On 17/02/2015 01:11 μμ, Mariusz Gronczewski wrote: > On Mon, 16 Feb 2015 12:41:06 +0100, Klavs Klavsen <[email protected]> wrote: > >> As I understand anycast and ECMP (and I only know guys who use it and >> know what they are doing ;) - it needs to be two different routes (ie. >> routers) that are active/active.. ie. multiple location.. but I guess >> one could do it in the same datacenter as well.. >> > > our setup(1 DC): > > * active-active ECMP > * 4 loadbalancers + bird OSPF > * 2 routers + OSPF > * IPs are on loopback interface, added and removed when haproxy service > starts/stops > * OSPF distributes routes to these IPs to routers > * routers route by source IP so same IP always lands on same > loadbalancer > > works pretty well ;) you just have to make sure that when you stop > haproxy (maintenance etc) you also down IPs that haproxy used so routers > stop sending traffic to that node > >
I have a similar setup here with following differences * BGP instead of OSPF * BFD in use for fast removal of prefixes when server/bird/switches are dead * Bonding in use on load balancers * Traffic is coming from multiple locations, local and remote (branches / Internet) * Anycast between DCs -- traffic generated in DC is served locally unless all local LBs are dead -- Traffic generated remotely goes to the nearest DC -- Traffic generated remotely travels over dedicated links/MPLS, from PoPs and branches. MTU path discovery is an issue but we haven't noticed yet happening because remote users are using our global network infrastructure which we control, users from Internet it is a different story, as you can't control Internet:-) A more detailed description of the problem can be found here, https://blog.cloudflare.com/path-mtu-discovery-in-practice/ Cheers, Pavlos
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