Wide Links and Wide Ports

David Freeman david.freeman at datatransit.com
Mon Feb 24 18:27:24 PST 2003


* From the T10 Reflector (t10 at t10.org), posted by:
* "David Freeman" <david.freeman at datatransit.com>
*
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I guess that confusing part would be "A wide port shall only transmit
DATA frames for a given I_T_L_Q nexus on one phy at a time"=20
This seems to be saying that within a given I_T_L_Q nexus only one phy
is in use at any given time.=20
=20
Does the wording of this section need to be clearer or am I
misinterpreting this sentence?
=20
David

----- Original Message -----=20
From: Seto,  <mailto:pak-lung.seto at intel.com> Pak-lung=20
To: 'David Freeman'   ;
t10 at t10.org <mailto:t10 at t10.org> =20
Sent: Monday, February 24, 2003 5:03 PM
Subject: RE: Wide Links and Wide Ports

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.
=20
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...
=20
"  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."
=20
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=20
=20
This seems to defeat the purpose of having a wide link.
=20
If there is any one out there that could help clear this confusion, I
would appreciate it.
=20
Thank You=20
=20
David R. Freeman
Data Transit


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 I guess that confusing part would be = "A wide port=20 shall only transmit DATA frames for a given I_T_L_Q nexus on one phy at = a time"=20 
This seems to be saying that within a = given I_T_L_Q=20 nexus only one phy is in use at any given time. 
 
 Does the wording of this section need = to be clearer=20 or am I misinterpreting this sentence?
  
 David
 ----- Original Message ----- 
black">From:=20 Seto,=20 Pak-lung 
To: 'David Freeman' ; = t10 at t10.org = 
Sent: Monday, February 24, = 2003 5:03=20 PM
 Subject: RE: Wide Links and = Wide=20 Ports
 

No,=20 it explained very clear in the standard as you quoted in your = email.  It=20 can even use different PHYS.  The only requirement is that you = can not=20 switch link until all the data frame has been acknowledged.  You = can even=20 transmit and receive on two different links within the=20 wideport.
  
 Pak
 -----Original Message-----
From: David Freeman=20 [mailto:david.freeman at datatransit.com]
Sent: Monday, = February 24,=20 2003 4:42 PM
To: t10 at t10.org
Subject: Wide = Links and=20 Wide Ports


 I seem to be confused about how = wide ports and=20 wide links are handled. Section 8.3.3.1.4 of the SAS spec. (rev. D) = says...
  
 "  A wide port=20 shall only transmit DATA frames for a given I_T_L_Q nexus on one = phy at a=20 time. The wide port may switch phys for DATA frames once all of the = previous=20 DATA frames have been acknowledged by the link layer. Read DATA = frames and=20 write DATA frames for the same I_T_L_Q nexus may be transmitted=20 simultaneously and may be on the same or different=20 phys."
  
 Does this mean that inside a = wide=20 link all of the frames between and including the "Command" = frame and=20 the "Response" frame will only occur on one physical = link?[Seto] =20 No 
  
 This seems to defeat the purpose = of having a=20 wide link.
  
 If there is any one out there that = could help=20 clear this confusion, I would appreciate it.
  
 Thank You 
 
 David R. Freeman
 Data=20 Transit


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