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Negative impact of enabling flow control?

Is there any negative impact of enabling flow control on a 3750? I noticed that it only supports inbound packets.

Thanks!

John

HTH, John *** Please rate all useful posts ***
5 REPLIES
Hall of Fame Super Bronze

Re: Negative impact of enabling flow control?

John,

No negative impact on the switch, however its usefulness depend upon the sending device as the switch can't send pause frames - it just receives it.

Please see the documentation for more info:

http://www.cisco.com/en/US/docs/switches/lan/catalyst3750/software/release/12.2_46_se/command/reference/cli1.html#wp2233510

HTH,

__

Edison.

Re: Negative impact of enabling flow control?

Thank you for the reply Edison. I think the main question that my management had is if we can enable across all ports and get better throughput. I don't think it's a good idea to enable across all ports, but what are your thoughts?

John

HTH, John *** Please rate all useful posts ***
Hall of Fame Super Bronze

Re: Negative impact of enabling flow control?

I don't think it's a good idea to enable across all ports

Why do you feel this way after reading what it does?

My thoughts are, if you are experiencing congestion and dropped packets - Flow Control is a great tool to inform the sending partner to slow down its transmission. To me, that is a great benefit.

__

Edison.

Re: Negative impact of enabling flow control?

I don't necessarily "feel" that way. We don't have congestion on the network that requires this to be enabled, and I've read other forums where people have enabled it and it caused problems.

I always get concerned when I enable something that is disabled by default.

John

HTH, John *** Please rate all useful posts ***
Hall of Fame Super Bronze

Re: Negative impact of enabling flow control?

I always get concerned when I enable something that is disabled by default.

It's disabled by default because the behavior is hardware specific.

For instance, in the 3750 - it only allows you to receive pause frames, not send - while in the 6500 switch, you can send and receive pause frames.

Flow Control is just a quick and dirty QoS Layer2 mechanism - how do you feel about QoS? :)

__

Edison.

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