1. Univ. of TehranAdv. topics in Computer Network1 Advanced topics in Computer Networks University of Tehran Dept. of EE and Computer Engineering By: Dr. Nasser Yazdani Lecture 1: Introduction

2. Univ. of TehranAdv. topics in Computer Network2 Outline Agenda Policy, Grading, reading materials, etc. Overview of course materials Computer Network trend

3. Univ. of TehranAdv. topics in Computer Network3 Agenda To establish a base for future computer networks research and development. To discuss latest developments in computer networking and telecommunications via class lectures and assigned readings. To find the current research issues in the field. Finally, prepare to perform some projects in computer networks which are essential in national development, designing and building switches, routers, etc.

4. Univ. of TehranAdv. topics in Computer Network4 Course Materials Course Web page visit regularly Research papers Printed papers or pdf/ps format on the Website Combination of classic and recent work. Class notes of Dr. Turner on switching. Textbooks For Class reading “ATM switching systems” by Thomas M. Chen and.. “MPLS technology and Applications” by Bruce Davie and.. Background reading, so many books including: “Computer Networks, A system approach. Peterson & Davie 2 nd edition

5. Univ. of TehranAdv. topics in Computer Network5 Grading Homework assignments, around %20 Presentations One paper presentation, around 1 hour. Final project presentation, around 20 minutes. One hands-on assignment. Severe late penalties! Project around %45 Exam, final around %40.

6. Univ. of TehranAdv. topics in Computer Network6 Policy The course is research oriented. Then, the main focus will be project and paper reading. We will focus more packet switch, but open to new areas like mobile and wireless networks, QoS, etc. There will be a lot of reading and work. Then, be prepared!.

7. Univ. of TehranAdv. topics in Computer Network7 Covered topics The focus point of the course will be packet switching covering the following topics: 1. ATM networks 2. Switching architecture. 3. Lan switching, bridges, IP over ATM. 4. IP lookup 5. Packet classification 6. Label Switching. Tag switching, IP switching. Multiprotocol Label switching (MPLS 7. Network processors (?)

8. Univ. of TehranAdv. topics in Computer Network8 Asynchronous Transfer Mode Networks (ATM) ATM networks introduced commercially in early nineties. » designed to match packet networks’ ability to serve many different applications » improve support for real-time applications by allowing bandwidth reservation and support for guaranteed Quality of Service (QOS) » improve support for multicast applications with built-in signaling mechanisms » improve performance through high performance, scalable hardware switching » improve scaling using general hierarchical addressing and two multiplexing levels

9. Univ. of TehranAdv. topics in Computer Network9 ATM (Cont) Overall characteristics » cell-based switching with virtual circuit and virtual path routing » short, fixed-length cell to facilitate hardware switching & reduce delay variability » hardware support for unicast and multicast forwarding » general signaling protocol for establishment of unicast and multicast sessions » comprehensive traffic management framework supporting bandwidth reservation and QOS; emphasis on high quality services.

10. Univ. of TehranAdv. topics in Computer Network10 ATM (Cont) Competition between IP & ATM has improved both. » efforts to add QoS and multicast signaling capabilities to IP » introduction of hardware switching techniques in IP routers » improved congestion control mechanisms for data in ATM » extending ATM multicast to support many- to-many

11. Univ. of TehranAdv. topics in Computer Network11 Switching Switching systems » use cell labels to forward cells to destination » accommodate differences in terminal devices » allow large networks to be built economically Cell switches must be “programmed” to forward cells.

12. Univ. of TehranAdv. topics in Computer Network12 Switching (Cont) Input and Output Transmission Interfaces (ITI, OTI) »convert between serial optical signals and parallel electrical signals »extract timing from received signals »encode (and decode) data for transmission Input Port Processors (IPP) » synchronize received signals » determine required output or outputs using routing table Output Port Processors (OPP) »queue outgoing cells Shared bus interconnects IPPs and OPPs. Control Processor (CP) » configures routing tables to implement end-to-end channels » accepts requests for channels from terminals » coordinates end-to-end channel setup together with CPs in neighboring switches

13. Univ. of TehranAdv. topics in Computer Network13 Layer 2 switching Interlan switches, bridge are powerful but not scalable to WAN. Problem with Layer 2 switching is that it takes network as a flat network. Virtual LANS is used to overcome location limitation for LAN. VLAN is a broadcast domain, emulates the idea of being in the same physical LAN. More Flexible, Secure, Efficient compare to LANS By appending a Tag to the packet which identifies the VLAN.

