Internet DRAFT - draft-barth-homenet-incremental-deployment
draft-barth-homenet-incremental-deployment
Homenet Working Group S. Barth
Internet-Draft
Intended status: Informational March 9, 2015
Expires: September 10, 2015
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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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Implementation Requirements for Incremental Deployments . . . 2
3. Incremental Connectivity Algorithm . . . . . . . . . . . . . 3
4. Security Considerations . . . . . . . . . . . . . . . . . . . 3
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
6. Normative references . . . . . . . . . . . . . . . . . . . . 4
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 4
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 4
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
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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:
+--------------------------------+-----------+------+------+--------+
| Create a route | To | From | Via | Metric |
+--------------------------------+-----------+------+------+--------+
| For each Prefix (A) in an | A | any | N(R) | D(R) |
| Assigned Prefix TLV of any | | | | |
| Router (R) | | | | |
| For each IPv6 prefix (P) in a | ::/0 | P | N(R) | D(R) |
| Delegated Prefix TLV of any | | | | |
| Router (R) | | | | |
| For the first Router (R) | 0.0.0.0/0 | any | N(R) | D(R) |
| traversed that announces an | | | | |
| IPv4 Delegated Prefix TLV | | | | |
+--------------------------------+-----------+------+------+--------+
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].
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5. IANA Considerations
This document has no actions for IANA.
6. Normative references
[I-D.ietf-homenet-hncp]
Stenberg, M., Barth, S., and P. Pfister, "Home Networking
Control Protocol", draft-ietf-homenet-hncp-04 (work in
progress), March 2015.
Appendix A. Acknowledgements
Thanks to Pierre Pfister and Markus Stenberg for comments and
suggestions.
Author's Address
Steven Barth
Halle 06114
Germany
Email: cyrus@openwrt.org
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