netdev - Re: [PATCH v5 0/2] Make neighbor eviction controllable by userspace

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Message-ID: <944f6c2e-bb84-0dfd-b411-1ddefeddb78e@gmail.com>
Date:   Thu, 21 Oct 2021 16:09:39 -0600
From:   David Ahern <dsahern@...il.com>
To:     James Prestwood <prestwoj@...il.com>, netdev@...r.kernel.org
Cc:     "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Jonathan Corbet <corbet@....net>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        David Ahern <dsahern@...nel.org>,
        Roopa Prabhu <roopa@...dia.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Vladimir Oltean <vladimir.oltean@....com>,
        Ido Schimmel <idosch@...dia.com>,
        Nikolay Aleksandrov <nikolay@...dia.com>,
        Chinmay Agarwal <chinagar@...eaurora.org>,
        Yajun Deng <yajun.deng@...ux.dev>,
        Tong Zhu <zhutong@...zon.com>,
        Johannes Berg <johannes@...solutions.net>,
        Jouni Malinen <jouni@...eaurora.org>
Subject: Re: [PATCH v5 0/2] Make neighbor eviction controllable by userspace

On 10/21/21 3:59 PM, James Prestwood wrote:
> So the test itself is pretty simple. The part I'm unsure about is how
> you actually set the carrier state from userspace. I see "ip link set
> <dev> carrier {on,off}" but this reports not supported for veths,
> wlans, and eth interfaces I have tried. AFAIK the driver controls the
> carrier state. Maybe some drivers do support this?
> 
> Is there a way to set the carrier state that you, or anyone is aware
> of?

with veth pairs, if you set one down the other goes into no-carrier mode

make veth0 the one you are validating and put veth1 in a namespace
called testing. Then 'ip -netns testing li set veth1 down' put veth0 in
NO_CARRIER