Book Image

OpenFlow Cookbook

Book Image

OpenFlow Cookbook

Overview of this book

Table of Contents (17 chapters)
16
Index

Modifying a flow table with vacancy enabled

When the controller does not want the switch to make its own decision in removing the flow entries, then the controller can use the vacancy mechanism. In this mechanism, the switch informs the controller whenever the switch's resources (especially the number of flow table entries) are reaching some threshold value, called the vacancy threshold. Unlike the eviction mechanism, wherein the switch itself removes the flow entry from the flow table, when the vacancy is enabled, the switch informs the controller about this. This mechanism enables of the controller to delete or modify the existing flow entries in the system whenever the switch reaches its threshold point.

How to do it...

The controller should send the OFP_TABLE_MOD message to the switch to enable vacancy for a particular flow table. The switch processes this message and generates an OFPT_TABLE_STATUS event or message for the controller whenever the number of flow table entries in the...