about the SAS XL state machine

Shogo Hamasaku hamasaku at d1.hw.necst.nec.co.jp
Fri Nov 14 02:29:19 PST 2003


* From the T10 Reflector (t10 at t10.org), posted by:
* "Shogo Hamasaku" <hamasaku at d1.hw.necst.nec.co.jp>
*
Hi all,

I have a question about the SAS XL state machine.

What do I do with the XL state machine of Phy#A after Step:3?
I could not find a description about this situation in SAS-1.1 rev.1. 
I think that the XL state of Phy#A depends on the priority of both requests.

Step:1  Phy#A is XL0:Idle

Step:2  Phy#A receives an OPEN Address Frame.
        Then, XL state machine of Phy#A changes from XL0 to XL1:Request_Path.

Step:3  Phy#A requests a Request Path to the ECM. 
        At the same time, Phy#A recives a Transmit Open request from Phy#B 
        via the ECR, because The ECM has determined to make a connection 
        between Phy#B and Phy#A.

So, I thought that a new state (XL11) could be add to the XL sate machine.

Transition XL1:Idle to XL11  
  - A Transmit Open request is received.

State description about XL11
  - This state shall compare a Request Path request arguments and 
    a Transmit Open request arguments according to the arbitration fairness 
    comparison. 
  - If a Request Path request is a higher priority, this state shall send a Backoff
     Retry or a Backoff Reverse Path response to a opposite Phy via the ECR.
  - If a Transmit Open request is a higher priority,  this state shall change to 
     XL5:Forward_Open.

Thanks,
Shogo Hamasaku
NEC System Technologies, Ltd.
  External:(+81)89-947-7901
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