Subject: [dispatch] SIP Overload Control Design: Loop Control

From: "Moran, Timothy L." <[email-masked]>
Date: Fri, 1 May 2009 18:40:59 -0400

Volker,

A comment on the control loop paragraph in section 2 of the design
considerations for OLC:

"A control loop spanning multiple hops can be used if the sending entity
has full knowledge about the SIP servers on the path of a SIP message."
 
I read this as the sending entity is required to have full knowledge of
the entire path.  I offer that that may not be the case.  It may be
possible to only require knowledge of one level downstream.  This sounds
pretty much like your example except that the example limits the case to
"one" downstream server.  Referring back to the requirements case of two
load balancing servers and the upstream server "PA", server PA can
declare overload upstream by knowing that servers P1 and P2 are
overloaded.  
 
Perhaps what I am trying to say is that an upstream server in a managed
network would declare overload (upstream) based on knowledge that all
next-hop servers are overloaded.  
 
Br,
Tim M.