4 ms·
Yes, the receiving webserver will get the IP with the HTTP GET, but it's mostly too late to be useful for serving users from a server with minimal latency. The
by cyounkins 5y ago
Yes, the receiving webserver will get the IP with the HTTP GET, but it's mostly too late to be useful for serving users from a server with minimal latency.
The EDNS client subnet feature reveals the clients subnet (but not entire IP) to the nameserver that answers the DNS query, which is then cached by Cloudflare/Google. This allows the nameserver to do geolocation at the DNS stage and direct the end user to a server with minimal latency.
Without EDNS client subnet, you could get the IP for an archive.is frontend in a different continent and have a slow site experience. While the frontend server will get your IP, it's too late to do much about it under normal circumstances. An HTTP redirect would cost time, and you'd have to have different domains for each data center/region which is one thing you can avoid with the client subnet feature to start with.
- CameronNemo 5y agoFrankly they (archive.is) wouldn't have this issue if they used BGP anycast. DNS was never designed to facilitate regional load balancing.
- NickNameNick 5y agoI thought anycast wasn't reliable for TCP sessions? You can serve UDP services (eg DNS) by anycast, but if you hosted a tcp service, there's no guarantee the same server would receive consecutive packets from the tcp stream
- CameronNemo 5y agoIt is rarely an issue in practice. There are workarounds to minimize connection resets. Using ECMP hashing on routers and a tiered load balancing topology are important. https://vincent.bernat.ch/en/blog/2018-multi-tier-loadbalancer https://vincent.bernat.ch/en/blog/2018-multi-tier-loadbalanc... https://blog.cloudflare.com/high-availability-load-balancers-with-maglev/ https://blog.cloudflare.com/high-availability-load-balancers... https://engineering.linkedin.com/network-performance/tcp-over-ip-anycast-pipe-dream-or-reality https://engineering.linkedin.com/network-performance/tcp-ove...
- sterlind 5y agoSeems like LinkedIn had to do some finessing and still couldn't go with global anycast. How do CDNs work without controlling DNS resolution by source subnet?
- CameronNemo 5y agoPresumably a CDN has better and more direct peerings with ISPs than LinkedIn, or admittedly archive.is.
- diroussel 5y agoCloudflare uses any cast, and they deal with it by making every external node able to handle every public IP that they have. If packets in a TCP stream end up going to different nodes, then they deal with that in their infrastructure.