Re: [16NG] Re: traffic classification

[Alexandru Petrescu <alexandru.petrescu at motorola.com>]

JinHyeock Choi wrote:
> > > I think it _may_ be relevant here.  IPv6 has a Traffic Class
> > > field with defined values (see rfc2474 for 6bit DSCP, and rfc2597
> > > for AF Assured Forwarding values).  802.16 has Service Class
> > > service flow encodings (11.13.4 in 802.16-1004).  The mapping
> > > between the two should be specified here I believe.
> > >
> > > Basically one would need to define mappings between DSCPs and
> > > 802.16 Service Flow encodings.  Remark the mapping is not
> > > straightforward because DSCP uses 6bit while service field is on
> > > 4bit.  But not all values from 6bit need to be encoded either.
> > >
> > > I think 802.16 spec doesn't define these mappings.  Although they
> > > do define filter in the CS that interprets the IPv6 Traffic Class
> > > field.
> >
> > Anyone who understands in detail what 802.16 classification does,
> > feel free to jump in here... DJ?
> >
> > My assumption was that 802.16 defines a classification mechanism 
> > that can look at certain fields from IP packets and determine what 
> > service flow should be used, including all parameters used in the 
> > service flow. If this is not the case then you are right.
>
> Classification is the process by which a MAC SDU (IPv6 packet in our 
> case) is mapped onto a particular transport connection for 
> transmission between MAC peers (BS and MS in our case). The mapping 
> process associates an IPv6 packet with a transport connection and its
>  CID (Connection Identifier).
>
> Classifiers are matching criteria applied to each packet and consist 
> of some protocol-specific packet matching criteria such as
> destination IP address. If a packet matches the specified packet
> matching criteria (i.e. classifier(s)), it is then delivered to the
> SAP for delivery on the connection defined by the CID (Connection
> Identifier).
>
> You may find more detail in 5.2.2 of 802.16. I also put a figure in
>
> http://www.diffeo.com/16ng/fig.gif
>
> Thanks for your kind consideration.

JinHyeock, thanks for clarification.  I think it confirms my
expectations of how 802.16spec intends IPv6CS classifiers to work: by
looking at IPv6 headers.

Assume an IPv6 packet put by the SS's IPv6 stack on the 802.16MAC has
the Traffic Class equal to DSCP AF11 '001010' (rfc2597 - Class1 with Low
Drop Precedence).

_How_ does this convert into a service flow?

More specifically, what is the priority assigned to this service flow?
("traffic priority": sec 11.13.5 of 802.16-2004).  This encoding has
values from 0 to 7 with higher numbers indicating higher priority.  If
not the "traffic priority" value then what are the other service
flow-specific constants that this IPv6 DSCP (diffserv codepoint) 
converts into.

Thanks,

Alex


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