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Re: IPv6 Flow Label

Brian E Carpenter wrote :


So the rule is really only that the flow label
must be delivered *exactly* as it was set by the source host (and the
default setting is zero).

Right.
However, between source and destination hosts *of IPv6 packets*.
On an A-TURN-B path, the *destination host* of a packet from A is TURN (not B). 


TURN has to obey that rule like any other
device that forwards packets.
TURN is in this respect like any other function that operates with different 5-tuples on its upstream and donwstream interfaces (above the IP layer). 


Following the discusion, this is IMHO the right logic:
TURN nodes may freely support or not support RFC 3697 flow labels, as sources on their outgoing interfaces,. Independently, they may freely ignore received flow labels, or process them to optimize their transport flow recognition, on thir incoming interfaces.
If RFC 3697 flow labels are implemented by the two end nodes and by an intermediate TURN node, then packet classification can take advantage of flow labels in all traversed routers, be it with changed flow label values across the TURN node. 


Rémi