RE: [Sipping] Sip Performance Metrics: Average Hops per INVITE (AHI)and Average Hops per Session (AHS)

["Uzelac, Adam" <[e-mail]>]

Daryl,

This email has been in my queue for numerous days.  Sorry for the delay.
I think that establishing SIP performance metrics is a very valuable
exercise, and I appreciate the effort. Now as for the topic at hand, and
specifically the "Hops per x"....Outside of the AHI Tuna reference that
splashed into my head ;) here are some thoughts.  

Your looking into quantifying hop detection is congruent with recent
focus on draft-ietf-sip-hop-limit-diagnostics-03. Detecting the
existence of a loop is basically knowing a 483 has been returned. Right?
Why not just determine the frequency of 483 Too Many Hops messages?
draft-ietf-sip-hop-limit-diagnostics would help in determining the
culprit.

With that said, the metrics you put forth blow might be valuable in
determining propensity to the equivalent of post dial delay.  Just a
thought.

Adam

-----Original Message-----
From: Daryl Malas [mailto:[e-mail]] 
Sent: Friday, June 16, 2006 12:37 PM
To: [e-mail]
Subject: [Sipping] Sip Performance Metrics: Average Hops per INVITE
(AHI)and Average Hops per Session (AHS)

I have had a request to add a metric, which could help avoid routing
loops in an operators network.  I have come up with two metrics, and I
wanted to get feedback from the mailing list before I update the draft.
Here is what I'm thinking:


> Average Hops per INVITE (AHI)
> 
>  
> 
> AHI is calculated as an average and is defined as the number of hops 
> per INVITE request.  This metric is used to indicate potential 
> inefficient routing and/or help an operator detect and/or prevent 
> routing loops.
> 
>  
> 
> Variables =
> 
>             a = # of INVITE requests
> 
>             b = SUM of a "Max Forwards" value
> 
>  
> 
>                       (a * 70) - (b)
> 
>             AHI = ----------------------
> 
>                              a
> 
>  
> 
> The value of 70 is used based on the recommended origination value for

> each request as described in section 8.1.1.6 of [2]. Any consistent 
> value used by an operator or provider may be used in place of the 
> recommended value.
> 
>  
> 
> Average Hops per Session (AHS)
> 
>  
> 
> AHS is calculated in a similar manner to AHI; however, the "Max 
> Forwards" value is taken from each request associated with the entire 
> session as described in the following section 2.5.  This metric is 
> also used in a similar manner as AHI.
> 
>  
> 
> Variables =
> 
>             a = # of SIP requests
> 
>             b = # of completed sessions
> 
>             c = SUM of a "Max Forwards" value
> 
>  
> 
>                     (a * 70) - (c)
> 
>             AHS =---------------------
> 
>                           b
> 
>  
> 
> The value of 70 is used based on the recommended origination value for

> each request as described in section 8.1.1.6 of [2].  Any consistent 
> value used by an operator or provider may be used in place of the 
> recommended value.
> 
Your feedback and thoughts are appreciated.

Thanks...

--Daryl


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_______________________________________________
Sipping mailing list  https://www1.ietf.org/mailman/listinfo/sipping
This list is for NEW development of the application of SIP
Use [e-mail] for questions on current sip
Use [e-mail] for new developments of core SIP