Re: [sip-overload] soc-overload-control-05

[Janet P Gunn <[e-mail]>]

Finally got a chance to come up for air and take a look at this.

Some comments, mostly nits.  The non-nit is the one about setting 
oc-validity.

Comments on draft-ietf-soc-overload-control-05

Sec 4.1 

Second paragraph refers to "Section X.X".  Probably supposed to be 5.1

Last paragraph - the statement "it SHOULD reduce, by the amount indicated, 
the
   number of requests going downstream to the SIP server from which it
   received the response ..." is perfectly true for the loss based 
algorithm, but not technically correct 

for the rate based algorithm.

Suggest either adding a "Note" as in other cases where you discuss 
differences for rate based, or reword 
it, possibly
"it SHOULD reduce, as indicated by the oc and oc-algo parameters, the
   number of requests going downstream to the SIP server from which it
   received the response ..."

4.3
last sentence
 should "and the oc-algo parameter." be added on to the sentence?

5.2 overload stability and the value for oc-validity. (NON-NIT)

In selecting an oc-validity value, you should also consider the time 
interval for requests form EACH 
upstream SIP client.

As an extreme example, consider a case where you have thousands of 
upstream SIP clients, and each one 
sends a message, typically, once a second.  Even if you are adjusting your 
oc value every 10 
milliseconds, you want an oc-validity of at least a second.  Otherwise, 
every time a client gets ready to 
transmit, it will have an expired oc value, and won't throttle.

Something like " A SIP server MAY use a shorter "oc-validity" time
   if each upstream SIP client attempts to send messages at a  high rate, 
and SHOULD use a longer "oc-
   validity" time if each SIP client  operates at a lower rate." 

5.5 first paragraph
"The SIP client
   MUST NOT forward more requests to a SIP server than allowed by the
   current "oc" parameter value from a particular downstream server."
should probably be 
"The SIP client
   MUST NOT forward more requests to a SIP server than allowed by the
   current "oc" parameter value from that particular downstream server."

5.8.  This isn't really about "Stabilizing overload control" but about 
"Stabilizing overload algorithm 
selection".  Suggest changing section title.


5.10.2 last paragraph says 

"A SIP server that is under overload and has started to throttle
   incoming traffic MUST reject this request with a "503 (Service
   Unavailable)" response without Retry-After header to reject a
   fraction of requests from upstream neighbors that do not support
   overload control."

"fraction" is probably the right word if the server is using a loss based 
algorithm, but probably not the 
right word if it is using a rate based algorithm.

Maybe "A SIP server that is under overload and has started to throttle
   incoming traffic MUST reject this request with a "503 (Service
   Unavailable)" response without Retry-After header to reject some
   requests from upstream neighbors that do not support
   overload control."

Thanks

Happy New Year

Janet