SOLVED! The cause of puzzling TCP (eg. WHOIS) connection failures with some InterNIC.net hosts

Tue Nov 24 16:07:40 UTC 1998

On Fri, Nov 20, 1998 at 04:25:11PM -0500, Greg A. Woods wrote:
> The problem has to do with the failure of a host to fragment larger
> packets on demand (i.e. when the other host sends an ICMP "needs frag"
> notification).  This may be because the ICMP packet never gets through
> (perhaps someone who didn't understand TCP/IP and ICMP and everything
> else related implemented a filter on all "abnormal" ICMP packets); or it
> may be because the receiving host doesn't understand the ICMP "needs
> frag" request (and also doesn't implement path MTU discovery, or have I
> got that backwards?).
> 
> No matter what the problem really is, I'm sure a *lot* of people would
> be much happier if this problem were fixed, specifically for the WHOIS
> service (though I've also had troubles receiving HTTP too).  I got quite
> a few replies about similar experiences when I first posted about this
> on NANOG recently.

Thanks Greg for the good information.

The InterNIC load balancers (BigIP made by F5 Labs) do have a problem with
path MTU discovery. We have taken a short term fix of turning off path MTU
discovery on the hosts behind BigIP until F5 issues a fix.

Regards,
Mark

--

Mark Kosters     markk at internic.net      InterNIC Registration Services
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