[squid-users] New Squid prefers IPv4

[Rob van der Putten]

Hi there


On 05/02/2024 18:32, Antony Stone wrote:

> On Monday 05 February 2024 at 17:32:51, Rob van der Putten wrote:
> 
>>
>> On 05/02/2024 17:16, Dieter Bloms wrote:
>>> On Mon, Feb 05, Rob van der Putten wrote:
>>>> After upgrading Squid from 3 to 5 the percentage of IPv6 reduced from
>>>> 61% to less then 1%.
>>>> Any ideas?
>>>
>>> yes, since squid5 the happy eyeball algorithm as described in rfc 8305
>>> is used.
>>> If your ipv4 connectivity is better than ipv6 than ipv4 is used.
>>
>> I'm not quite sure how this is established. It prefers IPv4 even when
>> the IPv6 ping is slightly smaller.
> 
> I believe ping (ICMP) timings are irrelevant.  The client (squid in this case)
> does a DNS lookup for the hostname's A and AAAA records,

A before AAAA. Bind responds within the same millisecond.

> then makes two
> simultaneous HTTP connections to the server (one IPv4, on IPv6) and whichever
> one responds first *by HTTP* is then regarded as being the best way to route
> traffic thereafter.

I do not see Squid opening two connections simultaneously and then 
closing one. It's just one connection.

> So, if you want to understand how this is doing what it is, I suggest you
> perform a packet capture of HTTP traffic and look at the requests and the
> response timings.


Regards,
Rob