Accepted Solutions
Firstly controllers are required only if we are in need of Logical Switching,Distributed routing and for arp optimization purpose. Recommended numbers for controller deployment is 3 ,however for test/poc you can run with 1 controller as well but don't go above 3 controllers for whatever reason .All three controllers is assigned with set of roles (API,Persistence server,Logical Manager,Switch manager and director server).
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In order to avoid split brain scenario which is highly possible in any clustering technology(In our case controller clusters) there is a master for each of these roles and behind the scene a voting takes place to select the master.For leader election a majority of all cluster nodes are needed and in that case 3 controllers are perfect rather than 1,2 etc . If you go with 2 controllers,considering one of the failure scenario both the controllers wont be the able to communicate each other. You should certainly read "Control Cluster Topic"
Firstly controllers are required only if we are in need of Logical Switching,Distributed routing and for arp optimization purpose. Recommended numbers for controller deployment is 3 ,however for test/poc you can run with 1 controller as well but don't go above 3 controllers for whatever reason .All three controllers is assigned with set of roles (API,Persistence server,Logical Manager,Switch manager and director server).
.
In order to avoid split brain scenario which is highly possible in any clustering technology(In our case controller clusters) there is a master for each of these roles and behind the scene a voting takes place to select the master.For leader election a majority of all cluster nodes are needed and in that case 3 controllers are perfect rather than 1,2 etc . If you go with 2 controllers,considering one of the failure scenario both the controllers wont be the able to communicate each other. You should certainly read "Control Cluster Topic"