My understanding is that the OPES box is an application level intermediary,
that terminates connections from/to the origin server and the client. Further
there isn't anything that prevents multiple such boxes to be in the path
between the origin server and the client.
If my understanding is correct, I believe it will be important for OPES boxes
that are involved in a given session to discover each other and have an
understanding of what each is doing to the content. This will be especially
important in long running streaming media sessions where "end-to-end"
feedback is used by a source to dynamically readjust its rate/the content's
format etc. Consider the following scenario :
<- -C_OPES1.1--> <-------C_OPES1.2----->
(origin server)---(opes1)-------(opes2)-----------(client)
<-----------C_OPES2.1------> <--C_OPES2.2-->
opes1 : An OPES intermediary in the origin server's authoritative domain
opes2: An OPES intermediary in the client's authoritative domain
C_OPES1.1 : An "end-to-end" connection between the origin server and opes1
C_OPES1.2: An "end-to-end" connection between opes1 and the client
In this scenario,let's say opes1 measures the goodput of C_OPES1.2 and uses
this estimate to transcode the stream. Likewise, opes2 modifies the stream
based on the goodput estimate on C_OPES2.2. Each of the OPES boxes could
independently transcode the stream resulting in unstable operation in the
worst case and super-degradation of the content quality in the best case.
Am I getting something wrong here ?
- Jayanth
--
Jayanth P. Mysore
Networks and Infrastructure Research Laboratory,
Motorola Labs
Phone : (847) 576-8561