QSPEC: <Excess Treatment>
"Hannes Tschofenig" <[email protected]>
| Newsgroups | gmane.ietf.nsis |
|---|---|
| Message-ID | <[email protected]> |
Hi all,
"
The default excess treatment in case that none is specified is that
there are no guarantees to excess traffic, i.e. a QNE can do whatever
it finds suitable.
"
I think this sentence should make it clearer that "default" in this case
does not refer to a specific value of the <Excess Treatment> but rather to
the absence of the parameter.
"
When excess treatment is set to 'shape', it is expected that the
QoS Desired object carries a TMOD parameter. Excess traffic
is to be shaped to this TMOD. When the shaping causes
unbounded queue growth at the shaper traffic can be dropped. If
excess treatment is set to 'shape' and no TMOD parameter is given,
the E flag is set for the parameter and the reservation fails.
"
When a QoS Desired Object contains 2 TMODs, one for the regular QoS
treatment and another one for the shaping of excess traffic then how do you
differentiate the two? The text does not say anything about this case.
When excess treatment is set to 'remark', the excess treatment
parameter MUST carry the remark value, and the remark values and
procedures MUST be specified in the QOSM specification document. For
example, packets may be remarked to drop or remarked to pertain to a
particular QoS class (DSCP value). In the latter case, remarking
relates to a DiffServ model where packets arrive marked as belonging
to a certain QoS class/DSCP, and when they are identified as excess,
they should then be remarked to a different QoS Class (DSCP value)
indicated in the 'Remark Value', as follows:
Remark Value (6 bits): indicates either drop (set to 0) or DSCP
value to remark packets to when identified as
excess
The value of 0 is unnecessary since this can already be accomplished by
value 0 for the Excess Trtmnt.
Is the encoding of RFC 2474 used?
Ciao
Hannes