Right... I added a command-line option to set the default interface MTU. Unless someone uses it, nothing changes...
See https://gerrit.fd.io/r/c/vpp/+/25473 Dave -----Original Message----- From: Christian Hopps <[email protected]> Sent: Wednesday, February 26, 2020 2:12 PM To: Dave Barach (dbarach) <[email protected]> Cc: Christian Hopps <[email protected]>; John Lo (loj) <[email protected]>; vpp-dev <[email protected]> Subject: Re: [vpp-dev] Change interface default MTU to 1500 FWIW, I actually like the 9k default as I suspect it means that the code path for jumbo frames gets tested a lot more than is normal. If 1500 is the default I suspect jumbo frame bugs will begin to creep in and go unnoticed. It was nice not having to fix any 9k bugs when we started using VPP. :) With that in mind, a local config default override seems better than a compiled default change. Thanks, Chris. > On Feb 26, 2020, at 10:07 AM, Dave Barach via Lists.Fd.Io > <[email protected]> wrote: > > OK, how about this: I’ll add a VLIB_CONFIG_FUNCTION, or [more likely] add a > system default MTU parameter to one of the existing config functions. > > I’m sick of cluttering configs with interface MTU commands... > > Thanks... Dave > > From: John Lo (loj) <[email protected]> > Sent: Wednesday, February 26, 2020 9:47 AM > To: Dave Barach (dbarach) <[email protected]>; vpp-dev <[email protected]> > Subject: RE: Change interface default MTU to 1500 > > Hi Dave, > > My memory was that in data center or cloud environment it is desirable to set > MTU to jumbo frame size to avoid fragmentation by default. Thus the question > would be if it is reasonable to set default MTU size to 9000 for VPP and what > kind of problem is it causing that would be fixed by changing it to 1500. > > Regards, > John > > From: [email protected] <[email protected]> On Behalf Of Dave Barach via > Lists.Fd.Io > Sent: Wednesday, February 26, 2020 8:40 AM > To: vpp-dev <[email protected]> > Cc: [email protected] > Subject: [vpp-dev] Change interface default MTU to 1500 > > Folks, > > I’m considering changing the default interface MTU to 1500, from the current > value of 9000: > > ethernet_register_interface (...) > { > <snip> > /* Standard default ethernet MTU. */ > vnet_sw_interface_set_mtu (vnm, hi->sw_if_index, 9000); > <snip> > } > > I’ve pinged some folks, and nobody remembers why we’re setting the default > MTU to 9000. > > Thanks... Dave >
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