Thanks for guidance everyone!
Appreciate it. And yes, I can see another thread running on discussion about /48 - I am listening silently about it. Multiple AS doing anycasting was little concern for me, but now seems good since I can see everyone's suggestion to use single own ASN for anycasting. On Fri, Mar 9, 2012 at 3:25 PM, Pete Carah <p...@altadena.net> wrote: > On 03/09/2012 01:34 AM, Elmar K. Bins wrote: > > Re Bill, > > > > wo...@pch.net (Bill Woodcock) wrote: > > > >>> Well, let's say, using Quagga/BIRD might not really be best practice > for > >>> everybody... (e.g., *we* are using Cisco equipment for this) > >> How does your Cisco know whether an adjacent nameserver is heavily > loaded, and adjust its BGP announcements accordingly? > > It doesn't have to. > > > > I don't know how you guys do it, but we take great care to > > keep min. 70% overhead capacity during standard operation. > > > My point had to do with resilience in the face of hardware/OS/software > failures in the box providing the > service. Bill's has more to do with resilience in the face of other > network events (e.g. the upstream for one > of the boxes has a DDOS; you cannot reasonably provide enough excess > capacity to handle that...) Neither of these is addressed by using a > separate router to announce the server's anycast route. (unless somehow > the Cisco is providing the anycasted service, which would address my > concern but still not Bill's.) > > Also, Bill is probably talking root (or bigger public) servers whose > load comes from "off-site"; the average load characteristics for those > are well known but there can be extremes that would be hard to plan for > (hint - operating at 30% isn't really good enough, probably not 10% > either. Bill (and the other Bill) have pretty good stats for this that > I've only glanced at...) And it is easy to see where one of the > extremes might hit only one or two of the anycast instances. He implies > having the instances talking to each other in background to adjust bgp > announcements to maybe help level things. Fortunately at least for the > root servers, the redundancy is at two levels and anycast is only one of > them. > > -- Pete > > > -- Anurag Bhatia anuragbhatia.com or simply - http://[2001:470:26:78f::5] if you are on IPv6 connected network! Twitter: @anurag_bhatia <https://twitter.com/#!/anurag_bhatia> Linkedin: http://linkedin.anuragbhatia.com
