[c-nsp] BGP (VPNv4) flapping every 3minutes

CiscoNSP List cisconsp_list at hotmail.com
Sun Dec 21 04:38:00 EST 2014

> On Sun, Dec 21, 2014 at 10:28:30AM +1100, CiscoNSP List wrote:
> > ok - Ive after a bit of searching, looks like it is caused by mtu...Ive added " transport path-mtu-discovery disable" to one of the RR's on .219, and it's been up for 7+min....looks like this was the issue..
> This hints at a MTU problem in your network, and the proper fix is to
> fix the MTU problem, not add config to the RR to work around it.

Thanks Gert - It's because we are purchasing inter-pop links from other carriers(And there supported MTU's varies dramatically)...in this instance our PE's "agreed" on 1900'odd MSS, but we were only able to get ~1544.....On the links we control, it's all 9100.....and we tweak as needed with carrier supplied links.


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