On Mar 24, 2011, at 1:47 PM, Patrick W. Gilmore wrote: > On Mar 24, 2011, at 3:40 PM, Owen DeLong wrote: >> On Mar 24, 2011, at 12:42 PM, Zaid Ali <z...@zaidali.com> wrote: >> >>> I have seen age old discussions on single AS vs multiple AS for backbone >>> and datacenter design. I am particularly interested in operational >>> challenges for running AS per region e.g. one AS for US, one EU etc or I >>> have heard folks do one AS per DC. I particularly don't see any advantage >>> in doing one AS per region or datacenter since most of the reasons I hear >>> is to reduce the iBGP mesh. I generally prefer one AS and making use of >>> confederation. >>> >>> Zaid >> >> If you have good backbone between the locations, then, it's mostly a matter >> of personal preference. If you have discreet autonomous sites that are not >> connected by internal circuits (not VPNs), then, AS per site is greatly >> preferable. > > We disagree. > > Single AS worldwide is fine with or without a backbone. > Only if you want to make use of ugly ugly BGP hacks on your routers, or, you don't care about Site A being able to hear announcements from Site B.
> Which is "preferable" is up to you, your situation, and your personal tastes. > (I guess one could argue that wasting AS numbers, or polluting the table > with lots of AS numbers is bad or un-ashetically pleasing, but I think you > should do whatever fits your situation anyway.) > I don't see any significant downside to AS number consumption given a 32-bit AS Number space. I do see significant downsides to disabling BGP loop detection. Owen
