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Following is a simple topology of broadcast using IP NW.

Features

Fault tolerance & Robustness

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One of the most important feature to have in controller, should have following capabilities:

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But even if we modify ONOS to create multiple paths for a pair of source and destination traffic will always be flowing which will be a waste of BW.

To over-come that, backup flows with arbitrary but unique matching criteria will be created which will not be matched to any traffic in network while a flow is a backup path not the active path but as soon as there is a failure in active path or user want to switch the path intentionally then packet header will be updated with arbitrary match criteria to match new active path, this packet processing will be done either in P4 or using OF experimenters in switch.

This procedure if of generating arbitrary match criteria and modifying packet header is similar to one also used in switching of RTP streams section below. This mechanism can evolve as an generic framework for packet processing.

ONOS also support clusteringsupports clustering so requirement for HA is met.

Support for LAG is not present in the ONOS at the moment, it is to be implemented. NOS like Pica8 support it we need to interface with it. 

Traffic Engineering

Controller should have a mechanism by which it is able to choose and setup best available intents for a according to specific traffic type. To achieve this controller should be able to determine:

• Quality of Link in terms of latency and bandwidth – Latency and Bandwidth of intents– With the known latency and bandwidth properties, controller should be able to determine which intents (more than one) to deploy for a specific traffic types(traffic types like live audio, video, logging are identified by vlan in most cases) with their priorities (in case of failure priority helps to choose for next intent) i.e. For a real time audio stream, latency of path is crucial a priority than its bandwidth (for sure there should be minimum bandwidth available to carry voice stream), for a normal video file play latency may not be crucial a priority and it can take longer path, for a an HD video file transfer high bandwidth can be important.Stream Switching latency – Time required to switch a stream from different sourcesa priority rather than latency.

Solution

To calculate latency :

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Real time bandwidth usage is available in ONOS which can be used in combination with port capacity can be used to know the actual available BW.Stream Switching Latency is to be less than 5ms. as described in stream switching section, still this is important to log and monitor the latency on each stream switch. A P4 program which reads the time difference of the last packet before stream switch and the first packet from new frame can notify controller about stream switch latency. Actually, the P4 code or experimenter used in Seamless switching can further be modified to have this latency notification function.

Switching of RTP streams

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