|
North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: [NANOG] Microsoft.com PMTUD black hole?
Iljitsch van Beijnum wrote: > The problem is in the direction from M$ to you, so you can't fix that > from your end. I wonder if they've installed SP3 on their servers... Ah, you are right. I re-read the section on black-hole detection in http://technet.microsoft.com/en-us/library/bb878081.aspx more closely this time, and found that, yes, it only helps if the host trying to send the large packets has the feature enabled: "When PMTU black hole router detection is enabled, TCP tries to send segments with the DF flag set to 0 after several retransmissions of a segment are not acknowledged. If a segment with the DF flag set to 0 is acknowledged, the MSS is decreased and the DF flag is set to 1 in subsequent segments on the connection. Enabling PMTU black hole detection increases the maximum number of retransmissions that are performed for a given segment, and therefore has an effect on overall performance." I for some reason interpreted the advertisement of the black hole detection feature as being a help to clients impacted by the inability of the server to perform PMTUD. -- Nathan Anderson First Step Internet, LLC [email protected] _______________________________________________ NANOG mailing list [email protected] http://mailman.nanog.org/mailman/listinfo/nanog
|