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Agenda

Agenda. 1. QUIZ 2. LANS, WANS & THE DATA LINK LAYER 3. HOMEWORK & HOMEWORK FOR NEXT CLASS 4. Perroyclinic BIDDERS CONFERENCE 5. ETHERNET AND BEYOND 6. ARCHITECTURE 7. PHYSICAL LIMITS 8. HUBS, BRIDGES, ROUTERS 9. ATM 10. ENCAPSULATION/VPN.

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Agenda

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  1. Agenda 1. QUIZ 2. LANS, WANS & THE DATA LINK LAYER 3. HOMEWORK & HOMEWORK FOR NEXT CLASS 4. Perroyclinic BIDDERS CONFERENCE 5. ETHERNET AND BEYOND 6. ARCHITECTURE 7. PHYSICAL LIMITS 8. HUBS, BRIDGES, ROUTERS 9. ATM 10. ENCAPSULATION/VPN

  2. Physical/Data Link/Network/ Layers?

  3. Homework-P 1 of 3 A company has a corporate network which consists of five Ethernet LANs connected to a mainframe through 56 KBps lines. Each LAN has about 20 workstations which generate one message per second. Each message is 1000 bytes (8 bits per byte). Most workstations interact with each other on their LANs with only 20% of the messages being sent to the mainframe. The messages sent to the mainframe access a corporate database which services 50 I/O per second. How much of a congestion problem exists on the LAN, the WAN and the mainframe database.

  4. Homework P 2 of 3 An Advise To The Lovelorn database operates on a T-1 line. The average input is 1000 bytes of questions. The average output has 1Million bytes of answers. Database processing time averages 3 seconds. What is the total response time if you assume 8 bits per byte.

  5. Homework P 3 of 3 Ping ns1.bangla.net. How many packets were lost? What was the response time? Now do a trace route and see how many hops it takes to get to get to ns1.bangla.net.

  6. Homework Visit Web site http://www.openview.hp.com and take an interactive tour. (Note: You need to sign up) Chapter 1, Problems 10 & 12 Chapter 2, Problems 1 & 5 (less the drawing in 2-5)

  7. Group Project • Hand in Team Names & Members Names (They are due on September 15th) • Any questions on handout?

  8. Bidders Conference

  9. Local Area Networks • MANs and LANs • 802 Series/Origins • 802.3 • 802.4 • 802.5 • 802.6/DQDB • Data Link Layer Protocols

  10. LANs & Layers Source Port 802.2 Logical Link Control Data Link Layer 802.1 Bridging CSMA Token Token MAN IVD Wire- Future less CD Bus Ring 802.3 802.4 802.5 802.6 802.9 802.11 Physical Layer 802.7 Broadband Tag 802.8 Fiber Optic Tag

  11. Data Link & Physical Layer Entities--802.3 • Data Link Layer • Data Encapsulation & decapsulation • Establishes frame • Provides source & destination addresses • Provides error detection • Media Access Management • Interfaces with physical layer (tx/rx frame) • Buffers frame • Provides collision avoidance • Provides collision handling

  12. Data Link & Physical Layer Entities--802.3 • Physical Layer • Data Encoding & Decoding • Provides the signals to synchronize the stations (preamble) • Encodes the binary data stream to self-clocking Manchester • code at transmit site & decodes at receive site • Channel Access • Introduces the physical signal onto the channel on the • transmit side and receives it on the receive side • Senses if a carrier is on the channel • Detects a collision on the channel

  13. IEEE 802.3 Frame Format CSMA/CD 7 1 2/6 2/6 2 0 - 1500 0 - 46 4 To From addr addr Pre- amble Data Pad Check sum Start of frame delimiter Length of data field

  14. IEEE 802.5 Frame Format Token Ring 1 1 1 2/6 2/6 No Limit 4 1 1 To From addr addr Check sum Data 1 1 1 Frame control End delimiter SD AC ED Access control Frame status Starting delimiter Token

  15. IEEE 802.4 Frame Format Token Bus 1 1 1 2/6 2/6 0 - 8182 4 1 To From addr addr Check sum Data Frame control End delimiter Access control Starting delimiter

  16. IEEE 802.X Frame Format Efficiency What is the nominal efficiency of 802.3 (data vs. OH)? 72/1500= What is the nominal efficiency of 802.5 (data vs. OH)? 21/8182+= What is the nominal efficiency of 802.4 (data vs. OH)? 20/8182=

  17. Distributed Queue Dual Bus (DQDB)--IEEE 802.6 Bus A Computer Bus B

  18. Data Link Layer—NM View Framing: Character count Starting & ending with character stuffing Starting & ending flags & bit stiffing Coding: Error correction (Hamming distance) Error detection (Polynomial checksum)

  19. Data Link Layer-NM View Data Link Protocols: Synchronous Data Link Control (SDLC) High Level Data Link Control HDLC) Serial Line Internet Protocol (SLIP) Point-to-Point Protocol (PPP) Link Control Protocol (LCP) Network Control protocol (NCP)

  20. Ethernet And Beyond Ethernet: a. Is the current evolution of ALOHA, i.e., CSMA/CD (1) Ethernet bus data rate is 10 Mbps. When traffic reaches 40% to 70% Utilization (of the maximum) collisions cause degraded performance. (2) Utilization must be monitored to keep performance at an acceptable level. b. Has an OSI subset architecture and physical limits:

  21. Layers In The OSI Stack Application Presentation Session Transport Network Data Link Physical Network Management uses some of these levels to manage others But how do they relate to each other?

