Wide Links and Wide Ports

Seto, Pak-lung pak-lung.seto at intel.com
Mon Feb 24 17:03:53 PST 2003


* From the T10 Reflector (t10 at t10.org), posted by:
* "Seto, Pak-lung" <pak-lung.seto at intel.com>
*
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No, it explained very clear in the standard as you quoted in your email.
It can even use different PHYS.  The only requirement is that you can
not switch link until all the data frame has been acknowledged.  You can
even transmit and receive on two different links within the wideport.
 
Pak

-----Original Message-----
From: David Freeman [mailto:david.freeman at datatransit.com]
Sent: Monday, February 24, 2003 4:42 PM
To: t10 at t10.org
Subject: Wide Links and Wide Ports


I seem to be confused about how wide ports and wide links are handled.
Section 8.3.3.1.4 of the SAS spec. (rev. D) says...
 
"  A wide port shall only transmit DATA frames for a given I_T_L_Q nexus
on one phy at a time. The wide port may switch phys for DATA frames once
all of the previous DATA frames have been acknowledged by the link
layer. Read DATA frames and write DATA frames for the same I_T_L_Q nexus
may be transmitted simultaneously and may be on the same or different
phys."
 
Does this mean that inside a wide link all of the frames between and
including the "Command" frame and the "Response" frame will only occur
on one physical link?[Seto]  No 
 
This seems to defeat the purpose of having a wide link.
 
If there is any one out there that could help clear this confusion, I
would appreciate it.
 
Thank You 
 
David R. Freeman
Data Transit


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 No, it explained very clear in the standard as you quoted in your email.  It can even use different PHYS.  The only requirement is that you can not switch link until all the data frame has been acknowledged.  You can even transmit and receive on two different links within the wideport.
  
 Pak
 -----Original Message-----
From: David Freeman [mailto:david.freeman at datatransit.com]
Sent: Monday, February 24, 2003 4:42 PM
To: t10 at t10.org
Subject: Wide Links and Wide Ports


 I seem to be confused about how wide ports and wide links are handled. Section 8.3.3.1.4 of the SAS spec. (rev. D) says...
  
 "  A wide port shall only transmit DATA frames for a given I_T_L_Q nexus on one phy at a time. The wide port may switch phys for DATA frames once all of the previous DATA frames have been acknowledged by the link layer. Read DATA frames and write DATA frames for the same I_T_L_Q nexus may be transmitted simultaneously and may be on the same or different phys."
  
 Does this mean that inside a wide link all of the frames between and including the "Command" frame and the "Response" frame will only occur on one physical link?[Seto]  No 
  
 This seems to defeat the purpose of having a wide link.
  
 If there is any one out there that could help clear this confusion, I would appreciate it.
  
 Thank You 
 
 David R. Freeman
 Data Transit


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