Software Defined Networking - Network Virtualization

a. History of SDN
This lesson: Network Virtualization
 - What is network virtualization?
 - What is its history? (w/examples)
— - 1990s (and before): Switchlets
— - Mid-2000s: VINI, Cabo
— - Looking forward
ž - Network virtualization and SDN
Evolution of Supporting Technologies
 - Central network control: Dates back (at least) to AT&T’s network control point (1980s)
ž - Programmability in networks: Active networks (1990s)
ž - Network virtualization: Switchlets (1990s), VINI (2000s)
What is Network Virtualization?
 - Representation of one or more logical network topologies on the same infrastructure.
ž - Many different instantiations
— - Virtual LANs (VLANs)
— - Various technologies and network testbeds
— - Today: VMWare, Nicira, etc.
Benefits of Network Virtualization
 - Sharing: Multiple logical routers on a single platform
ž - Sharing: Resource isolation in CPU, memory, bandwidth, forwarding tables, …
 - Customizability: Customizable routing and forwarding software
 - Customizability: General-­‐purpose CPUs for the control plane
 - Customizability: Network processors and FPGAs for data plane

b. Three Examples of Virtual Networks
Tempest: Switchlets (1998)
— - Separation of control framework from switches
— - Virtualization of the switch
ž - VINI: A Virtual Network Infrastructure (2006)
— - Virtualization of the network infrastructure
ž - Cabo: Separates infrastructure, services (2007)
The Tempest Architecture: Switchlets
 - Multiple control architectures over ATM
ž - Separation of switch controller and fabric via open signaling
ž - Partitioning of switch resources across controllers

c. Switch Divider
 - Partitions port space, bandwidth, buffers
ž - Different controllers control each switchlet

d. VINI: Virtual Network Infrastructure
 - Runs real routing software
ž - Exposes realistic network conditions
ž - Gives control over network events
ž - Carries traffic on behalf of real users
ž - Shared among many experiments

e. XORP: Control Plane
 - BGP, OSPF, RIP, PIMSM, IGMP/MLD
ž - Goal: run real routing protocols on virtual network topologies
Click: Data Plane
 - Performance
— - Avoid UML overhead
— - Move to kernel, FPGA
ž - Interfaces ð tunnels
— - Click UDP tunnels correspond to UML network interfaces
ž - Filters
— - “Fail a link” by blocking packets at tunnel

f. Concurrent Architectures are Better than One
 - Infrastructure providers: Maintain routers, links, data centers, and other physical infrastructure
ž - Service providers: Offer end-to-end services (e.g., layer 3 VPNs, SLAs, etc.) to users
 - Today: ISPs try to play both roles, and cannot offer end-to-end services

g. Examples in Communications Networks
ž - Two commercial examples in IP networks
— - Packet Fabric: share routers at exchange points
— - FON: resells users’wireless Internet connectivity
 - FON economic refactoring
 - Infrastructure providers: Buy upstream connectivity
 - Service provider: FON as the broker

h. Evolution of Supporting Technologies
 - Central network control: Dates back (at least) to AT&T’s network control point (1980s)
ž - Programmability in networks: Active networks (1990s)
ž - Network virtualization: Switchlets (1990s), VINI (2000s)
Goal: Control and Realism
 - Control: Reproduce results
— - Control: Methodically change or relax constraints
ž - Realism: Long-running services
 - Realism: Connectivity to real Internet
— - Realism: Forward high traffic volumes (Gb/s)
— - Realism: Handle unexpected events

i. Similar Trends in Other Industries
Example: Commercial aviation
 - Infrastructure providers: Airports
— - Infrastructure: Gates, “hands and eyes” support
— - Service providers: Airlines
Enabling End-to-End Services
 - Secure routing protocols
 - Multi-provider Virtual Private Networks
 - Paths with end-to-end performance guarantees