[Outages-discussion] [outages] Spectrum/Charter IPv6 connectivity to CloudFlare down in Texas

[Carl Perry]

Sorry for the busted formatting, I'm kind of damned if I do (too my 
HTML) and damned if I don't (variable width fonts) when it comes to 
formatting and mailing lists since I don't use a plain text mail client.

I don't believe this is a CloudFlare issue, it's very much a 
Spectrum/Charter issue. Sadly being a lowly non-business customer of 
both companies I'm not entitled to contact any meaningful support. I 
tried to contact CluodFlare but I am only entitled to community forums. 
I had hoped that raising the issue here would get some engineers at both 
companies to connect.

I've worked around the issue by turning off native IPv6 from Spectrum 
and switching back to my trusty old HE TunnelBroker IPv6 link, since it 
seems from comments here and elsewhere that trying to get anyone at 
Spectrum/Charter to care is a lost cause. Everything works as expected, 
thus reinforcing that it's a Spectrum/Charter issue.

   -Carl

On 4/20/23 05:22, Jeremy Chadwick wrote:
> (Moving to -discussion because there's nothing concrete in what I'm
> about to say, i.e. nothing worth waking people up for.)
>
> 1. Your mtrs have lost their monospace/whitespace formatting for
> whatever reason, making them difficult to read.
>
> 2. Your IPv6 mtr looks like it indicates POSSIBLE packet loss starting
> at hop #4 and seems to trickle down through hops #5/6/7.  I can't be
> 100% certain the loss is real (it could be ICMP deprio on Charter's
> routers, but only for IPv6?!) because I have not seen what a working v6
> mtr from you which uses the same routers/path.  If it IS real loss, then
> the problem is much more likely within Spectrum/Charter's network, but I
> can't say that with absolute certainty, leading me to:
>
> 2. You have no return-path mtr for either v4 or v6, so you only are able
> to see 50% of the entire picture.  Asymmetric routing is commonplace
> these days, which is why you need it from both directions.
>
> If you really and absolutely think this is a CloudFlare problem (I am
> not sold on that given the above two points), then we continue with:
>
> 3. Based on 141.101.74.104 in your v4 mtr, it looks like
> Spectrum/Charter has a peering agreement with CloudFlare.
>
> 4. CloudFlare does not offer a public looking glass, but they do offer
> an HTTP API-based traceroute, though it is sub-par in quality and kind
> of bizarre, not to mention I don't know if it supports v6:
> https://blog.clucas.fr/2021/11/18/traceroute-from-cloudflare-without-looking-glass/
>
> Given items #3/4, have you tried reaching out to CloudFlare for a
> return-path mtr back to whatever your v6 source IP is?
>
> Their contact information is public: https://www.peeringdb.com/net/4224
>