Load Balancing without Load Balancers • Hacker News Board

Re: Load Balancing without Load Balancers

#11

Post by xxdesmus » Wed, Mar 06, 2013, 7:11 PM UTC

23david wrote: post #8

Why not also use software load balancers? I don't see the advantage of going to so much effort to avoid software load balancing. It's neat that you guys got it to work, but I would think that a hybrid system would have more functionality and could better handle degraded performance situations.

A software load balancer is coming soon. Don't worry. The hybrid approach (network + app level intelligence) still has some advantages as well.

Re: Load Balancing without Load Balancers

#12

Post by mnutt » Wed, Mar 06, 2013, 7:12 PM UTC

If a particular server starts to become overloaded, and it appears there is sufficient capacity elsewhere, then just some of the BGP routes can be withdrawn to take some traffic away from the overloaded server

I'd be interested to hear about the mechanism for determining if there is sufficient capacity elsewhere, and how you avoid a cascading failure.

Re: Load Balancing without Load Balancers

#13

Post by spydum » Wed, Mar 06, 2013, 7:47 PM UTC

One thing I always wondered is how session persistence is maintained for things like webapps when trying to host services through anycast. Only idea I can dream up is cookie based and involves each site having internal proxy mappings to each pop in the event a different pop becomes the favored route (paths change all the time, and routers on the internet dont care that you had an established connection).

Re: Load Balancing without Load Balancers

#14

Post by junkilo » Wed, Mar 06, 2013, 7:52 PM UTC

Great writeup! If you offer a global service you are expected to use anycast on the WAN. BGP AS path selection is just as effective whether you use unicast or anycast.