Re: [tsvwg] Switch testing at 25G with ECN --SCE Draft
"Rodney W. Grimes" <freebsd@gndrsh.dnsmgr.net> Fri, 09 August 2019 23:44 UTC
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From: "Rodney W. Grimes" <freebsd@gndrsh.dnsmgr.net>
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To: John Leslie <john@jlc.net>
Date: Fri, 09 Aug 2019 16:44:41 -0700
CC: Jonathan Morton <chromatix99@gmail.com>, tsvwg@ietf.org
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Subject: Re: [tsvwg] Switch testing at 25G with ECN --SCE Draft
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> Jonathan Morton <chromatix99@gmail.com> wrote: > >> On 7 Aug, 2019, at 10:47 am, <Ruediger.Geib@telekom.de> <Ruediger.Geib@telekom.de> wrote: > >> > >> I think to recall that a colleague noticed random initial packet drop > >> bursts with IPERF3 too (and stopped using it). > > > > These are almost certainly associated with slow-start, whose > > exponential growth is that much harder to control than subsequent > > linear growth. > > It's kind of silly that each new TCP connection starts with the > assumption that it knows absolutely nothing about the likely capacity > and congestion of the route to its destination. > > Can't we do something to fix this? Some end systems do infact do something about this, they cache information about there last connection on that route, other ends systems have more complicated stuff. I am not positive as to the current state of which data is still maintained by a BSD kernel, but a "route" has storage for: route -n get 192.168.114.114 route to: 192.168.114.114 destination: 192.168.114.114 interface: lnc1 flags: <UP,HOST,DONE,LLINFO,WASCLONED> recvpipe sendpipe ssthresh rtt,msec rttvar hopcount mtu expire 0 0 0 0 0 0 1500 954 7 things, plus an expire timer. There is nothing in the protocols that specify this, and imho there should never be anything in the protocols that specify the use or non use of this type of solution. I believe there is at least one vendor that sends the last known download bandwidth on the connection request to there servers in a higher layer protocol and use that information to pace the initial packets on a new connection until new data can be obtained. > -- > John Leslie <john@jlc.net> -- Rod Grimes rgrimes@freebsd.org
- [tsvwg] Switch testing at 25G with ECN --SCE Draft Scaglione, Giuseppe
- Re: [tsvwg] Switch testing at 25G with ECN --SCE … Ruediger.Geib
- Re: [tsvwg] Switch testing at 25G with ECN --SCE … Jonathan Morton
- Re: [tsvwg] Switch testing at 25G with ECN --SCE … Greg White
- Re: [tsvwg] Switch testing at 25G with ECN --SCE … Rodney W. Grimes
- Re: [tsvwg] Switch testing at 25G with ECN --SCE … Scaglione, Giuseppe
- Re: [tsvwg] Switch testing at 25G with ECN --SCE … Greg White
- Re: [tsvwg] Switch testing at 25G with ECN --SCE … Scaglione, Giuseppe
- Re: [tsvwg] Switch testing at 25G with ECN --SCE … Jonathan Morton
- Re: [tsvwg] Switch testing at 25G with ECN --SCE … Greg White
- Re: [tsvwg] Switch testing at 25G with ECN --SCE … Scaglione, Giuseppe
- Re: [tsvwg] Switch testing at 25G with ECN --SCE … Greg White
- Re: [tsvwg] Switch testing at 25G with ECN --SCE … Jonathan Morton
- Re: [tsvwg] Switch testing at 25G with ECN --SCE … John Leslie
- Re: [tsvwg] Switch testing at 25G with ECN --SCE … Rodney W. Grimes
- Re: [tsvwg] Switch testing at 25G with ECN --SCE … Rodney W. Grimes
- Re: [tsvwg] Switch testing at 25G with ECN --SCE … Dave Taht
- Re: [tsvwg] Switch testing at 25G with ECN --SCE … Jonathan Morton
- Re: [tsvwg] Switch testing at 25G with ECN --SCE … Wesley Eddy
- Re: [tsvwg] Switch testing at 25G with ECN --SCE … Black, David
- Re: [tsvwg] Switch testing at 25G with ECN --SCE … Black, David
- Re: [tsvwg] Switch testing at 25G with ECN --SCE … Scaglione, Giuseppe
- Re: [tsvwg] Switch testing at 25G with ECN --SCE … Ruediger.Geib
- Re: [tsvwg] Switch testing at 25G with ECN --SCE … Gorry Fairhurst
- Re: [tsvwg] Switch testing at 25G with ECN --SCE … Rodney W. Grimes
- Re: [tsvwg] Switch testing at 25G with ECN --SCE … Gorry Fairhurst