RE: IPv6 Performance (was Re: IPv4 Pricing)

[Gary Sparkes via NANOG <nanog () lists nanog org>]

Indeed, that reeks of an upstream routing issue somewhere, you're not taking the same physical path for V6 as you are 
V4. 

I find myself experiencing the opposite sometimes, though the v4 path was fixed relatively recently, my home ISP 
upstreams for v4 used to be cogent and sprint, so except for tunneling forcing an early exit, most of my V4 traffic 
went MD->NY first, then back down to PA. 

I had to look long and hard to find an earlier off-ramp for my IPv6 tunnels. Fortunately I was able to path out a 
provider that just went MD->PA->VA ..... though, as said, it's a lot better now (AS27364 for the curious - great ISP 
except the lack of v6 on resi connections.... I've had to tunnel v6 access - which is a hard requirement for me given 
how much v6 resources are in play - since 2009)

-----Original Message-----
From: Josh Luthman via NANOG <nanog () lists nanog org> 
Sent: Monday, December 1, 2025 5:06 PM
To: North American Network Operators Group <nanog () lists nanog org>
Cc: Bryan Fields <Bryan () bryanfields net>; Josh Luthman <josh () imaginenetworksllc com>
Subject: Re: IPv6 Performance (was Re: IPv4 Pricing)

I think that's pretty subjective.  Everything I read says ipv6 is faster.

This comes from someone not doing any v6 in practice and only reads articles and reports.

On Mon, Dec 1, 2025, 4:44 PM Bryan Fields via NANOG <nanog () lists nanog org>
wrote:

> On 12/1/25 14:22, Jared Mauch via NANOG wrote:
>
> > I find myself having to tether off their networks when I’m on IPv4 
> > only networks to access things like my hypervisors and other assets 
> > that are IPv6-only because they have superior networking these days.
>
> While I'll agree v6 is easy and should be deployed I have to take 
> issue with the current as-built being superior.
>
> At least once or twice a month I'm downloading something and will find 
> the
> IPv4 to transfer significantly faster.  Case in point, I downloaded 
> the proxmox iso yesterday to a colo server with 50g uplinks.  It 
> loafed at 2.4 mbytes/s using default wget, which of course preferred 
> ipv6.  Adding -4 to wget made that shoot up to 80 mbytes/s.
>
> This is ipv6 behavior I've seen time and time again.  I'm unsure where 
> problems like these lie in the network, other than it's not mine or my 
> peers.
> I've seen the same issues with v6 paths to the same server bounce 
> around the west coast and back, whilst IPv4 is 6 hops and 12 ms away.
>
> This is exactly the sort of thing that holds IPv6 back by giving it a 
> bad name.
> --
> Bryan Fields
>
> 727-409-1194 - Voice
> http://bryanfields.net
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