[Ns-developers] tag rework for next release

[Nicola Baldo]

Hi Mathieu,

Mathieu Lacage wrote:
> As a preparation for the ipv4 rework for next release, I finally spent
> some time to try to deal with some of the issues around the tag API:
> there are now two types of tags for each packet: 'packet' tags vs 'byte'
> tags. Their semantics are slightly different to try to solve two
> different use-cases:
> 
> 1) byte tags could be typically used for flow ids: they will be
> preserved across packet fragmentation and aggregation. byte tags can be
> added to a packet but they can't be removed piecemeal: you have to
> remove them all all at once or not at all.
> 
> 2) packet tags will typically be used for cross-layer interactions (they
> are presently used, for example, to convey the ipv4 ttl from the udp
> layer to the ipv4 layer). They could be used to convey qos tids from
> applications to a wifi layer. They can be removed one by one. The
> implementation is optimized to be really efficient when the tag removed
> is the last tag added (just like a stack).

Are the new "packet tags" suitable for handling PHY layer metadata? I am 
thinking of all the parameters which are currently passed as parameters 
to WifiPhy::SendPacket(). Can we put those parameters in a packet tag 
instead?


Regards,

Nicola