#class_note
Practical Challenges
- Scalability The controller needs to be responsible for many switches
- Response time
- Reliability The network should survive the failures of the controller and switches
- Consistency If multiple controllers are used at the same time, they should behave consistently
- Security Network vulnerable to attacks on the controller
- Interoperability Should be able to co-work with legacy switches during transition period
Flow modify ->
controller packet out to add LLDP flows with output action ->
switch packet in to controller with LLDP response ->
spanning tree (keep alive!)