Subject: [CCAMP] Comments on the draft draft-ali-ccamp-te-metric-recording-01.txt

From: [email-masked]
Date: Thu, 22 Mar 2012 17:38:22 +0800

Hi Authors

The draft is interesting since the performance metrics are more and more 
important when high-valued path needs to be provided.

If I catch the idea clearly, the recording te metrics (like delay,delay 
variation) are only related to the TE-links, why not consider the node's 
processing time?

When the network is constructed by the TDM switching and/or wavelength 
switching, I believe the delay of packet processing can be neglectful. 
However, considering that the cross-connection is blocking, different LSPs 
have different PHB behaviors, the port is rate-limiting, etc, the packet 
processing time may be a note value compared to the link delay in the 
packet switching world. 

Do I have a misundertanding or the draft just does not care about the node 
processing time? Hope your clarification. :)

Best regards

Fei

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From: "Zafar Ali (zali)" <[email-masked]>
Date: Sun, 25 Mar 2012 22:32:09 -0500

Dear Zhang: 

Thanks for raising this point; please see in-line.

Thanks

Regards ... Zafar 

From: [email-masked] [mailto:[email-masked]] 
Sent: Thursday, March 22, 2012 5:38 AM
To: Zafar Ali (zali); George Swallow (swallow); Clarence Filsfils
(cfilsfil); [email-masked]
Cc: CCAMP
Subject: Comments on the draft
draft-ali-ccamp-te-metric-recording-01.txt

Hi Authors 

When the network is constructed by the TDM switching and/or wavelength
switching, I believe the delay of packet processing can be neglectful.
However, considering that the cross-connection is blocking, different
LSPs have different PHB behaviors, the port is rate-limiting, etc, the
packet processing time may be a note value compared to the link delay in
the packet switching world. 

Do I have a misundertanding or the draft just does not care about the
node processing time? Hope your clarification. :) 

No, the draft *does* care about the node processing time and is written
such that it is equally applicable to packet switching as well as
non-PSC networks. 

The issue you raised can be solved by two ways: 

1.       In IGP advertisement, TE link metrics like delay and delay
variation also includes the expected node processing delays/ delay
variations. 

2.       Considering node processing delay and delay variation during
(RSVP-TE) recording. 

IMO (1) would be a better option. We will talk to the authors of TE
metric advertisement draft on this more and update this ID, accordingly.

Thanks

Regards... Zafar 

Best regards 

Fei