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Contributor
Posts: 32
Registered: ‎06-09-2012

Buffer Credits


Hello All,

I could see lot of "Time BB_Credit Zero" errors on an ISL between to DCXs . Though I see there are enough buffer credits available, errors are increasing in a rapid pace. Based on formula for calculating buffer credits, I understand 332 buffer credits are needed for this ISL, fortunately it has 338 BCs.

Could someone please help me on which parameters i need to check apart from this???????

Many thanks in advance,

Rakesh P.

Super Contributor
Posts: 445
Registered: ‎04-08-2009

Re: Buffer Credits

Greetings rakesh.ponnada.

"Time BB_Credit Zero" isn't necessarily an indication of a problem as it is part of the FC flow control.  You can use this in conjunction with Tx frames and C3 discards to help identify slow drain devices.  Now it is possible a device, whether it be target or host is doing flow control without holding BBC's.  Now given root cause requires a little analysis, I'd recommend opening a ticket with support just to be on the safe side. 

Regards,

Mike Eversole
Brocade Community Manager
Contributor
Posts: 32
Registered: ‎06-09-2012

Re: Buffer Credits

Hello Mike, Thanks for your reply, Its very much informative.

Thanks,

Rakesh P.

Super Contributor
Posts: 445
Registered: ‎04-08-2009

Re: Buffer Credits

You are very welcome rakesh.ponnada! 

Regards,

Mike Eversole
Brocade Community Manager

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