Re: [sip-overload] draft-ietf-soc-overload-control-07 section 6.3 algorithm

[Adam Roach <[e-mail]>]

Sigh. Eric and I have been discussing this just now, and we got our 
messages crossed. He fixed one of about four problems with his changes 
below. See my message of about 2 minutes ago for a proposal that fixes 
several other issues.

/a

On 3/7/12 1:10 PM, Eric McMurry wrote:
> I'm a bit confused on the default loss-based algorithm in section 6.3 of draft-ietf-soc-overload-control-07.  Based on the text, I believe that this algorithm is intended to apply to outbound messages from a client and to use previously stored information about the overload condition of the downstream server the message is targeted to.
>
> When I read through the algorithm part though, I'm not sure of the intent.  I've made some changes in the algorithm to try to communicate what I think it was saying.  Does this match the intent?
>        cat1 := 40.0          // Category 1 --- subject to reduction
>     cat2 := 100.0 - cat1  // Category 2 --- Not subject to
>                           // reduction.  40/60 mix.
>     in_oc := false        // Not operating under overload
>
>     while (true)  {
>       sip_msg := get_outgoing_sip_msg()
>       if (is_response(sip_msg))  {
>           process_msg(sip_msg)
>       }
>       else if (is_request(sip_msg))  {
>
>         // Determine iftarget  server wants to enter overload or is
>         // in overload
>          target_server := extract_target(sip_msg)
>         in_oc :=lookup_in_oc(target_server)
>
>         // Get validity value
>         oc_validity :=lookup_oc_validity(target_server)
>
>         // Get oc parameter value
>         oc_value :=lookup_oc_value(target_server)
>
>         pct_to_reduce := oc_value / cat1 * 100
>         // Example: if oc=10,
>         // server uses 10 / 40 * 100 = 25 or 25% of messages in
>         // Category 1 can be reduced.
>
>         if (in_oc == false)  {
>           process_msg(sip_msg)
>         }
>         else  {
>
>           // Either Category 1 or Category 2
>           assign_msg_to_category(sip_msg)
>
>           if (oc_validity is in effect)  {
>             process_msg(get_msg_from_cat2())
>             sip_msg := get_msg_from_cat1()
>
>             // Draw a random number between 1 and 100
>             r := random()
>
>             if (r<= pct_to_reduce)  {
>                 // Do not send to server, handle locally by
>                 // generating a final response
>             }
>             else  {
>               process_msg(sip_msg)
>             }
>           }
>         }
>       }
>     }
>
>
>
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