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AWS's offering which is software based - http://aws.amazon.com/elasticloadbalancing/ http://aws.amazon.com/elasticloadbalancing/

• Xorlev 12y ago
  Doesn't work for datacenters. Also is implemented with round-robin DNS to nodes (1-N, check X-Forwarded-For) in each AZ, which then handle balancing. Also worth noting that unless you turn on cross-region balancing, if an AZ doesn't have a node in it and the RR DNS points them at that AZ, they'll be turned away. Additionally, without it you need to scale by multiples of AZs you run in otherwise you'll have unbalanced traffic. On another note, I've always been curious if they're just abstractions around HAproxy at the per-node level.
  • skyebook 12y ago
    FWIW, Amazon recently added the ability to load balance across AZ's (Still round-robin though)
    • Xorlev 12y ago
      Very true. Cross-AZ load balancing works quite well. I believe Amazon has said it's RR across the servers with the least connections, but degenerates to a simple RR without many nodes per AZ.