[homenet] IS-IS metric mechanism and implementation (was Re: Info about IS-IS demo from Bits N Bites Prague)

[Mikael Abrahamsson <[e-mail]>]

Hi,

I just want to change the subject of this so that people who are 
interested in this topic doesn't miss it.

On Thu, 17 Sep 2015, Christian Franke wrote:

> Hello all,
>
> since there have been some inquiries about different aspects of the demo
> that NetDEF showed at the bits N bites in Prague, I decided to provide a
> more detailed description here on the list.
>
> We showed a home network running HNCP and two different implementations
> of IS-IS interoperating with each other, at the high level the demo showed:
>
> - IS-IS for Homenet (IPv6 & IPv4)
> - Transport: both L2 & IPv6 (Link-Local)
> - Point-to-Multi-Point or Broadcast over L2 or IPv6
> - Dynamic IS-IS Route Metric updating based on WiFi QualityInfo about
> IS-IS demo from Bits N Bites Prague
> - HNCP IPv6 Prefix Delegation
> - SRC / DEST Routing
> - IS-IS Auto-Configuration
>
> Both code bases implemented the following extensions on top of standard
> IS-IS:
>
> - draft-franke-isis-over-ipv6
> - draft-baker-ipv6-isis-dst-src-routing
> - draft-lamparter-isis-p2mp
> - draft-franke-isis-over-ipv6
> - dynamic metric support (see below)
>
> For more information for the first four bullet points, please refer to
> the drafts.
>
> There is currently no draft on the dynamic metric support, since this
> feature does not change the IS-IS protocol. Therefore, a short
> description is following.
>
> For the dynamic metrics support, we implemented a small daemon called
> etxrd which provides metric information from the 802.11 layer. The
> information is gathered using OpenWRT's libiwinfo, on our platform using
> nl80211. We have a patch for libiwinfo that allows us to query the
> estimated tx rate from the wifi stack, this value is suitable as a
> metric for routing purposes. However that patch has not been in a
> release yet, so to support running our code on the current standard
> OpenWRT system, we rely on SNR as a metric for now. This provides some
> information, but is suboptimal.
>
> The daemon currently only provides metrics for the wifi side. We use a
> fixed (better) metric for wired connections.
>
> Just to clarify, that daemon is not specific to IS-IS, and it does not
> need IS-IS to run. It just provides metric information about known
> 802.11 neighbors that can be consumed by any interested party, e.g.
> other routing protocols, without requiring any modification on the
> daemon side.
>
> In our use case, IS-IS subscribes to the provided information and uses
> it to adjust metrics for the neighbors. These are standard IS-IS wide
> metrics, although it makes use of the per neighbor metrics available
> with draft-lamparter-isis-p2mp.
>
> Since 802.11 clients/stations only communicate with other stations via
> the access point, they do only have metric information about the access
> point, while the access point has information about all clients. To
> address this, links without metric information (i.e. direct links
> between clients) will not be considered for SPF. Since 802.11 frames
> from clients to clients are relayed by the AP, this actually can reflect
> the metrics better.
>
> ---
>
> The code that was use for the demo is available at the NetDEF git. There
> is a package feed for OpenWRT that allows to build images containing our
> IS-IS version available here:
>
> https://git.netdef.org/projects/OSR/repos/openwrt-isis-hnet/
>
> Instructions for using that feed can be found in the README file.
>
> -Christian
>
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-- 
Mikael Abrahamsson    email: [e-mail]