Re: A common problem with SLAAC in "renumbering" scenarios

Sander Steffann <sander@steffann.nl> Thu, 31 January 2019 12:04 UTC

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From: Sander Steffann <sander@steffann.nl>
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Subject: Re: A common problem with SLAAC in "renumbering" scenarios
Date: Thu, 31 Jan 2019 13:04:16 +0100
In-Reply-To: <alpine.DEB.2.20.1901311236320.5601@uplift.swm.pp.se>
Cc: Fernando Gont <fgont@si6networks.com>, IPv6 Operations <v6ops@ietf.org>, "6man@ietf.org" <6man@ietf.org>
To: Mikael Abrahamsson <swmike@swm.pp.se>
References: <60fabe4b-fd76-4b35-08d3-09adce43dd71@si6networks.com> <alpine.DEB.2.20.1901311236320.5601@uplift.swm.pp.se>
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> "   o  A CPE MUST record, on stable storage, the list of prefixes being
>      advertised on each LAN segment."
> 
> This is not always doable as some devices have very small flash with no write-leveling, so doing this generally might ruin the flash cells on some devices. This above requirement will drive cost, especially in the low end market of HGWs.

A flash cell is at least capable of 1000 to 3000 erase/write cycles. Even if the prefix would change every single day that gives a lifetime of 3 to 9 years. And prefixes shouldn't change that often anyway. When looking at more realistic estimates line a change on average once a week you'l get to 20 years. Seems more than enough for low end extra cheap devices. I don't see this driving cost up, except for spending a few hours on properly engineering this.

Cheers,
Sander