Subject: Re: [RFC PATCH v3 net-next] net: ipv6: Add a sysctl to make optimistic addresses useful candidates

From: Nicolas Dichtel <[email-masked]>
Date: Thu, 23 Oct 2014 17:12:50 +0200

Le 23/10/2014 11:59, Erik Kline a écrit :
> Add a sysctl that causes an interface's optimistic addresses
> to be considered equivalent to other non-deprecated addresses
> for source address selection purposes.  Preferred addresses
> will still take precedence over optimistic addresses, subject
> to other ranking in the source address selection algorithm.
>
> This is useful where different interfaces are connected to
> different networks from different ISPs (e.g., a cell network
> and a home wifi network).
>
> The current behaviour complies with RFC 3484/6724, and it
> makes sense if the host has only one interface, or has
> multiple interfaces on the same network (same or cooperating
> administrative domain(s), but not in the multiple distinct
> networks case.
>
> For example, if a mobile device has an IPv6 address on an LTE
> network and then connects to IPv6-enabled wifi, while the wifi
> IPv6 address is undergoing DAD, IPv6 connections will try use
> the wifi default route with the LTE IPv6 address, and will get
> stuck until they time out.
>
> Also, because optimistic nodes can receive frames, issue
> an RTM_NEWADDR as soon as DAD starts.  If DAD fails, a separate
> RTM_DELADDR is always sent.
>
> Also: add an entry in ip-sysctl.txt for optimistic_dad.
>
> Signed-off-by: Erik Kline <[email-masked]>
I agree with the principle of the patch. This option is useful.

Thank you,
Nicolas