  22. Ethernet And Beyond Ethernet: a. Is the current evolution of ALOHA, i.e., CSMA/CD b. Has an OSI subset architecture and physical limits: Architecture: Network LLC Data Link MAC Sublayer Physical Convergence Layer PMD Sublayer Fast Ethernet

  23. Ethernet And Beyond Gigabit Ethernet: a. Is theoretically cheaper than FDDI and ATM b. Is 100 times faster than Ethernet c. Has an OSI subset architecture and physical limits:

  24. Ethernet And Beyond Gigabit Ethernet: Has an OSI subset architecture and physical limits: Architecture: Network LLC Data Link MAC Sublayer Reconciliation Sublayer Convergence Sublayer Physical PMA Sublayer PMD Sublayer

  25. Data Link Layer Framing: Character count Starting & ending with character stuffing Starting & ending flags & bit stiffing Coding: Error correction (Hamming distance) Error detection (Polynomial checksum)

  26. Ethernet And Beyond Gigabit Ethernet: Has an OSI subset architecture and physical limits: Topology Limits: Type 9 µ 50 µ 50 µ 62.5 µ Bal Shld UTP SM SM MM MM Cable Cable 1000BASE-LX 10 km 3 km 550 m 440 m 1000BASE-SX 550 m 260 m 1000BASE-CX 25 m 1000BASE-T 100 m

  27. Ethernet And Beyond Hubs, Bridges, Routers & Switches (ATM): a. Hubs (1) Overcome length and numbers limitations limitations by connecting each DTE to a hub or stacked hubs in a wiring closet. (2) Are easily managed with the installation of patch panels {especially patch panels with decent connectors}. b. Bridges switch data between LANS (1) Provide switching and filtering (2) Operate at the Data Link layer (3) Can be transparent and use spanning tree algorithms (4) Can be source routing and used in token rings or to connect token rings with ethernet LANS

  28. Ethernet And Beyond Hubs, Bridges, Routers & Switches (ATM): (continued) c. Routers (1) Operate at the network level and contain tables of addresses. (2) Can optimize network performance in areas of bandwidth and latency. (3) Are fundamentally slower than bridges. b. Switches (1) Are circuit or packet (2) Operate at various levels (3) Are the fundamental characteristic of ATM implementations (4) Management issues occur at the Network Layer

  29. Layers In The OSI Stack Application Presentation Session Transport Network Data Link Physical

  30. The Network Layer/ATM • Objective # 1: Minimize mean packet delay • Objective # 2: Maximize total network throughput

  31. The Network Layer/ATM • Architectural Views: • Internet Community: Networking should be connectionless. • Telephone & ATM Communities: Networking should be connection oriented.

  32. The Network Layer/ATM Internet ATM Email FTP ……. TCP IP ATM Data Link Physical

  33. The Network Layer/ATM • Routing Algorithms • Non Adaptive or Static Routing • Shortest Path • Flooding • Flow based • Adaptive • Distance Vector • Count-to-Infinity • Link State

  34. The Network Layer/ATM • Congestion Control (open loop) Algorithms • Leaky Bucket Algorithm--buffers unregulated packet flow and converts it to a regulated flow. Excess packets are thrown away. • Token Bucket Algorithm--allows host computers to save up packets and burst them (up to the maximum size of the bucket). Excess packets are saved at host.

  35. The Network Layer/ATM • Congestion Control (closed loop) Algorithms • Choke Packets--router advises source router it is getting too heavy a utilization. Response is voluntary. • Fair Queuing--routers have multiple queues for each output line, one for each source. • Hop-by-Hop Choke Packets--have choke packet take effect at every hop it passes through--what’s wrong with this as a network layer strategy? • Load shedding--routers through the packets away--what’s wrong with this as a network layer strategy?

  36. The Network Layer/ATM OSI ATM ATM layer layer sublyr Functionality CS Providing the standard interface 3/4 AAL SAR Segmentation and reassembly Flow Control Cell header generation/extraction Virtual Ckt path management Cell multiplexing/demultiplexing ATM 2/3 Cell rate decoupling Cell generation Header, Checksum & Frame generation Packing/Unpacking cells fromenclosing envelope TC 2 Phys Bit timing and physical network access 1 PMD

  37. The Network Layer/ATM/IP/SONET IP OSI SONET ATM ATM layer layer layer layer sublyr Functionality CS Providing the standard interface 3/4 AAL SAR Segmentation and reassembly Flow Control Cell header generation/extraction Virtual Ckt path management Cell multiplexing/demultiplexing ATM 2 2/3 4 Cell rate decoupling Cell generation Header, Checksum & Frame generation Packing/Unpacking cells from enclosing envelope TC 3 2 Phys Bit timing and physical network access 1 1 PMD

  38. The Network Layer/ATM The ATM Layer: a. Is regarded in the ATM community as a Data Link Layer. b. Has Network Layer functionality. c. Is connection oriented, using “Virtual Channel/virtual circuits. d. Does not provide acknowledgments--good or bad? e. Has two designated interfaces: (1) User-Network Interface (UNI) is between host and network (or possibly customer and carrier). (2) Network-Network Interface (NNI) is between switches (ATM version of routers).

