Overlays provide network architects the ability to customize a network without the overhead of deploying real links. Using tunnels, overlays interconnect dedicated resources through commodity infrastructure, resulting in a virtual network. Originally intended as a stop-gap to enable the incremental deployment of new protocols such as multicast, they are increasingly being used for more permanent purposes, including application-specific networks and virtual infrastructure.
This tutorial covers the basics of virtual and overlay networks, and how they can be used to simplify applications, network management, and testbed deployment. It discusses the unique opportunities afforded by this capability, the different overlay methods available, how they challenge the Internet architecture, and their current and inherent limitations. The tutorial presents basic concepts and taxonomies, focusing on principles, uses, and issues in overlay deployment, management, and support. It assumes a basic knowledge of network architecture, including hosts, routers, and tunnels, and uses examples from the Internet architecture to highlight interactions among tunneling, forwarding, and security.
The tutorial begins with the definition of virtual and overlay networks, discussing the characteristics of virtual links, virtual routers, and virtual hosts, and how they differ from their non-virtual counterparts. The particular impacts of virtualization on forwarding, routing, and naming systems are also discussed, and virtual networks are compared to VPNs and peer-to-peer networks.
Related work covers the origins of virtual networks in the M-Bone and 6-Bone, the differences between end-to-end overlays (X-Bone, DynaBone, GeoNet) and core-based overlays (RON, Detour, SOS, VNS, PPVPN). It also covers variants of multi-layer overlays (VAN, SuperNet, MorphNet), service overlays (Grid, PlanetLab, NetLab), and application overlays (A-Bone, YOID/Yallcast). Uses of overlays are presented, including testing new protocols and services, and network abstraction for sharing and protection.
The tutorial considers the ways in which virtual networks extend and apply concepts from virtual memory, as well as the impact of virtualization on the future Internet architecture. Challenges are presented, including host and router extensions, multihoming, protocol extensions for routing, transport, and naming, and support for recursion (overlays on overlays). Advanced concepts are covered, including deployment, management, and monitoring, ways to support recursion and revisitation (one node emulating many), and path and component placement optimization. Finally, future directions are examined, including ways to integrate virtual networks with VPNs and peer-to-peer nets, uses of virtual nets for infrastructure management, and the ultimate convergence of virtual networks and virtual memory concepts.
Part num/titles: 6 parts:
- Background
- Uses of Overlays
- Survey
- Challenges
- Advanced Concepts
- Future Directions
Total presentation time: 3:36 (216 minutes)
Total number of slides: 134
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