1. Copyright © 2005 Department of Computer Science 111 The Edge of Smartness Carey Williamson Department of Computer Science University of Calgary Email: carey@cpsc.ucalgary.ca

2. Copyright © 2005 Department of Computer Science 222 Main Message Now, more than ever, we need “smart edge” devices to enhance the performance, functionality, and efficiency of the Internet Application Transport Network Data Link Physical Application Transport Network Data Link Physical Core Network

3. Copyright © 2005 Department of Computer Science 333 The End-to-End Principle Central design tenet of the Internet (simple core) Represented in design of TCP/IP protocol stack Wikipedia: Whenever possible, communication protocol operations should be defined to occur at the end-points of a communications system Some good reading: –J. Saltzer, D. Reed, and D. Clark, “End-to-End Arguments in System Design”, ACM ToCS, 1984 –M. Blumenthal and D. Clark, “Rethinking the Design of the Internet: The end to end arguments vs. the brave new world”, ACM ToIT, 2001

4. Copyright © 2005 Department of Computer Science 444 The End-to-End Principle: Revisited Claim: The ongoing evolution of the Internet is blurring our notion of what an end system is This is true for both client side and server side –Client: mobile phones, proxies, middleboxes, WLAN –Server: P2P, cloud, data centers, CDNs, Hadoop When something breaks in the Internet protocol stack, we have to find a suitable retrofit to make it work properly We have done this repeatedly for decades, and will likely keep doing it again and again!

5. Copyright © 2005 Department of Computer Science 555 (Selected) Existing Examples Mobility: Mobile IP, MoM, Home/Foreign Agents Small devices: mobile portals, content transcoding Web traffic volume: proxy caching, CDNs Wireless: I-TCP, Proxy TCP, Snoop TCP, cross-layer IP address space: Network Address Translation (NAT) Multi-homing: smart devices, cognitive networks, SIP Big data: P2P file sharing, BT, download managers P2P file sharing: traffic classification, traffic shapers Security concerns: firewalls, intrusion/anomaly detection Intermittent connectivity: delay-tolerant networks (DTN) Deep space: inter-planetary IP

6. Copyright © 2005 Department of Computer Science 666 The Smart Edge Similar “tweaks” will be needed at server side Putting new functionality in a “smart edge” device seems like a logical choice, for reasons of performance, functionality, efficiency, security What is meant by “smart”? –Interconnected: one or more networks; define basic information units; awareness of location/context –Instrumented: suitably represent user activities; location, time, identity, and activity; perf metrics –Intelligent: provisioning, management, adaptation; appropriate decision-making in real-time

7. Copyright © 2005 Department of Computer Science 777 Example 1: Redundant Traffic Elimination

8. Copyright © 2005 Department of Computer Science 88 Basic Principles of RTE If you can “remember” what you have sent before, then you don’t have to send another copy Redundant Traffic Elimination (RTE) Done using a dictionary of chunks and their associated fingerprints Examples: –Joke telling by certain CS professors –Data deduplication in storage systems (90% savings) –“WAN Optimization” in networks (20% savings)

9. Copyright © 2005 Department of Computer Science 99 Redundant Traffic Elimination (RTE) 9 Purpose: Use bottleneck link more efficiently Basic idea: Use a cache of data chunks to avoid transmitting identical chunks more than once RTE process: –Divide IP packet into chunks –Select a subset of chunks –Store a cache of chunks at two ends of a network link or path –Transfer only chunks that are not cached Works within and across files Combines caching and chunking

10. Copyright © 2005 Department of Computer Science 10 RTE Process Pipeline 10 Improve traditional RTE Exploit traffic non- uniformities:  Packet size (bypass technique)  Chunk popularity (new cache management scheme)  Content type (content-aware RTE) Up to 50% more detected redundancy

11. Copyright © 2005 Department of Computer Science 11 TypeValueDescriptionExample Nulls57.1%Consecutive null bytes0x00000000 Text16.7%Plain text (English)Gnutella HTTP7.3%HTTP directivesContent-Type: Mixed6.2%Plain text and other chars14pt font Binary5.8%Random characters0x27c46128 HTML3.7%HTML code fragments Char+13.2%Repeated text charsAAAAAAAz Main Sources of Redundancy

12. Copyright © 2005 Department of Computer Science 12 RTE Summary 12 Improves traditional RTE savings by up to 50% Techniques can be used individually or together RTE very beneficial for wireless traffic –30% of users have 10-50% redundant traffic Proposed a novel content-aware RTE –Improve RTE savings by up to 38% Challenges of content-aware RTE –Needs refinement to be able to work on real traces, or exploit an appropriate traffic classification scheme –Needs improvement in execution time

13. Copyright © 2005 Department of Computer Science 13 Example 2: The TCP Incast Problem

14. Copyright © 2005 Department of Computer Science 14 Motivation 14 Emerging IT paradigms –Data centers, grid computing, HPC, multi-core –Cluster-based storage systems, SAN, NAS –Large-scale data management “in the cloud” –Data manipulation via “services-oriented computing” Cost and efficiency advantages from IT trends, economy of scale, specialization marketplace Performance advantages from parallelism –Partition/aggregation, Hadoop, multi-core, etc. –Think RAID at Internet scale! (1000x)

15. Copyright © 2005 Department of Computer Science 15 Problem Formulation High-speed, low-latency network (RTT ≤ 0.1 ms) Highly-multiplexed link (e.g., 1000 flows) Highly-synchronized flows on bottleneck link Limited switch buffer size (e.g., 100 packets) How to provide high goodput for data center applications? TCP retransmission timeouts TCP throughput degradation

16. Copyright © 2005 Department of Computer Science 16 Summary Data centers have specific network characteristics TCP-incast throughput collapse problem emerges Solutions: –Tweak TCP parameters for this environment –Redesign TCP for this environment –Rewrite applications for this environment (Facebook) –Smart edge coordination for uploads/downloads Summary: TCP Incast Problem

17. Copyright © 2005 Department of Computer Science 17 Concluding Remarks We need “smart edge” devices to enhance the performance, functionality, security, and efficiency of the Internet (now more than ever!) Application Transport Network Data Link Physical Application Transport Network Data Link Physical Core Network

18. Copyright © 2005 Department of Computer Science 18 Future Outlook and Opportunities Traffic classification QoS management Load balancing Security and privacy Cloud computing Virtualization everywhere Multipath TCP congestion control …