T Computer Networks II Introduction

Transcription

1 T Computer Networks II Introduction Matti Siekkinen

2 Contents Motivation and substance Why do we teach what we teach? What are the focus areas and how they relate to the big picture? Practical information Course Outline Passing the course Lectures and schedule Practical assignments Reading material

3 What is the Internet Architecture? Internet has a layered architecture Four layers Application (L7) Transport (L4) Network (L3) Link layer / physical (L2-L1) Layering has a big impact Benefits, limitations, possibilities (cross-layer)

4 Hourglass model Why an IP layer? make a bigger network global addressing isolate end-to-end protocols from network details/changes Why a single Internet protocol? maximize interoperability minimize number of service interfaces Why a narrow Internet protocol? assumes least common network functionality to maximize number of usable networks WWW phone..." SMTP HTTP SIP..." TCP UDP " IP" Eth PPP WiFi 3GPP " copper fiber radio OFDM FHSS..." Deering, 2001

5 ARPANET

6 The Internet has changed A lot of the assumptions of the early Internet has changed Trusted end-points Stationary, public addresses End-to-End

7 Textbook Internet vs. Real Internet H. Schulzrinne, 2009

8 Textbook Internet vs. Real Internet H. Schulzrinne, 2009

9 More about current state and trends Internet is growing fast Much of the growth comes from P2P and video delivery ~1 billion Internet users and ~5 billion mobile phone subscriptions Mobile Internet is anticipated to grow rapidly

10 More about current state and trends Internet of Things is a hot topic IPv6 address to each thing Talking about a lot of nodes Lot of traffic, potentially Machine-tomachine (M2M) communications Workloads differ compared to current ones

11 More about current state and trends Very difficult to change the Internet architecture We are stuck with IP and BGP Compare to IPv4->IPv6: well below 1% of traffic in over ten years Takes a long time to deploy new protocols in the waist Think about IPv6 Overlay solutions and middleboxes are common Lots of research on Future Internet over the last ten years Clean-slate vs. incremental evolution Difficult to envision clean slate proposals reach commercial deployment

12 Some of the challenges NAT and middle boxes Break the transparency/end2end Complicates protocol/service development Scalability Routing infrastructure Efficient content distribution IPv4 address depletion We already run out of them, IPv6 to the rescue Quality of service (QoS) Availability and reliability Security and privacy No need to explain

13 Some of the Internet s Challenges (cont.) Mobile nodes and data Connectivity and addressing are challenges We are running out of air! Usable spectrum for wireless communication is scarce Cognitive radios try to help Challenged environments Sensor networks Lack of or damaged infrastructure Standard Internet protocol suite does not work Sustainability Energy consumption and CO2 emissions of ICT Operational costs Governance Network neutrality

14 What do we teach? TEACHING TOPICS Transport protocols Data center networks Wireless Local Area Nws Wireless Personal Area Nws Delay Tolerant Networks Wireless Sensor Networks Network diagnostics Internet addressing Energy efficiency CHALLENGES NAT and middle boxes Scalability QoS Security and Privacy Mobile nodes and data Challenged environments Sustainability Governance

15 Advanced Transport Protocols IP layer: unreliable packet delivery between end-points Transport layer: reliability, congestion control, flow control for applications Problems of basic TCP Fat pipes Wireless networks Data center nws TCP variants There are really many Alternatives to TCP SCTP, DCCP, Swift & µtp,... 15

16 Data center networks Large data centers are essential for many service providers Web search, , content distribution, Google runs probably over 1 million servers by now Specific networking challenges Very small latency and high throughput within data center How to optimize costs? Infrastructure costs money (buy and maintain) Efficient, robust, and flexible data center architectures needed Cost efficiency Dynamic resource allocation (power efficient)

17 WLAN Wireless Local Area Networks , a.k.a. Wi-Fi Fairly long history -> many versions a, b, g, e, n, r... Specific solutions for Addressing Channel access Mobility Power saving Usage Medium range coverage Home, office, hotspots... WWW phone..." SMTP HTTP SIP..." TCP UDP " IP" Eth PPP WiFi 3GPP " copper fiber radio OFDM FHSS..." 17

18 WPAN Wireless Personal Area Networks Bluetooth ( ) Classic vs. Bluetooth Low Energy (BLE) ZigBee ( ) Widely used in sensor networks Centered around an individual person s workspace Specific characteristics Low cost Low power Short range 18

