Just to clarify a bit: Before we can go to such low timers we need to put in place a patch that does something like this:
https://github.com/CumulusNetworks/quagga/commit/cb1faec92248549307ffcfd93b24713d339cb8b0 Then we can safely add in whatever MRAI timers we want. As such I intend to take these two MRAI patches and insert them into the take-X stream after this above patch is ported over. donald On Tue, Dec 8, 2015 at 7:59 AM, Daniel Walton <[email protected]> wrote: > > > 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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