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Interface flowcontrol command

battanc
Level 1
Level 1

Analyzing the configuration of a catalyst-4500 for one of my clients (switch that has some problems), I have seen a large use of
the "flowcontrol" command in all modes (receive / send, on / off / desideres).
I never use it, but here it is used on nearly all Giga interfaces.
The question is: is it a good idea or are there any contraindications?
Thanks for any suggestion.
Claudio

2 Replies 2

Mark Malone
VIP Alumni
VIP Alumni

Its like a quick form of qos it tells the sender to slow down when the int is congested , whats the issue your running into on the switch ?

Flow control is a feature defined in the IEEE 802.3x specification, enabling a receiving device to signal congestion to a sending device, which allows for the sending device to temporarily halt transmission, alleviating congestion at the receiving device

  • Flow control— Some Fast Ethernet devices support flow control, where devices can send pause frames, which instruct the remote end to stop sending data for a specific period of time.

  • Flow control— Flow control is important for gigabit Ethernet connections, where it is reasonable for the receive buffers on a gigabit interface to become full due to the high speeds of data transfer, causing congestion on the interface

Joseph W. Doherty
Hall of Fame
Hall of Fame

Generally it's a bad to use because it blocks all traffic on the port unless your using Converged Enhanced Ethernet (or one of similar that support priority-based flow control).

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