1. Campus Area Networking Technologies for routing packets from one LAN to another

2. Layer 3 Communication R S R S S S

3. Network - Layer 3 The network layer establishes the route between the sending and receiving stations. The node to node function of the data link layer (layer 2) is extended across the entire internetwork, because a routable protocol contains a network address in addition to a host address.

4. Application Presentation Session Transport Network Data Link Physical ©”A Guide to Networking Essentials”, 1998, Course Technology. OSI Reference Model

5. Routing BODY Layer 3 Header Layer 2 Trailer Layer 2 Trailer

6. Routers read packets up to layer 3

7. Network Routing Protocols for internetworking.

8. Two major types zPacket switching (or datagram) yUsually layers 3 and 4 zCircuit switching yUsually layers 1 and/or 2

9. Packet switching or Datagram Protocols zBest effort zFrames take individual routes zPacket assembly devices needed zError Control zTraffic Management yBuffering yDiscard

10. Node Functions zMessage forwarding zError detection and correction zTraffic management

11. Router Functions Routers perform layer 1, 2, and 3 functions yPacket passing xError correction yMessage routing xIncluding circuit definition yProtocol translation yFirewall functions (see the tracert function on the TCP/IP stack)

12. Switches and Routers Switch zExecutes in firmware zNot flexible zFast execution zInexpensive Router zExecutes in software zFlexible zSlow execution zExpensive Any logic that can be executed in software can also be converted to firmware using ASIC technology (application specific integrated circuits).

13. Routers Input Buffer Processor Output Buffer From AFrom B To CTo D Table of Addresses Input Buffer Output Buffer

14. Packet Routing zDatagram yPackets proceed along their own route and must be reordered at the end. zCircuit yPackets all take the same route and arrive in order

15. Datagram Logic (IP) Packet n Packet 1Packet 2 3 2 1 3 1 2 3 2 1 PAD

16. IP zBest Effort zAddressing zVariable packet lengths (1500 bytes or less) zIPv4 vs IPv6 zFrame and Header

18. The Internet: IP Addressing – IP v4 z32 bits (4 bytes) yNetwork address + Host address in one zClasses (originally) yA:126 nets, 3 bytes of client addresses yB:2 bytes of client addresses (e.g. OU) yC:1 byte of client addresses (256) zNext step – IPv6 y128 bit address space yWhy?

19. IP Header (Layer 3)

20. How IP Routing Works

22. IP Routing

23. Circuit Protocols zAll packets take the same route zNo packet assembly device to reorder packets zNormally layer 2 connection zMay be permanent or switched zAllow guaranteed service quality levels zMay be used to carry datagram protocols

24. Circuit Logic Source Destination Setup Message & ACK’s Teardown

25. Frame Relay zFrames relayed without reconstruction zEnd to end error control using CRC error detection at layer 3 level zVariable packet size zVirtual circuit (usually permanent) zMultiple data rates zMultiple quality levels

26. Frame Relay Pricing Components zPort speed yMeasured as Maximum Bit Rate (56K, T1, etc.) yUp to DS3 speed (45 Mbps) zProcessing quality yAccess (lowest) yBurst yCommitted

27. Frame Relay Processing Quality

28. Asynchronous Transfer Mode – layer 2 networking zCell switched zEqual length cells – 53 bytes yLike machine gun bullets zFast: Speeds up to 9953 Mbps zSupports Quality of Service classes zUsed primarily as a backbone technology

29. ATM Cell Format

30. ATM Traffic Classes (QoS)

31. Class of Service CoS) and Quality of Service (QoS) In an enterprise network, class of service (CoS) differentiates high-priority traffic from lower-priority traffic. Tags may be added to the packets to identify such classes, but they do not guarantee delivery as do quality of service (QoS) functions, which are implemented in the network devices. TechEncyclopedia, 2003(class of service)

32. QoS

33. Layer 4 Responsibilities: Connection zEstablish and release connections zControl between endpoints to avoid overflow zMultiplexing zCrash recovery (protection buffering) zData transfer zPacket splitting zExpedited delivery

34. Transport - Layer 4 The transport layer is responsible for overall end to end validity and integrity of the transmission. The lower data link layer (layer 2) is only responsible for delivering packets from one node to another. Thus, if a packet gets lost in a router somewhere in the enterprise internet, the transport layer will detect that. It ensures that if a 12MB file is sent, the full 12MB is received.

35. TCP and UDP Transmission Control Protocol zConnection oriented Assures that packets arrive in order and that they are correct. User Datagram Protocol zConnectionless Sends packets out without confirming that they arrive

36. TCP Header (layer 4)

37. Ethernet/TCP/IP Header Structure

38. UDP Routing

39. Layer 5 Responsibilities zDialog management zSynchronization of checkpoints for error recovery zActivity management to assure complete action messages

40. Session - Layer 5 Coordinates communications. Determines one-way or two-way communications and manages the dialogue between both parties; for example, making sure that the previous request has been fulfilled before the next one is sent. It also marks transmitted data with checkpoints to allow for fast recovery in the event of a connection failure.

41. Example: Ethernet/TCP/IP Stack

42. Backbone Protocols

43. Out to the WAN “cloud” Station Router/ Gateway Firewall WAN CSU/DSU LANBackbone

44. CSU/DSU: Digital Service Unit/Channel Service Unit

45. CSU/DSU Wide area access zThe Channel Service Unit terminates the external line at the customer's premises. It also provides diagnostics and allows for remote testing. zThe Digital Service Unit does the actual transmission and receiving of the signal and provides buffering and flow control. The DSU and CSU are often in the same unit.

46. Dual Ring Topologies (FDDI & SONET)

47. Dual Ring Operation

48. Rerouted Ring

49. FDDI Fiber Distributed Data Interface Common Backbone Technology zTwo Fiber Cables zDual Ring Configuration z4500 byte frame limit z100 Mbps zPriority Access zMultiple Frame Transmission z200 km (single mode fiber)

50. SONET Synchronous Optical NETwork zBackbone technology used by phone company. zLayer “1” yExternally synchronized z810 byte frame zDual ring topology zTime division multiplexing yMultiple simultaneous data streams

51. SONET CIRCUITS ServiceSpeed (Mbps) VT-1.51.7 OC-1 STS-151.84 OC-3 STS-3155.52 (3 STS-1s) OC-12 STS-12622.08 (4 STS-3) OC-48 STS-482488.32 (16 STS-3) OC-192 STS-1929953.28 (64 STS-3) OC-768 STS-76839813.12 (256 STS-3) OC (Optical Carrier) refers to the optical signal, and STS (Synchronous Transport Signal) refers to the electrical signal

52. ATM Asynchronous Transfer mode z53 byte cell y5 byte header / 48 bytes of data zSingle path for all packets in a message yDedicated circuit zQuality of Service Priorities

53. Typical SONET and ATM use as backbone technologies

55. 3 2 1 3 1 2 Inter- networking