Re: RFC3697 [Re: [RRG] FLOWv6: IPv6 Flow Label to control DFZ forwarding]

[Brian E Carpenter <brian.e.carpenter@gmail.com>]

On 2008-08-01 23:20, Tony Li wrote:
>  
> 
> |Were you or any other RRG people involved in the creation of the
> |Flow Label?  
> 
> 
> As an onlooker, my perception was that the IPv6 header ended up having too
> many free bits in it and that compressing it would have cause unfortunate
> consequences for header alignment on 64 bit processors, so the thought was
> to leave it effectively as reserved space.  However, there were so many
> poorly justified uses for the space, that the IPv6 folks decided to allocate
> it to the then-popular notion of a flow label.  This kept others from
> requesting header bits and did not force them into a precise semantic
> definition for the field.
> 
> Effectively, today, it's reserved space.

One of the reasons that I helped write RFC3697 was to open the way
for efforts to change that, but not much has happened. There are lots
of things you could use it for today and stay conformant with
RFC2460 and RFC3697, but as I said, nobody does it.

However, I don't think 20 bits is enough for what Robin has in mind.
Effectively it only allows for 2^20 RLOCs and that is only 4 times
today's DFZ if I have the arithmetic right.

    Brian

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