Re: Output Drops on Interface

Thanks.
Yeah, it wasn't the router's fault. At the time I monitored this situation,
latest linux kernel supported, yet did not enable the feature by default.
winxp, which is the most prevalent enterprise workstation os up to this day,
did not have ECN turned on by default either, and neither did the windows
2003 server.
Other *nix flavors, like hpux, tru64, aix, etc. also did not have it on by
default.

And it's very hard to make a case, that so many man days of labor are
required to change TCP/IP stack setting of all OSes of all the machines,
just to save a measily number of packets from an early drop, in comparison
to how many packets are transmitted and/or tail dropped.

2009/4/8 Daniel Kutchin <daniel_at_kutchin.com>

> Pavel,
>
> BTW, your postings are nice.
>
> > I had an ECN in the network for over a year, and NOT ONE
> > SINGLE PACKET was ever ECN Capable, although billions were dropped
> > by WRED
> > across many routers.
>
> It's probably not the router(s)' fault.
>
> The TCP applications winging the routers need to first indicate that
> they're ECN capable, before ECN marking takes place (rfc3168).
>
> Code writer, switch on the ECT bit pleez :-)
>
>
> -
> Daniel
>
>
> -----Original Message-----
> From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of
> Pavel Bykov
> Sent: Dienstag, 7. April 2009 22:52
> To: `yc `lepi
> Cc: Mark Stephanus Chandra; ccielab_at_groupstudy.com
> Subject: Re: Output Drops on Interface
>
> eshedalonie, It is not a router but an L3 switch, so there is no fully
> functional WRED, and it all depends on a linecard installed.
> "show port capabilities" would reveal more information.
>
> ECN is not present on the platform in question.
>
> Furthermore, ECN is pointless. It was an interesting experiment, and it
> stayed that way. I had an ECN in the network for over a year, and NOT ONE
> SINGLE PACKET was ever ECN Capable, although billions were dropped by WRED
> across many routers.
>
>
>
> 2009/4/7 W W)W W W W W W <eshedalonie_at_gmail.com>
>
> > I Would use in such case QOS - WRED + ECN
> > To give buffer and avoid tail drop packets.
> > and also notify the tcp applications to slow down.
> >
> >
> >
>
> http://www.cisco.com/en/US/docs/ios/12_2t/12_2t8/feature/guide/ftwrdecn.html
> >
> >
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> >
> >
>
>
> --
> Pavel Bykov
> ----------------
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-- 
Pavel Bykov
----------------
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