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September 1st, 2020 00:00

VC-init : use cases

I have a few questions

 

Currently we have Brocade only equipment with the exception of one NPIV 8gbit uplink coming from a Cisco UCS Blade Chassis

 

I configured VC-INIT on the Long distance port , connecting 2 sites over an 8gbit LINK on a Connectrix G620

However I want to generalize on VC-init throughout my fabrics.

It unlocks Virtual Channels, and hereby unlock QOS (zones), quarantaining, buffercredits per channel , ... , most of all better flow control

 

My questions are :

  • Suppose I leave it only on my intersite ISL , will VC support only be used for frames threspassing my site over the intersite ISL, but not originating from my initiator path , or over any ISL hops, nor towards my target destination  ?
  • Suppose I enable VC-INIT on all my E-PORTS (LD0 mode) , will all frames threspassing ISLs use VCs , but Fports still don't use it .
  • Suppose I enable it on all my switchports, would then also benefit my Host/Storage Nodes from the use of VCs ?
  • Is there a global setting to enable it switchwide ?
  • Are there any prerequisites other then that other FC vendors might not support it ?  Would it then be ok, that in respect to the intersection with the Brocade equipment , you would simply not enable it on the intersection port with such a solution ?

143 Posts

September 7th, 2020 00:00

Hi,

Virtual channels only E-port to E-port.

 

On your questions:

Suppose I leave it only on my intersite ISL , will VC support only be used for frames threspassing my site over the intersite ISL, but not originating from my initiator path , or over any ISL hops, nor towards my target destination  ?

Ed: Virtual channels is normally used over any E-port to E-port connection.

 

Suppose I enable VC-INIT on all my E-PORTS (LD0 mode) , will all frames threspassing ISLs use VCs , but Fports still don't use it .

Ed: Correct, f-port don’t use VC. (of course there are exceptions, see below.)

 

Suppose I enable it on all my switchports, would then also benefit my Host/Storage Nodes from the use of VCs ?

Ed: No. No f-ports.

 

Is there a global setting to enable it switchwide ?

Ed: No.

 

Are there any prerequisites other then that other FC vendors might not support it ?  Would it then be ok, that in respect to the intersection with the Brocade equipment , you would simply not enable it on the intersection port with such a solution ?

Ed: Brocade HBA’s (F-ports) can avail from virtual channels.

“16 Virtual Channels (VCs) per port. VC-RDY flow control can use these multiple channels for Quality of Service (QoS) and traffic prioritization in physical and virtualized network environments.”

 

Regards,

Ed

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