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Hi, Robert,
It doesn't matter on what IP header this occurs.
It does matter whether it happens at the IP source (origin host, tunnel ingress, etc.) or on the path of that header.
The former is allowed exactly because it is where source fragmentation can occur (in IPv6, and preferably the only kind of fragmentation used in IPv4).
Joe
On 2020-02-27 15:04, Robert Raszuk wrote:
Joe, all,
Just to clarify something Fernando purposely missed in his call for action:
All operations on the packets discussed in SPRING WG are happening NOT on the original (end to end) packet header. They are all defined to happen within new imposed outer encapsulated header (IPv6 in IPv6 to be precise).
So original packet just get's tunneled between various points of the network. Last time I checked that operation is allowed by RFC2473.
Its subtle detail, but fundamental one to this entire context/discussion.
Kind regards,
R.
FWIW - there are separable issues here:
- whether an IP header (or parts thereof) should be changed in transit
AFAICT, the answer has always been yes, but limited to the hopcount/ttl in the base header and hop-by-hop options in the options/extension headers.
- whether an IP header length can change in transit
I see no reason why it can't become smaller, but if it can become larger then PMTUD and PLPMTUD don't work.
So the question isn't just what is wanted, it's what is feasible.
Joe
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