svn commit: r280971 - in head: contrib/ipfilter/tools share/man/man4 sys/contrib/ipfilter/netinet sys/netinet sys/netipsec sys/netpfil/pf
Robert Watson
rwatson at FreeBSD.org
Thu Apr 2 18:46:33 UTC 2015
On Thu, 2 Apr 2015, Hans Petter Selasky wrote:
>>> Does somebody here know what happens in these two cases:
>>>
>>> If we are transmitting using TSO, will the network adapter increment the
>>> IP ID field somehow? What happens if an outgoing IP packet resulting from
>>> a TSO packet get fragmented by a router?
>>
>> Quite possibly -- this is presumably specified by the NIC vendor, but it
>> would be good to do a bit of a survey and see what happens in practice.
>>
>>> In ip_fragment() when we create fragments we should increment the ip_id
>>> value for each fragment?
>
> I'm asking because the code in FreeBSD, since the beginning probably, just
> copies the IP header, and use the same IP ID for all the fragments ! This
> just hit my mind after some recent work in this area.
I honestly cannot believe you are proposing that.
Please go read about how IP fragmentation works. Having an identical IP ID in
ip_fragment() is the point of the function!
Robert
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