Cabo: Concurrent Architectures are Better than One

1. Cabo: Concurrent Architectures are Better than One Nick Feamster, Georgia TechLixin Gao, UMass AmherstJennifer Rexford, Princeton

2. Network Virtualization

3. Flexible Network Topology

4. VINI: Virtual Network Infrastructure • Experimentation with new architectures (“bake off”) • Experiments can share same physical infrastructure • Important characteristics for repeatable experiments • Simultaneous experiments • Long-running “deployment studies” • Resource isolation UML XORP (routing protocols) eth0 eth1 eth2 eth3 Control Data Packet Forward Engine UmlSwitch element Tunnel table Click Filters

5. Idea: Infrastructure is the Architecture • Pluralist:No single “winning” architecture • Simultaneously running architectures • Network Operations • Transitioning to new software, configurations, etc. • Different networks for different services (e.g., VoIP) • Security: sandboxing unwanted traffic • Topology-specific routing protocols • ISPs “rent” slices of resources to each other • Or, perhaps even rent resources from third parties

6. Today: ISPs Serve Two Roles Role 1: Infrastructure Providers Role 2: Service Providers • Infrastructure providers: Maintain routers, links, data centers, other physical infrastructure • Service providers: Offer services (e.g., layer 3 VPNs, performance SLAs, etc.) to end users No single party has control over an end-to-end path.

7. Coupling Causes Problems • Deployment stalemates:Secure routing, multicast, etc. • Focus on incremental deployability cripples us • Shrinking profits and commoditization: ISPs cannot enhance end-to-end service • No single ISP has purview over an entire path “How do you think they're going to get to customers? Through a broadband pipe.. we have spent this capital and we have to have a return … there's going to have to be some mechanism for these people who use these pipes to pay for the portion they're using.” –Edward Witacre • Peering Tiffs: End-to-end connectivity is in the balance “As of 5:30 am EDT, October 5th, [2005], Level(3) terminated peering with Cogent without cause…even though both Cogent and Level(3) remained in full compliance …We are extending a special offering to single homed Level 3 customers. Cogent will offer any Level 3 customer, who is single homed to the Level 3 network on the date of this notice, one year of full Internet transit free of charge at the same bandwidth currently being supplied by Level 3. …”

8. Proposal: Concurrent Architectures are Better than One (“Cabo”) • The business entities that play these two roles may be the same in some cases • Infrastructure providers: maintain physical infrastructure needed to build networks • Service providers:lease “slices” of physical infrastructure from one or more providers

9. Similar Trends in Other Industries • Commercial aviation • Infrastructure providers: Airports • Infrastructure: Gates, “hands and eyes”, etc. • Service providers: Airlines BOS ORD SFO ATL • Other examples: Automobile industry

10. Communications Networks, Too! Two commercial examples • Packet Fabric: share routers at exchange points • FON: resells users’ wireless Internet connectivity Broker • Infrastructure providers: Buy upstream connectivity, broker access through wireless • Nomads: Users who connect to access points • Service provider: FON as broker

11. Application #1: End-to-End Services • Secure routing protocols • Multi-provider VPNs • Paths with end-to-end performance guarantees Today Cabo Competing ISPs with different goals must coordinate Single service provider controls end-to-end path

12. NYC Tokyo ATL Application #2: Virtual Co-Location • Problem: ISP/Enterprise wants presence in some physical location, but doesn’t have equipment there. • Today: Backhaul, or L3 VPN from single ISP • Cabo: Lease a slice of another’s routers, links

13. Challenge #1: Embedding • Given: virtual network and physical network • Topology, constraints, etc. • Problem: find the appropriate mapping onto available physical resources (nodes and edges) • Many possible formulations • Specific nodes mapping to certain physical nodes • Generic requirements: “three diverse paths from SF to LA with 100 MBps throughput” • Traffic awareness, dynamic remapping, etc. • Approximate solutions

14. Challenge #2: Simultaneous Operation • Problem: Service providers must share infrastructure • Approach: Virtualize the infrastructure • Nodes • PlanetLab • Virtual Machines • Virtual Routers • Links (previous lessons in QoS?) • Capabilities are similar to those needed for VINI • Many of the same functions needed • Likely more federation in Cabo

15. Challenge #3: Substrate • Problem: Service providers must be able to request physical infrastructure (infrastructure providers must be able to instantiate it) • Discovering physical infrastructure • Decision elements (cf. 4D proposal) • Creating virtual networks • Requests to decision elements (initially out of band), which name virtual network components • Instantiating virtual networks • Challenges include embeddingand accounting

16. Requirements • Router virtualization • Scheduling of node CPU, link bandwidth, etc. • Programmable software in each slice • Service providers will customize • Support for substrate • “Out-of-band” communication • Accounting: what bandwidth has been reserved?

17. Economic Challenges • Service providers: great deal • Opportunity to add value by creating new services • Service differentiation • Infrastructure providers • Can being an infrastructure provider be profitable? • Who will become infrastructure providers vs. service providers?

18. Summary • ISPs are infrastructure + service providers is problematic • Deployment stalemate • Commoditization • Cabo: “Concurrent Architectures are Better than One” • Separate infrastructure from service providers • Applications • Multi-provider VPNs, end-to-end services and protocols, … • Challenges • Simultaneous operation • Bootstrapping More Information: http://www.cc.gatech.edu/~feamster/papers/cabo-tr.pdf