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We had the same experience at Quantcast. Better results with anycast within continents, and DNS to distribute a per-continent anycast addresses. Some know-it-a
by paulsutter 11y ago
We had the same experience at Quantcast. Better results with anycast within continents, and DNS to distribute a per-continent anycast addresses.
Some know-it-all busybodies like to proclaim that anycast can't work for TCP because the route can change during the session, but the reality is that:
- route changes are infrequent
- individual sessions are typically much shorter than route change intervals
- we never experienced proposed problems with sustained route flapping
- route changes are readily detected and handled as (rare) dead connections. The nicest bit is that transferred live connections can get rejected and closed immediately by the new server allowing for rapid recovery (unlike DNS changes which leaves things hanging for a long time).
We had extremely fast datacenter failover using anycast (100% of traffic moved as soon as 5 seconds). Contrasted to the minutes-to-hours nightmare delays that characterize DNS failover. (The DNS time-to-live is an advisory at best, and outright ignored by many clients)
It's too bad more hosting providers don't allow route announcements.
- sspies 11y agoI can fully agree with your experience using DNS failover vs anycast failover. Made a video of how I implemented anycast https://www.youtube.com/watch?v=tsXpQHi7Udo https://www.youtube.com/watch?v=tsXpQHi7Udo
- _ao789 11y agoInteresting video, thanks for sharing
- federico3 11y ago> individual sessions are typically much shorter than route change intervals True for web traffic, not true for large file transfers, many multiplayer games, VPNs. > live connections can get rejected and closed immediately by the new server allowing for rapid recovery ...if the client protocol allows recovery.
- dsl 11y agoSame here. The only people dismissing TCP anycast at this point are folks who haven't been running anycast deployments. It also helps to respond to DNS with multiple VIPs within your anycast /24. Browser retry logic is pretty nifty and solves most of the real world problems.
- riteshm 11y agoGlad to hear that Paul! This is Ritesh, author of the LinkedIn article. Lets chat offline. I am curious to see if you guys faced some issues that we are seeing.