netdev - Re: tcp_tw_recycle broken?

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Message-ID: <f9be06770811150747l574badc1l8d509baae4f81ac5@mail.gmail.com>
Date:	Sat, 15 Nov 2008 10:47:10 -0500
From:	"Karl Pickett" <karl.pickett@...il.com>
To:	"Andi Kleen" <andi@...stfloor.org>
Cc:	linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: tcp_tw_recycle broken?

On Sat, Nov 15, 2008 at 8:09 AM, Andi Kleen <andi@...stfloor.org> wrote:
> "Karl Pickett" <karl.pickett@...il.com> writes:
>>
>> May I just confirm.. is tcp_tw_reuse NOT dependent on receiving timestamps?
>
> The big problem is that both are incompatible with NAT. So if you
> ever talk to any NATed clients don't use it.
>
> -Andi
>
> --
> ak@...ux.intel.com
>

Hmph.  Running the test again - after getting a little sleep -
timestamps do indeed determine if tw_reuse/recyle work.  I must not
have let all the tw buckets expire before changing my timestamp
settings last night.

Since
A. I don't want to rely on arbitrary web servers having timestamps
B. People say it breaks NAT for clients, and the settings are global only,

I will just set TCP_TIMEWAIT_LEN to 10 seconds and call it a day.
Sure would be nice if it was a tunable, so only the most heavily
loaded customers could set it...

-- 
Karl Pickett
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