Fibre Channel (SAN)

Reply
Visitor
Posts: 1
Registered: ‎08-19-2016

Port congestion index and high zero buffer credit figures

Hi Guys,

 

I have two IBM SAN96b's connected via 8GB E port ISL's the distance between them is less that 2K/3 miles.

 

I seeing high numbers in the port congestion index and high zero credit buffers figures.

 

portperfshow shows that im only sending about 10mb on average down the ISL, is it possible that im sending too many frames at the E port?

 

If so whats the best way to reduce this?

 

It doesnt seem to be a bandwidth issue more like the switch cant deal with the amounft of frames, is this thinking correct?

 

Thanks

External Moderator
Posts: 4,973
Registered: ‎02-23-2004

Re: Port congestion index and high zero buffer credit figures

@kevsta

 

can you post please a bit more info ?

 

is a point-to-point fibre ?

 

WDM ? if yes Vendor / Model ?

 

what type os SFP are you using ?

 

how is the port settings ?

 

is QoS enable or disable ? in most case this is the first cause by long distance.

 

 

TechHelp24
Brocade Moderator
Posts: 300
Registered: ‎08-31-2009

Re: Port congestion index and high zero buffer credit figures

Hello,

 

Are you seeing timeouts or discards on any port?

What application are you running (SVC, VTS, others)?

 

 

 

Any and all information provided by me is not reviewed, approved or endorsed by Brocade and is provided solely as a convenience for Brocade customers. All systems and all networks are different and unique. If you have a service affecting network problem, please open a TAC service request for service through Brocade, or through your OEM equipment provider. If this provided you with a solution to this issue, please mark it with the button at the bottom "Accept as solution"
Brocade Moderator
Posts: 105
Registered: ‎04-27-2009

Re: Port congestion index and high zero buffer credit figures

Hi kevsta,

 

the buffer credit zero counter is just an indicator influenced by many different factors, e.g. link distance, allocated buffers, average frame payload size, enabled features, possible backpressure, etc...

 

The question always is, what is considered high...

 

Can you please share the output of portstats64show of the ISLs with us?

 

TL

If this provided you with a solution to this issue, please mark it with the button at the bottom "Accept as solution".

Any and all information provided by me is not reviewed, approved or endorsed by Brocade and is provided solely as a convenience for Brocade customers. All systems and all networks are different and unique. If you have a service affecting network problem, please open a TAC service request for service through Brocade, or through your OEM equipment provider.

Join the Community

Get quick and easy access to valuable resource designed to help you manage your Brocade Network.