Lecture 14 SDN and NFV. Antonio Cianfrani DIET Department Networking Group netlab.uniroma1.it

Transcription

1 Lecture 14 SDN and NFV Antonio Cianfrani DIET Department Networking Group netlab.uniroma1.it

2 Traditional network vs SDN TRADITIONAL Closed equipment Software + hardware Cost Vendor-specific management. Long delays to introduce new features High OpEx More than half the cost of a network. Operator error causes most outages. Bugs in the software device Failures, vulnerabilities SDN Control plane software runs on general purpose hardware. Decoupled from specific networking hardware. Use commodity servers and SDN switches (less cost). Programmable data planes. Data plane managed from a central entity. An architecture to control not just a networking device but an entire network.

3 SDN open points The control plane bottleneck The switches Flow Table size The communication channel switches/controller

4 The control plane bottleneck The Controller is a bottleneck of the SDN infrastructure: Scalability Security Single controller is not enough to manage a large scale network Multi Controllers Open Questions: How many controllers are needed? How to assign switch management to each controller? How to realize the communication among controllers? (synchronization)

5 The switch flow table size The flow table of an SDN switch is more complex than an IP routing table Matching possible on many fields Acts on flows high number of flows in a large scale network In new OpenFlow releases there are multiple tables Realized in TCAM (Ternary Content-Addressable Memory): memory technology for high speed searching applications TCAM limitation: about 1K entries not enough to cover all possible flows in a medium-size network Open Questions: TCAM (or new) technology evolution? Optimal assignment (in terms of flow table size minimization) of flow table entries to network switches

6 The communication channel switches/controller The communication channel among the switches and the controller is a critical component of the SDN architecture: No specifications Most feasible solution: realized using the data-plane infrastructure Open Questions: How to solve congestion problems? (priority)

7 SDN in action OpenFlow Switches (Juniper, NEC, HP, Pronto, ) Open Source OpenFlow release: Open vswitch Open Source SDN Controller NOX Floodlight ONOS and many more. Next lecture topic B4: Experience with a Globally- Deployed Software Defined WAN Download and read it!!!!

8 SDN use cases WAN-Traffic engineering Service Chaining for NFV Seamless workload migration Data Center Traffic Engineering / Energy Saving Port-Mirroring

9 Network Function Virtualization (NFV) Definition: an initiative to virtualize the network services that are now being carried out by proprietary dedicated hardware Same motivation of SDN! A network service is referred to as a Virtual Network Function (VNF): Router, Evolved Packet Core (EPC), Firewall, Intrusion Detection System (IDS)

10 NFV NFV aims at reducing OpEx by implementing network functions as virtual machine running on general purpose hardware NFV exploits advantages of virtualization technique Flexible provisioning, Mobility (migration), automation, hardware independence, pay-per-use, fault-tolerance,

11 NFV requires standardization of the interfaces and the communication among VNFs The VNF Forwarding Graph: NFV An end-to-end (E2E) service can be seen as a concatenation of Virtual Network Functions (VNFs)

12 NFV and SDN NFV and SDN are independent and complementary. NFV already implemented and tested by ISP. SDN is a network solution to realize NFV Service Chaining Data packets of the flow must cross all the VNFs composing its dedicated network service

13 SDN and Big Data