19 Delay Tolerant Networks (DTN) TCP/IP protocol stack assumes that network is connected Problems occur if Network is partitioned into several subnetworks Very long delays are involved (e.g. satellite communication) So called challenged networks DTN encompasses a large set of solutions for these situations

20 Wireless Sensor Networks Sensors have strict battery constraints Special emphasis on solutions for Routing Data aggregation Etc. Many applications Structure monitoring Smart home Health care Many industrial applications

21 Network diagnostics Impossible to provide QoS guarantees in today s Internet IP is unreliable, usually FIFO queues with tail drop Plenty of IETF work but very little deployed DiffServ, IntServ, NSIS We know how it could be done... Diagnosing problems and perceived QoS is important activity E.g. Service value may heavily depend on QoS

22 Network diagnostics (cont.) How is my network/services/clients doing? Surprisingly difficult question to answer What is/went wrong? Discovering root causes is even more difficult Important for Any enterprise network Ability to run basic services ISPs Want happy clients Service providers (e.g. Google) Want to provide better experience than competing services

23 Internet addressing Mobility On-going conversations X no longer associated with address Future conversations Where is X? what is the address? One solution is HIP Separate locator and identifier Locator: how to find X Identifier: Who is X? IP serves as both -> obvious problem with mobility Also provides Multihoming, Security, NAT traversal 23

24 Energy efficiency ICT consumes already quite a lot of energy Important because of $$$ and environment More efficient solutions exist and are being researched Another perspective: battery life of smart phones and sensors Growing gap between typical power budget and battery capacity of smart phones Battery technology & electronics are evolving but not fast enough Mostly a QoS issue A lot can be done by optimizing software

25 What we don t teach IPv4->IPv6 transition Solutions for interoperability Secure and scalable routing Secure routing protocols How to design and build fast routers Some taught on Future Internet architecture initiatives Check this fall Privacy and security in general See other lab courses: T-110.x2xx Wireless broadband networks WiMAX, UMTS, LTE 25

26 Course Outline 5 credit course Course consists of the lectures, a final exam, and assignments Some reading material provided beforehand Suggest to read it before lecture Everything will be in English 26

27 Course Goals Understand advanced networking techniques Learn state of the art Get a glimpse to near-future technologies and long haul development Most topics also related to our research interests and activities

28 Lectures: Time and Place Mondays at 14:15 16:00 in T2 Lecturers: Matti Siekkinen Miika Komu: Internet addressing Mario Di Francesco: Wireless Sensor Networks, WPAN

29 Reading material ~1 article/documents (RFC) per lecture Will be posted in Noppa (Additional reading section) before each lecture Read preferably before lecture Helps orientate to lecture Initiate discussion during lectures Material supports the lecture topics, not outside of them

30 Passing the Course Participation to lectures Highly recommended Final exam (60% of grade) :00-12:00 in T1 Based on lectures Practical assignments (40% of grade)

31 Assignments Assignments are done in pairs Form pairs yourselves Can use course s newsgroup to search partners opinnot.tik.t (web front end available at Each pair should complete two assignments Free to select those that you prefer Need to select from different lecture topics, though Course assistant helps with assignments Vu Ba Tien Dung [dung.vu.ba.tien@aalto.fi] Contact him for technical assistance No regular office hours, meet/advice on demand 31

32 Assignments (cont.) Topics Directly related to lectures Not all lectures, difficult to device meaningful experiments for some topics... Descriptions will be posted in Noppa with detailed instructions 32

33 Assignments (cont.) Important dates Mon 17.9.: Assignment topics published Fri :00: Deadline for assignment topic selection (and group formation) Fri :00: 1 st assignment deadline Fri :00: 2 nd assignment deadline Assignment delivery For each assignment, return a short report and source code package (if applicable) Report should include work done and results Technical report, not publication style -> no intro, background, etc. necessary Deliver in Optima (optima.aalto.fi) Some topics also require a demo Detailed instructions are given with topic descriptions 33

34 Assignments (cont.) Advice Start working early on (not just before dl!) Share work And do it fairly, both get same grade Contact course staff (me and assistants) in case of problems 34

35 Contact Points For general questions, send to me Follow course in Noppa Results and updates will be posted via Noppa news Reception Come and talk to me after lectures Otherwise send to arrange a meeting Exam reception will be scheduled on demand after results

36 Questions?