Subject: RE: [PCN] Fwd: I-D ACTION:draft-eardley-pcn-architecture-00.txt

From: Bob Briscoe <[email-masked]>
Date: Wed, 25 Jul 2007 01:03:06 +0100

Phil & other authors,

Just thought of one more possible gap:

Another bullet for the Intro:

   o QoS reservations are decoupled from routing system (within the PCN 
domain). I.e. admission control lays reserved traffic over routes given by 
the routing system without any pinning. Then if any of capacity, routing or 
topology changes, the routing system just moves all traffic, so reserved 
flows that can gracefully continue after a short disruption will do. We 
don't trigger any messages from the routing system to the QoS system to say 
routing has changed. So we don't have to deal with losing these messages 
during disastrous events, or with authenticating such messages.

[Of course, then, if there isn't enough capacity for the previously 
admitted traffic after
- both a capacity, routing or topology change
- and after the routing and protection system has had a chance to bring in 
new capacity or re-arrange the routing to fit,
then flow termination can bring the system back below its max operating point.]

Bob

____________________________________________________________________________
Bob Briscoe, <[email-masked]>      Networks Research Centre, BT Research
B54/77 Adastral Park,Martlesham Heath,Ipswich,IP5 3RE,UK.    +44 1473 645196  

_______________________________________________
PCN mailing list
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https://www1.ietf.org/mailman/listinfo/pcn

---

From: Michael Menth <[email-masked]>
Date: Wed, 25 Jul 2007 11:27:33 +0200

Hi Bob,

yes, that's a good point to add to the key benefits of the PCN 
architecture: It proposes a "resilience admission control" system: 
admitted flows can survive failures without additional signaling. This 
differentiates the PCN approach from many other AC methods. It is a 
consequence of the stateless core and, therefore, it fits well as second 
bullet.
http://tools.ietf.org/id/draft-eardley-pcn-architecture-00.txt

Regards,

    Michael

Bob Briscoe wrote:
> domain). I.e. admission control lays reserved traffic over routes 
> given by the routing system without any pinning. Then if any of 
> capacity, routing or topology changes, the routing system just moves 
> all traffic, so reserved flows that can gracefully continue after a 
> short disruption will do. We don't trigger any messages from the 
> routing system to the QoS system to say routing has changed. So we 
> don't have to deal with losing these messages during disastrous 
> events, or with authenticating such messages.
>
> - and after the routing and protection system has had a chance to 
> bring in new capacity or re-arrange the routing to fit,

-- 
Dr. Michael Menth, Assistant Professor
University of Wuerzburg, Institute of Computer Science
Am Hubland, D-97074 Wuerzburg, Germany, room B206
phone: (+49)-931/888-6644, fax: (+49)-931/888-6632
mailto:[email-masked]
http://www3.informatik.uni-wuerzburg.de/research/ngn

---

From: <[email-masked]>
Date: Fri, 27 Jul 2007 00:35:49 +0100

sounds good, will add bullet on these lines
thanks
phil

________________________________

From: Briscoe,RJ,Bob,XVR9 BRISCORJ R
Sent: Wed 25/07/2007 01:03
To: Eardley,PL,Philip,CXR9 R
Cc: [email-masked]
Subject: RE: [PCN] Fwd: I-D ACTION:draft-eardley-pcn-architecture-00.txt

Phil & other authors,

Bob

---

From: "Jozef Babiarz" <[email-masked]>
Date: Fri, 27 Jul 2007 01:36:07 -0400

Bob, we are getting a bit beyond what is in the charter, but the correct
thing to do would be to add additional capacity (additional paths) once
traffic hits level where new calls would be blocked. With this approach
additional revenue generating traffic could be admitted on to new paths
that are not congested. Need to leave this for time being until after we
complete working in current charter. But it's important that we get the
basic marking behaviors right, otherwise these more advanced features
will not be possible.
 
Regards, Joe
email:[email-masked]
Telephone:613-763-6098

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] 
Sent: July 26, 2007 7:36 PM
To: [email-masked]
Cc: [email-masked]
Subject: RE: [PCN] Fwd: I-D ACTION:draft-eardley-pcn-architecture-00.txt

Phil & other authors,

   o QoS reservations are decoupled from routing system (within the PCN
domain). I.e. admission control lays reserved traffic over routes given
by
the routing system without any pinning. Then if any of capacity, routing
or
topology changes, the routing system just moves all traffic, so reserved
flows that can gracefully continue after a short disruption will do. We
don't trigger any messages from the routing system to the QoS system to
say
routing has changed. So we don't have to deal with losing these messages
during disastrous events, or with authenticating such messages.

[Of course, then, if there isn't enough capacity for the previously
admitted traffic after
- both a capacity, routing or topology change
- and after the routing and protection system has had a chance to bring
in
new capacity or re-arrange the routing to fit,
then flow termination can bring the system back below its max operating
point.]

Bob

________________________________________________________________________
____
Bob Briscoe, <[email-masked]>      Networks Research Centre, BT
Research
B54/77 Adastral Park,Martlesham Heath,Ipswich,IP5 3RE,UK.    +44 1473
645196

---

From: Michael Menth <[email-masked]>
Date: Fri, 27 Jul 2007 12:01:14 +0200

Hi Joe,

what Bob proposes is not an additional feature that needs to be taken 
care of, but rather an observed property of the current PCN 
architecture, that's at least my understanding. The core is stateless (= 
free of reservations), in case that something bad happens inside the 
network, routing changes and admitted traffic is carried over backup 
paths. If then precongestion occurs with respect to the supportable 
rate, flows are terminated. This is a very nice feature of PCN and 
should be mentioned in the introduction. Note that traffic is only 
terminated if the backup capacity does not suffice which can be 
precalculated. We did lots of such research before.

Regards,

    Michael

---

From: "Jozef Babiarz" <[email-masked]>
Date: Fri, 27 Jul 2007 10:56:00 -0400

Thanks Michael for the explanation.

Regards, Joe
email:[email-masked]
Telephone:613-763-6098

-----Original Message-----
From: Michael Menth [mailto:[email-masked]] 
Sent: July 27, 2007 6:01 AM
To: Babiarz, Jozef (CAR:0S03)
Cc: [email-masked]; [email-masked]; [email-masked]
Subject: Re: [PCN] Fwd: I-D ACTION:draft-eardley-pcn-architecture-00.txt

Hi Joe,

Regards,

    Michael

Jozef Babiarz wrote:
> Subject: RE: [PCN] Fwd: I-D
ACTION:draft-eardley-pcn-architecture-00.txt
> Subject: RE: [PCN] Fwd: I-D
ACTION:draft-eardley-pcn-architecture-00.txt
> domain). I.e. admission control lays reserved traffic over routes
given
> - and after the routing and protection system has had a chance to
bring

---

From: Bob Briscoe <[email-masked]>
Date: Fri, 27 Jul 2007 18:36:18 +0100

Joe,

We could say that the routing system could optionally be driven by the QoS 
system.

Of course, my suggestion below was a statement saying a strength of PCN is 
that we don't _have to_ have that dependency.

Bob