Re: MTU

[Saad Abdullah <saad17621 () gmail com>]

Worth reading this on choosing MTU on transit link.

http://blog.apnic.net/2014/12/15/ip-mtu-and-tcp-mss-missmatch-an-evil-for-network-performance/

-Sad



> > On Fri, Jul 22, 2016 at 10:01 PM, Baldur Norddahl <
> > baldur.norddahl () gmail com> wrote:
> >
> > > Hi
> > >
> > > What is best practice regarding choosing MTU on transit links?
> > >
> > > Until now we have used the default of 1500 bytes. I now have a project
> > > were
> > > we peer directly with another small ISP. However we need a backup so we
> > > figured a GRE tunnel on a common IP transit carrier would work. We want
> > > to
> > > avoid the troubles you get by having an effective MTU smaller than 1500
> > > inside the tunnel, so the IP transit carrier agreed to configure a MTU of
> > > 9216.
> > >
> > > Obviously I only need to increase my MTU by the size of the GRE header.
> > > But
> > > I am thinking is there any reason not to go all in and ask every peer to
> > > go
> > > to whatever max MTU they can support? My own equipment will do MTU of
> > > 9600
> > > bytes.
> > >
> > > On the other hand, none of my customers will see any actual difference
> > > because they are end users with CPE equipment that expects a 1500 byte
> > > MTU.
> > > Trying to deliver jumbo frames to the end users is probably going to end
> > > badly.
> > >
> > > Regards,
> > >
> > > Baldur