On 10/11/2013 12:36 PM, Templin, Fred L wrote:
FWIW, my idea of the I-D is that it says "look, if you don't put all
this info into the first fragment, it's extremely likely that your
packets will be dropped". That doesn't mean that a middle-box may want
to look further. But looking further might imply
reassemble-inspect-and-refragment... or even reassemble the TCP stream
(e.g. think about a SSL/TCP-based VPN...)
We definitely don't want that. That is why we would prefer for
the entire header chain (starting from the outermost IP header
up to and including the headers inserted by the original host)
to fit within the first fragment even if there are multiple
encapsulations on the path.
The problem is that if you have multiple encapsulations, you can always
hit the MTU limit and fail to comply with this requirement.
That's why this I-D says what it says.
P.S.: Reegarding enforcing a limit on the length of the header chain, I
must say I symphatize with that (for instance, check the last individual
version of this I-D, and you'll find exactly that). But the wg didn't
want that in -- and I did raise the issue a few times. So what we have
is what the 6man wg had consensus on.
Thanks!
Cheers,
--
Fernando Gont
SI6 Networks
e-mail: fgont(_at_)si6networks(_dot_)com
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