It is good to read this kind of draft when you are confronted with Access
Services defintion.
Good luck for the BOF. her-after are some quick remarks, in the coming days I
will try to map the services class we are working on with what is in the draft.
Remark/questions on Draft-tequila-diff-serv-sls-00
General :
Title "Service Level Specification Semantics,
Parameters and negociation requirements"
I like the title but either diff-serv is missing in it
or you should narrow the goal or you should put
for further work other technical notions which
are quite often in actual SLAs as redundancy,
monitoring, delay for problem notification.....
Other services as dial-up have additional indicator as
"successfull access/availability" or percentage of
rejected/released call. It is probably easier to
narrow the actual document to "always on type" of
service (permanently physically connected).
Detailed points:
&3.1 Excluding the many-to-many communication is
pretty limiting, How do you decribe a) a VPN with
network-wide priority or reserved global capacity; b)
wholesaling transport service sold per global capacity
(which is may be considered as a bigger VPN).
&3.5 Why excluding optional quantile for throughput ?
&3.5 Qualitative : You should explain why you need to
define qualitative performance (which does not fit
well with guarentee isnt it ?).
The delay and loss sub-class is not so easy to understand.
Green,yellow,red is associated with the 3-color marker concept
Gold, silver, bronse is usually associated with a full class
i.e. the combination of priority,loss, delay........
Do you think that low-delay/high-loss the same as a Service associated
whith a low delay at the detriment of loss ( dont
deliver data if delay exceeds an order of Nmsec) and
is low-loss/high-delay the same as a service with a
low loss at the detriment of delay.
I agree it is probably an endless discussion but SLS should allow
many different service implementations otherwise it will be rejected by
operators.
I think trafic priority or some relation to throughput
is also needed as a qualitative indication.
Finally I imagine all that qualitative discussion
is targetted to signalling-negociation, the problem here is not
technical but marketing, I dont imagine any operator
writing that he is selling a high-delay/high-loss
service.
Why not starting simple by signalling just the
name of the service which is required (for inter-domain as-well)
and optionally a range of indicative values
(e.g. target or average value).
Pierrick
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