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Question regarding Virtual Connect Flow Control

Trusted Contributor

Question regarding Virtual Connect Flow Control

Francisco had a question regarding Virtual Connect flow control capabilities:




Hello everybody,


I would like to know if any of you in this distribution list can help me with the following situation since I have been looking multiple guides and no help.


Customer is having issues with the pause frames (400,000) and he was recommended to do this:


What this advisory says is that customer should disable the flow control running the command:


Set advanced-networking flowcontrol=off


He was able to run the command in his VC Ethernet modules running fw version 3.15 since the iSCSI Coockbook says this:


Beginning with VC 2.30, a VC Administrator can change the behavior of Flow Control through the VCM CLI.  This CLI command is a private/hidden command.


In the other hand, when he tries to run this command in his VC Modules running firmware version 2.12 he gets the following error:


ERROR: Invalid property : FlowControl.  The reason is that this is not a valid part of the command syntax for set advanced-networking on the 2.12 VC firmware.  The only valid syntax for the firmware he's running is "set advanced-networking [PacketBufferOverAllocationRatio=<ratio>]


Of course the recommendation would be to upgrade to 3.15 / 3.17, however they cannot do it for now, they will do the upgrade in two weeks but the customer would like to know if setting the packet buffer over allocation ratio is equivalent to turning off flow control for set advanced-networking. If it is, what is the value in <ratio>?.


I tried to find everywhere this command but no luck L, so I guess my last option is to ask in via this way.


Thanks a lot for the assistance…




Mark had some good info:




No, Packet Buffer overflow has nothing to do with Flow Control. It has to do with allocating memory resources for buffering to a port.

In regards to Flow Control, Virtual Connect 2.12 didn’t have the option, it wasn’t’ implemented until Virtual Connect 2.30.




That gave Francisco the info he needed. Any other advice?