On 17/02/2017 04:59, Stewart Bryant wrote:
On 14/02/2017 23:00, Templin, Fred L wrote:
Unless there is operational assurance of
some size X>1280, however, tunnels have to use fragmentation to
guarantee that - at a minimum - packets up to 1280 will get through.
In that case there really needs to be a note about MPLS.
You can fragment into an IP tunnel, but not an MPLS tunnel, because you
cannot fragment the payload as you can in IPv4 and you cannot fragment MPLS.
I'm confused. A tunnel end point that accepts IPv6 packets MUST accept packets
of 1280 bytes (or shorter) and MUST emit them. How it gets them through the
tunnel is irrelevant - if it's an ATM tunnel it has to chop them into 48 byte
fragments and re-assemble them at the other end - if it's an avian carrier
tunnel
it might have to use several pigeons per packet*. None of this matters to the
IPv6
nodes concerned; the physical MTU of the tunnel technology is irrelevant except
to the tunnel end points.
Brian
*In RFC 6214, we didn't consider this, but we should have.