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Transcript of C2C communication
Controller to controller communication in distributed OpenFlow Network
By -Soumya Ranjan Parida
Agenda Introduction Motivation Architecture C2C communication protocol Advantages / disadvantages Conclusion
Introduction SDN is a new and increasingly
popular network architecture Main aim is to decoupling control
plane and data plane OpenFlow is a preferred protocol
Data Plane Application layer for management
and services(Ref:http://www.tcs.com/SiteCollectionDocuments/White%20Papers/Inter-SDN- Controller-Communication-Border-Gateway-Protocol-0314-1.pdf)
Motivation Scalability issue
A single controller might not be enough to service all nodes in the network. It would become a bottleneck in terms of processing power, memory, or input/output bandwidth. Bandwidth single point failure
Architecture-1Vertical Approach : Proposed by Deepankar Gupta and
Rafat Jahan -Working @TCS IDEA : Master controller over the individual
network controllers master controller, interfaces with the underlying
controllers using RESTFul APIs.
Though this approach can work for data centers,problems may arise if this model is to be scaled up in
an enterprise spread across different locations and
geographies. (Vertical Approach to Inter-SDN Controller Communication) (Ref:http://www.tcs.com/SiteCollectionDocuments/White%20Papers/Inter-SDN-Controller-Communication-Border-Gateway-Protocol-0314-1.pdf)
Architecture-1 Continue...Horizontal Approach :SDN east-west interface:Each controller can request for information or connections from its peers, that is, SDN controllers from other domains in the network.
Architecture-1 Continue ... The SDN east-west interface should
be able to coordinate the path setup requirement across multiple SDN domains Controllers need to exchange
information such as: Reachability update Flow setup, tear-down, and
update requests Capability Update
Protocols: A session needs to be established between the two controllers by using either BGP2 or Session
Initiation Protocol (SIP) over Transmission Control Protocol (TCP) to exchange information. Recommended Approach :BGP
Architecture-2Disco Architecture : DISCO is a distributed multi-domain
SDN control plane which enables the delivery of end-to-end network services. DISCO controller is in charge of a network
domain and communicates with neighbor domains.
composed of two parts Intra-domain Inter-domain
Architecture-2 Continue...Intra-domain : Monitor the network and manage the flow prioritization which help controller to compute the
route of priority flows.
dynamically react to network issues (broken link, high latency, bandwidth cap exceeded, . . . ) by redirecting and/or stopping traffic according to the criticality of the flow.
Inter-Domain :A DISCO controller communicates with neighbor domain controllers to exchange aggregated network-wide information.
Protocols : SDN controllers provide OpenFlow driver to implement the OpenFlow protocol, a switch manager and host manager to keep track of the different network elements, and link discovery implementing LLDP (Link Layer Discovery Protocol).
implements a unique control channel between neighboring domains. Messenger provides an open communication bus on top of which any agents can be plugged
dynamically. It can subscribe to topics published by other agents and start publishing on any
topic. Advanced Message Queuing Protocol (AMQP) as a base for the implementation of Messenger.
AMQP Protocol open standard and a thin application layer protocol for message-oriented middleware.
offers built-in features for message orientation, queuing with priority, routing (including point-to-point and publish-and-subscribe), reliable delivery and security.
Advantage :Being lightweight, highly controllable and software-oriented ,can be used for cloud management.used in OpenStack for loosely coupled communication between the different components.
Disadvantage :it makes the implementation of Messenger more complex.
Architecture-2 Continue...Agents :support QoS routing and reservation functionalities4 Main agentsConnectivity agent : charge of sharing with all the other domains the presence of peering links with neighboring
domains. sends information only if a new domain is discovered or a peering link changes. Store information in extended database.
Reachability agent :takes care, like RSVP, of inter-domain flow setup, teardown and update request including application capability requirement such as QoS, bandwidth, latency, etc.
Architecture-3DevoFlow: Motivation : SDN / OpenFlow can enable per-flow management However What are the costs and
limitations? always collecting all flows stat.s? what about controllers scalability ?
Proposal : DevoFlow to enable scalable flow mgmt by balancing
Network control Statistics collection Overheads Switch functions and controller loads
DevoFlow uses 1053 times fewer flow table entries at an average switch, and uses 1042 times fewer control messages
Architecture-3 Continue.. The controller maintains control over only targeted significant flows and has visibility over only
these flows and packet samples. DevoFlow is designed for simple and cost-effective hardware implementation
Our design principles are: Keep flows in the data-plane as much as possible. Involving the control-plane in all flow setups
creates too many overheads in the controller, network, and switches. Maintain enough visibility over network flows for effective centralized flow management, but
otherwise provide only aggregated flow statistics. Simplify the design and implementation of fast switches while retaining network
Architecture-3 Continue..Rule Cloning : Under the standard OpenFlow mechanism for wildcard rules, all packets matching a given rule
are treated as one flow. action part of a wildcard rule with a boolean CLONE flag. If the flag is clear, the switch follows the standard wildcard behavior. Otherwise, the switch
locally clones the wildcard rule to create a new rule in which all of the wildcarded fields are replaced by values matching this microflow, and all other aspects of the original rule are inherited.
Subsequent packets for the microflow match the microflow-specific rule, and thus contribute to microflow-specific counters.
Architecture-3 Continue..Local actions: Certain flow-setup decisions might require decisions intermediate between the heavyweight
invoke the controller and the lightweight forward via this specific port choices offered by standard OpenFlow.
local routing actions that a switch can take without paying the costs of invoking the controller.
Advantages/DisadvantagesAdvantages : Bandwidth on Demand Content Delivery Networks :Source SDN controller will need to communicate with the other
SDN controllers within the network to negotiate a path to the best possible CDN server that can meet the customer's QoS needs.
Scalability. A single controller might not be enough to service all nodes in the network. It would become a bottleneck in terms of processing power, memory, or input/output bandwidth.
Fault tolerance. minimize overhead
Disadvantages: issues in security and trust mechanism
Reference Distributed Multi-domain SDN Controllers (http://arxiv.org/pdf/1308.6138.pdf) Inter-SDN Controller Communication: Using Border Gateway Protocol (http://www.tcs.com/SiteCollectionDocuments/White%20Papers/Inter-SDN-Controller-Communication-Border-Gateway-Protocol-0314-1.pdf) DevoFlow: Scaling Flow Management for High-Performance Networks (http://conferences.sigcomm.org/sigcomm/2011/papers/sigcomm/p254.pdf)
Slide 1AgendaIntroductionMotivationArchitecture-1Architecture-1 Continue...Architecture-1 Continue ...Protocols:Architecture-2Architecture-2 Continue...Protocols :AMQP ProtocolArchitecture-2 Continue...Architecture-3Architecture-3 Continue..Slide 16Architecture-3 Continue..Advantages/DisadvantagesReferenceSlide 20