Re: [CCAMP] Network Assigned Upstream Label - Draft Update

[John E Drake <[e-mail]>]

Giovanni,

The contention window is closed w/ the second option.  When the ingress receives the Resv, the wavelength has been allocated within the network.  With the first option, when the ingress receives the Path_err, the wavelength has *not* been allocated within the network and the ingress is effectively starting over w/ a new Path.

Furthermore, acceptable label set is generated hop by hop.  This means that its use within an optical network to determine a valid e2e wavelength would require a potentially unbounded number of crankbacks, both single and multi-hop, with no guarantee that such a wavelength could be found.


Yours Irrespectively,

John

From: Giovanni Martinelli (giomarti) [mailto:[e-mail]]
Sent: Friday, February 28, 2014 6:36 AM
To: John E Drake
Cc: Vishnu Pavan Beeram; [e-mail]
Subject: Re: [CCAMP] Network Assigned Upstream Label - Draft Update

Hi John,

yes clear,  I was just bringing back on the table discussion we got on the same problem. The second option in better (although contention window is reduced but not avoided) however we had no numbers to justify  that such optimization or ... at least not so strong  reasons to update a mechanism that was proven to work.

Cheers
G


On 28 Feb 2014, at 14:10, John E Drake <[e-mail]<mailto:[e-mail]>> wrote:


Giovanni,

Use of acceptable doubles the signaling overhead and opens up a contention window:

1)      Path
2)      Path_err w/ acceptable label
3)      Contention window
4)      Path w/ acceptable label
5)      Resv

Versus:

1)      Path w/ downstream assigned label request
2)      Resv w/ downstream assigned label

Also, it's generally considered a bad idea(tm) to include error messages in the normal operation of a protocol

Yours Irrespectively,

John

From: CCAMP [mailto:[e-mail]] On Behalf Of Giovanni Martinelli (giomarti)
Sent: Friday, February 28, 2014 4:54 AM
To: Vishnu Pavan Beeram
Cc: [e-mail]<mailto:[e-mail]>
Subject: Re: [CCAMP] Network Assigned Upstream Label - Draft Update

Hi Vishnu,

On 28 Feb 2014, at 13:26, Vishnu Pavan Beeram <[e-mail]<mailto:[e-mail]>> wrote:



(2) The use of Label-Set/Acceptable Label-Set was meant to be used for exceptions. Using it always for every setup request is a compromised solution.


At the time we discussed the wson signaling (http://tools.ietf.org/html/draft-ietf-ccamp-wson-signaling-06), the acceptable label set was considered good enough. Not sure it comes into play at every request since your label_set should have reasonably good labels.

Cheers
G