[squid-users] WARNING: Tos value ... adjusted

[Amos Jeffries]

On 24/04/2015 6:26 a.m., Nick Rogers wrote:
> On Wed, Apr 22, 2015 at 10:35 PM, Amos Jeffries <squid3 at treenet.co.nz>
> wrote:
> 
>> On 23/04/2015 9:14 a.m., Nick Rogers wrote:
>>> After upgrading from 3.4.x to 3.5.x, I've noticed a new error message
>> with
>>> my squid configuration. Apparently squid 3.5 no longer allows setting the
>>> two lower-most ECN bits of the ToS byte.
>>
>> Allowing it and leaving it up to admin was causing too much confusion
>> over mysteriously dropped traffic.
>>
>> Attempts to bit-shift values were not backward compatible. So instead we
>> opted to take a bitmask hex value as the TOS parameter and explicitly
>> forbid with warning the ECN bits being set in that mask.
>>
> 
> Can you elaborate on how you would bit-shift the values to still use the
> ECN field and not cause mysterious problems. For example, using ECN bits of
> 00 and 11, but not 01 or 10?

Sure. We experimented with taking the config value N and using TOS value
(N<<2) for IPv4 and N for IPv6. Didn't work out well.

Amos