Incremental Deployment of HNCP and IGPs in home networks
draft-barth-homenet-incremental-deployment-00

Abstract

This document describes an incremental approach towards deploying HNCP and routing protocols in home networks. Its aim is to provide a minimal, forward-compatible transitional extension to HNCP to promote testing, deployment and adoption of homenet technology while the IGP decision and standardization process is not yet finalized.

Status of This Memo

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This Internet-Draft will expire on September 10, 2015.

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Table of Contents

• 1. Introduction
• 2. Implementation Requirements for Incremental Deployments
• 3. Incremental Connectivity Algorithm
• 4. Security Considerations
• 5. IANA Considerations
• 6. Normative references
• Appendix A. Acknowledgements
• Author's Address

1. Introduction

While it is expected that the average number of routers and their hardware and software capabilities in a typical home network will grow over time, this trend has historically been gradual. Thus it can be expected that in the near future there will most likely be not more than a handful of routers in a home and their capabilities for operating in a fully-routed mode are limited.

It is also hard to predict which types of other networks the homenet technology will be used in and what attributes these networks will have (e.g. number of routers, links, link-types, topologies, suitable methods for detecting link-layer status and deriving metric). Furthermore the standardization of autoconfiguring and source-dest-routing capable protocols is not expected to be finalized soon and there is currently a shortage of widely testable or deployable implementations fulfilling these criteria.

These issues and a general lack of consensus over an all-purpose routing protocol support a transitional forward-compatible extension to HNCP [I-D.ietf-homenet-hncp] implementations in order to advance homenet progress and to promote adoption. This draft describes a solution sufficient for small networks allowing gradual adoption of homenet principles into existing networks while ensuring an easy transition to a future standardized version.

2. Implementation Requirements for Incremental Deployments

Each homenet router runs an incremental connectivity algorithm at all times on each network interface it is running HNCP on and can optionally additionally run one or more routing protocols.

A router running a routing protocol alongside the incremental connectivity algorithm must strictly prefer all routes of the routing protocol over all routes generated by the incremental connectivity algorithm, except for those having destinations not already known to the routing protocol but that lie within one of the designated prefixes of the homenet (i.e. prefixes assigned by a homenet router that does not speak the respective routing protocol). In case of routers running more than one routing protocol alongside the incremental connectivity algorithm, all such routers in the homenet ensure that in doing so they do not cause routing loops, e.g. by agreeing upon a network-wide order in which routes of the protocols are considered.

3. Incremental Connectivity Algorithm

This algorithm is designed to provide connectivity in small home networks that would not benefit from exploiting link characteristics or metrics. It is intentionally kept simple to require no additional TLV-information by reusing existing topology and address assignment information provided by HNCP and only requires minimal implementation overhead.

Each homenet router traverses the HNCP neighbor graph using a breadth-first search starting with its own node's immediate neighbors. Neighbors of a node are traversed in ascending order of their node identifier. During traversal the router determines the path to each other router (R), the next-hop neighbor N(R) and the number of hops to it D(R). The router then creates routes based on the following rules:

This process is repeated every time the router detects a change in the neighbor graph or prefix assignment information in the network.

4. Security Considerations

The mechanism described in this document is based on HNCP, thus security considerations for this document are already covered by [I-D.ietf-homenet-hncp].

5. IANA Considerations

This document has no actions for IANA.

6. Normative references

Appendix A. Acknowledgements

Thanks to Pierre Pfister and Markus Stenberg for comments and suggestions.

Author's Address