[squid-users] New Squid prefers IPv4

[Antony Stone]

On Monday 05 February 2024 at 17:32:51, Rob van der Putten wrote:

> Hi there
> 
> 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, 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.

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.


Antony.

-- 
I want to build a machine that will be proud of me.

 - Danny Hillis, creator of The Connection Machine

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