  39. The Network Layer/ATM The ATM Layer five byte header: 4 8 16 3 1 8 Payload Type General Flow Control Virtual Path Identifier Virtual Channel Identifier C L P Header Error Check Payload Type Virtual Path Identifier Virtual Channel Identifier C L P Header Error Check How many payload types are there?

  40. The Network Layer/ATM Characteristics of ATM service categories: RTNRT Service Characteristic CBR VBR VBR ABR UBR Bandwidth guarantee Yes Yes Yes Option No Suitable for real time traffic Yes Yes No No No Suitable for bursty traffic No No Yes Yes Yes Feedback about congestion No No No Yes No

  41. The Network Layer/ATM ATM quality of service parameters: Parameter Acronym Meaning Peak cell rate PCR Max rate at which cell will be sent Sustained cell rate SCR Long term average cell rate Minimum cell rate MCR Minimum acceptable cell rate Cell delay varia toler CDVT Maximum acceptable cell jitter Cell loss ratio CLR Fraction of cells lost/delivered too late Cell transfer delay CTD How long delivery takes (mean to max) Cell delay variation CDV Variance in cell delivery times Cell error rate CER Fraction of cells delivered without error Cell misinsertion rate CMR Fraction of cells delivered wrong place Severly-errored SECBR Fraction of blocks garbled cell block ratio

  42. WAN-Virtual Circuits VPN VPN

  43. WAN-Virtual Circuits A reason to care: 1. Number of countries with identified collection involvement 1997: 37 1998: 47 1999: 56 2000:63 2. Where they’re from: Asia: 37% Europe: 19% Eurasia: 21% Middle East: 18% 3. Technologies targeted: Information Systems Electronics Sensors & Lasers Marine Systems Aeronautics Biological & Chemical Energetic Materials Manufacturing & Fabrication Nuclear Technology Power Systems Space Systems Signature Control

  44. WAN-Virtual Circuits • Problems For Management • VPN implementation, services & overall • utility vary widely--the single complete • solution that can meet all your needs does • not exist • (Depending on your environment) some • implementations hold distinct advantages • over others

  45. WAN-Virtual Circuits • Virtual Private Networking Version 2.0 • 1. What is a VPN? • 2. What is a tunnel? • 3. What is the relationship between VPNs and multi- • system management? • 4. What is significance of Service Level Agreements • (SLAs)?

  46. WAN-Virtual Circuits • Virtual Private Networking Enhancers • 1. IPSec: • A protocol that authenticates, encapsulates • (tunnels) and encrypts traffic across IP networks. • It supports key management, the Internet Key Exchange • protocol & various encryptions (e.g., DES & Tripple DES) • 2. Multiprotocol Label Switching (MPLS): • Defines a process in which a label is attached to an IP • header to increase routing efficiency and enable routers • to forward packets according to specified QoS levels. • Uses a tunneling technique.

  47. MPLS vs. Circuit Switching • MPLS • Minimizes changes to hardware by • routing and switching functions • Will establish pre-hop behavior • for delay sensitive traffic • Permits bandwidth reservation and • flow control over wide range of paths • Will permit bandwidth & other • constraints to be considered in computes • Provides ranking to individual flows so • during failure important flows go first • Circuit Switching • Hardware designs do not need to • change • Minimizes delay variations • Enables accurate bandwidth • reservations • Can automatically compute routes • over known/specified bandwidths • Can provide hard guarantees of • service and routing

  48. VPN Example: Cisco Secure Client CAMPUS InternetVPN and/or IP-VPN X.509 Cert Auth Mobile Dial Remote Access User with Cisco Secure VPN Client Cisco 7100 Series VPN Router VPN Administrator Extranet User with Internet Access Mobile Home User with Cisco Secure VPN Client Cisco Secure Access Control Server-AAA Extranet User with Cisco Secure VPN Client

  49. VPN Example: Cisco Secure Client • Advertised Features • Full compliance with IPSec and related standards • DES, 3DES, MD-5 & SHA-1 algorithms • Internet Key Exchange using ISAKMP/Oakley • Interoperates with virtually all PC Windows communications • devices: LAN adapters, modems, PCMCIA cards, etc. • GUI for configuring security policy and managing certificates • Easy to install and transparent to use with easy configuration • for deployment to end users • Security policy can be exported and protected as read only by • the VPN administrator

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