Hi,
On Aug 3, 2010, at 02:53 MDT, Rémi Després wrote:
What about this combination (not documented yet, it seems)
- Hosts that send non 0 FLs, MUST do it with a value that:
. is common to all packets of their flow
. generally is different from one flow to another
- non 0 FLs MUST be preserved e2e.
- 0 FLs may be changed anywhere, but with the same constraints as in hosts.
Earlier I suggested that a modified "0 FL" should be reset back to zero
at the egress of the network that modified it. Someone said this is
impossible, which I don't believe at all. However, all I really care
about is that "0 FL" should be mutable and others shouldn't. Whether it
is or should be reset on egress doesn't matter to me.
In addition,
- A flow is specified by its 5-tuple, if it exists, or its 3-tuple otherwise.
- The FL value assigned to a flow MAY be EITHER:
. a hash of the flow identification (simple because stateless), OR
. a pseudo random number (more complex because stateful, but providing an
utmost privacy protection
The choice between hash or randomness is made where the FL is set. Other nodes
don't need to know what has been chosen.
On 08/03/10 17:20, Shane Amante wrote:
Because of your last two bullets I have to ask the following. How would a
receiving host deterministically distinguish (1) flow-labels that were created
by network devices (just a 5-tuple was put into a flow-label) vs. (2)
flow-labels that were created by a source-host w/ a pseudo-random number +
5-tuple[1]? (Please read on before answering :-)
Why does a receiving host care about the flow label at all? It exists to
make sure that all intermediate nodes give correct treatment to the
flow, but once it reaches its destination it's "safe", right?
What have I missed?
--
Aleksi Suhonen
Department of Communications Engineering
Tampere University of Technology
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