Ran,
You probably need to go through the mail archive and meeting minutes from the period when RFC 3697 was being developed to find all the arguments. That was most of 2002 and 2003. But I think the simplest form of the argument is that it is intended to allow rapid classification of a packet as belonging to a specific e2e flow, regardless of where that classification happens - and the only way to do that is an e2e label. If you allow mutability of the label, you break that property. If you want a mutable local field for QoS, use diffserv. If you want a mutable local field for switching, use MPLS.
It is true (see my comments on draft-chakravorty-bcc-flowlabel-00.txt) that this property allows certain use cases and makes life diffcult for others. But the converse would also be true.
Brian
Ran Liebermann wrote:
Hi,
I've been reading a few drafts and RFCs in this matter and I couldn't find an explanation why the Flow Label field has to read the destination with the same value the source sent it.
Wouldn't it introduce a whole lot of new capabilities (without as many limitations) if the Flow Label field had only local significance?
I've read drafts that describe local significance uses for the Flow Label field, but still they state that the destination has to receive this field as it was sent by the source. This ofcourse, if we plan to change this field hop-by-hop, requires some sort of synchronization between the first-hop-router after the source and penultimate router before the packet reaches it's destination.
I'd appreaciate if someone can explain this matter a little bit.
Thanks, -- Ran.
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