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.
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 p...@jakma.org @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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