Methods and apparatus are provided for controlling congestion in a network
such as a fibre channel network. Techniques are provided for
characterizing traffic flow at a congested network node. The congested
network node can generate various instructions such as quench messages to
control traffic flow towards the congested network node. The quench
messages can optionally include information about the characteristics of
the congestion. The instructions are distributed to other nodes in the
network. The other network nodes can interpret the instructions and
control traffic flow towards the congested node.