14. Univ. of TehranAdv. topics in Computer Network14 WAN Switching There are two major problems in scaling LAN switching to WAN. Broadcast storm on the net. The size of lookup table. Switch needs a way to identify output port without broadcasting at startup.  Use existing switching technology to send IP ( IP over ATM)  Identify each flow with an ID.

15. Univ. of TehranAdv. topics in Computer Network15 IP Lookup  Packets are forwarded to their destination based on their destination addresses.  Router must find the address of the next hop for each packet by finding the longest prefix matching with the packet destination address.

16. Univ. of TehranAdv. topics in Computer Network16 IP lookup (Cont)  Example: If the a packet destination address is 101100111, the next hop will be 3 since 1011001 is the longest matching prefix.

17. Univ. of TehranAdv. topics in Computer Network17 Packet Classification Security and Filtering. Block unauthorized access. It is important on the access point of a network. Differentiated Services. Policy based routing. Billing. Isolating traffic from different users Quality of Service. Special queuing and scheduling. Traffic shaping.

18. Univ. of TehranAdv. topics in Computer Network18 General View FilterAction Classifier State Routing Input driver Output driver Scheduler IP input Processing IP Packet IP output Processing Reservation, Signaling & Management

19. Univ. of TehranAdv. topics in Computer Network19 General framework Each filter or rule consist of two sections, packet header information and actions or rule Packet headersRule or Action Header 1 Header 2 ….Header K Header information uniquely identify packet of a flow. Rule can be for security, forwarding or QoS of service rule. Questions?  Which combination of header fields?  How to formulize and map QoS, InterServ, DiffServ, etc. parameters to these rule?  How MPLS can be coupled with this classification scheme?

20. Univ. of TehranAdv. topics in Computer Network20 TAG Switching The idea is to identify a flow with an ID. It combines label swapping with network layer routing. It is the base of MPLS, Multiprotocol Label Switching, protocol. It was originally proposed by CISCO. The Components: Forwarding Control. Maintaining correct tags.

21. Univ. of TehranAdv. topics in Computer Network21 TAG Switching (Cont) Forwarding: is based on Label swapping. Each packet carry a tag, id with itself. There is a Tag Forwarding Information Base(TFIB) table in the switch. Incoming TagOutgoing TagOutgoing interface Outgoing link level inform. If the switch finds a entry with the incoming tag, it replaces the tag in the packet with the outgoing tag and the link information, and forwards it to the outgoing interface.

22. Univ. of TehranAdv. topics in Computer Network22 MPLS (Multiprotocol label switching) To utilize ATM switching technique in IP routers. This improve the price/performance of forwarding process. To simplify forwarding and routing process. Use MPLS tags for forwarding instead of IP header. This improve scalability of network layer forwarding. To extend the functionality and flexibility in bringing new services such as traffic shape, QoS, etc in an easy and manageable manner. And more …..

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25. Univ. of TehranAdv. topics in Computer Network25 Quality of Service Related topics Signaling and admission control. Traffic shaping Scheduling Buffer management Constrained based routing Quality of Service protocols for IP Integrated services RSVP

26. Univ. of TehranAdv. topics in Computer Network26 Network processor We can identified two almost independent parts in the design. Switch PHY NP0 NP1 SRAM ALU Inter face Network Processor SRAM 64 bits 32 bits 16 bits We are using two chips to implement the whole functionalities. We call each chip network processor for the sake of simplicity.

27. Univ. of TehranAdv. topics in Computer Network27 Network processor (Cont) The first Network Processor (NP0) does: Parsing Writing ingress packets in the SRAM Filtering Classification Reading and Dispatching egress packets to the Physical line. Sending packet headers to ALU for routing and NP1 for scheduling.

28. Univ. of TehranAdv. topics in Computer Network28 Network processor (Cont) The Second Network Processor (NP1) does: Scheduling Queuing Reading ingress packets from the SRAM Dispatching ingress packets to the switch. Receiving egress packet from switching and writing them into the RAM. Signaling for port and physical address finding.

29. Univ. of TehranAdv. topics in Computer Network29 Outline Agenda Policy, Grading, reading materials, etc. Overview of course materials Computer Networking trends

30. Univ. of TehranAdv. topics in Computer Network30 Trends Technology trends. Driving forces. Fast Immediacy Impact on R&D Impact on Education Convergence Information Glut Networking Trends

31. Univ. of TehranAdv. topics in Computer Network31 Driving forces Exponential growth. Number of Hosts on the Internet: Aug. 1981 213 Oct. 1984 1,024 Dec. 1987 28,174 Oct. 1990 313,000 Oct. 1993 2,056,000 Apr. 1995 5,706,000 Jul. 1997 19,540,000 Jul. 1999 59,249,900 Jul. 2001 117,288,000