Yep, Virgin Media did this in the UK and messed it up badly. Every day at 6pm YouTube would stop working until the following morning.

It appeared to work by inspecting DNS packets and replying with overrides if necessary. I didn’t like it but I could understand that.

What I did not agree with was the fact that this also happened for other DNS services. Google DNS and OpenDNS both experienced the same issue, as did a few other “famous” DNS providers. Random little ones wouldn’t return the caching servers, and also enabling encrypted DNS for Google/OpenDNS would stop it happening too. I’m fairly sure it was some badly thought out deep packet inspection.

Again, it's probably _not_ Virgin's fault or responsibility. Capacity planning is handled by Google directly.

Also, I think that virtually every ISP with more than a few tens of thousands users is hosting a GGC instance nowadays (and a Netflix OpenCache, etc. etc.).

Nowadays, the vast majority of the transit&peering of ISPs is not going to the Internet, but to a few racks of local caching servers managed by OTT operators.

Bandwidth-wise, at least in prime time, the Internet is much less connected/realtime than people think :)

I would suggest that the deep packet inspection is Virgin's fault. Perhaps it was Google under provisioning the CDN inside VM's network, but I would suggest that's also probably Virgin's fault in part, as they will likely have more network information available to them that may have suggested network congestion, but that was not acted upon.