On Tue, Dec 8, 2015 at 4:40 AM, Paul Jakma <[email protected]> wrote: > On Mon, 7 Dec 2015, Daniel Walton wrote: > > FWIW IOS has used 0 for iBGP and 5 for eBGP since ~2004. We (cisco at the >> time) never had any complaints when we changed to these values (they were >> both 30s before). The only reason we didn't do 0 for eBGP was because >> dampening was still used a fair amount back then (not so much now). >> > > With the MRAIs set to 0 you can get some bursts of path hunting but they >> tend to be short lived because bgp ends up converging so fast (sub-second >> is typical). Given the lack of complaints when the iBGP timer was changed >> to 0, I don't think increased path hunting is much of a concern. Path >> hunting is worse as meshiness increases and an iBGP core tends to be more >> meshy and eBGP connections. I think we could use 0 for both without any >> path hunting issues. >> > > Interesting. > > I'd probably keep eBGP !0, just for the sake of being conservative for > now. BGP can produce /many/ rounds of messages, and the literature shows > that as you decrease the MRAI past the optimum the number of messages and > go toward 0 the number of messages increases very quickly again (but > linearly). Even just 1s, just to avoid causing bad storms somewhere between > different ASes. > > I can get on board with 0 for iBGP and 1s for eBGP :) Maybe someday we can look into this draft as a means of making it 0 for ebgp:
https://tools.ietf.org/html/draft-keyupate-bgp-rcn-00 Daniel > Path hunting is indeed made much more worse by high MRAIs. > > iBGP, sure go to 0. Same operator, and the network will be smaller in size > compared to the Internet. > > Important bit: we're all agreed the standards specified values and > Quagga's current defaults are _way_ too high. ;) > > regards, > -- > Paul Jakma [email protected] @pjakma Key ID: 64A2FF6A > Fortune: > Romeo wasn't bilked in a day. > -- Walt Kelly, "Ten Ever-Lovin' Blue-Eyed Years With Pogo" >
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