred of lines of code, while the "large" implementation includes support for a number of extensions and consists of over ten thousand lines of C code.

This document defines the exact subset of the Babel protocol and its extensions that is required by a conformant implementation of the Homenet protocol suite.

1.1. Background

The Babel routing protocol and its extensions are defined in a number of documents:

2. The Homenet profile of Babel

2.1. Requirements

REQ1: a Homenet implementation of Babel MUST encapsulate Babel control traffic in IPv6 packets sent to the IANA-assigned port 6696 and either the IANA-assigned multicast group ff02::1:6 or to a link-local unicast address.

REQ2: a Homenet implementation of Babel MUST implement the IPv6 subset of the protocol defined in the body of RFC 6126.

REQ3: a Homenet implementation of Babel SHOULD implement the IPv4 subset of the protocol defined in the body of RFC 6126. Use of other techniques for acquiring IPv4 connectivity (such as multiple layers of NAT) is strongly discouraged.

REQ4: a Homenet implementation of Babel MUST implement source-specific routing for IPv6, as defined in draft-boutier-babel-source-specific [BABEL-SS]. This implies that it MUST implement the extension mechanism defined in RFC 7557.

REQ5: a Homenet implementation of Babel MUST implement HMAC-based authentication, as defined in RFC 7298, MUST implement the two mandatory-to-implement algorithms defined in RFC 7298, and MUST enable and require authentication when instructed to do so by HNCP.

REQ6: a Homenet implementation of Babel MUST use metrics that are of a similar magnitude to the values suggested in Appendix A of RFC 6126. In particular, it SHOULD assign costs that are no less than 256 to wireless links, and SHOULD assign costs between 32 and 196 to lossless wired links.

REQ7: a Homenet implementation of Babel SHOULD distinguish between wired and wireless links; if it is unable to determine whether a link is wired or wireless, it SHOULD make the worst-case hypothesis that the link is wireless. It SHOULD dynamically probe the quality of wireless links and derive a suitable metric from its quality estimation. The algorithm described in Appendix A of RFC 6126 MAY be used.

2.2. Non-requirements

NR1: a Homenet implementation of Babel MAY perform route selection by applying hysteresis to route metrics, as suggested in Section 3.6 of RFC 6126 and described in detail in Section III.E of [BABEL-RTT]. However, it MAY simply pick the route with the smallest metric.

NR2: a Homenet implementation of Babel MAY include support for other extensions to the protocol, as long as they are known to interoperate with both the core protocol and source-specific routing.

3. Acknowledgments

4. References

4.1. Normative References

[BABEL-SS] Boutier, M. and J. Chroboczek, "Source-Specific Routing in Babel", Internet-Draft draft-boutier-babel-source-specific-01, January 2015.
[RFC6126] Chroboczek, J., "The Babel Routing Protocol", RFC 6126, February 2011.
[RFC7298] Ovsienko, D., "Babel Hashed Message Authentication Code (HMAC) Cryptographic Authentication", RFC 7298, July 2014.
[RFC7557] Chroboczek, J., "Extension Mechanism for the Babel Routing Protocol", RFC 7557, May 2015.

4.2. Informative References

[BABEL-RTT] Jonglez, B. and J. Chroboczek, "Delay-based Metric Extension for the Babel Routing Protocol", Internet-Draft draft-jonglez-babel-rtt-extension-01, May 2015.
[BABEL-Z] Chroboczek, J., "Diversity Routing for the Babel Routing Protocol", Internet-Draft draft-chroboczek-babel-diversity-routing-00, July 2014.
[DELAY-BASED] Jonglez, B. and J. Chroboczek, "A delay-based routing metric", March 2014.

Available online from

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

Author's Address

Juliusz Chroboczek PPS, University of Paris-Diderot Case 7014 75205 Paris Cedex 13, France EMail: