This is version 1.10. Setting the MTUs to take into account the additional GRE headers, was actually the only way to get packets of 1480<size<1500 to show up on the tunnel.
On Fri, Aug 23, 2013 at 4:55 PM, Jesse Gross <je...@nicira.com> wrote: > On Thu, Aug 22, 2013 at 5:24 PM, Theodore Elhourani > <telho...@email.arizona.edu> wrote: > > If the original packets are of length <= 1400, then they are successfully > > transmitted through the tunnel. Only when a packet is greater than ~1480 > it > > gets dropped. You are right the ip stack is fragmenting the large > packets, > > but because some of them are a notch below 1500 they are passed as is. > For > > these packets, adding gre/ip headers would increase their size to > > > 1500bytes. Subsequently they are dropped. The reason may be because the > > packets are already beyond the ip stack of the host, and no further > > manipulation of the packets is done after this point. > > What version is this? If it is before 1.9 then setting > header_cache=false in the tunnel options may help. > > > Reducing the size of packets, via MTU tweaking, seems to be a common > > practice when gre is used. Any ideas on this ? > > Regardless of the outcome of the above, setting the MTUs to take into > account the additional GRE headers will improve performance. >
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