1. X.25 Overview

2. IP AppleTalk Novell IPX Banyan VINES XNS DECnet ISO-CLNS Apollo Compressed TCP Bridging SS X.25 Cloud X.25 Virtual Circuit X.25 LAN Protocol SS An Introduction to X.25

3. OSI Reference Model Application Presentation Session Transport Network Data Link Physical1 2 3 4 5 6 7 X.25 Protocol X.25 LAPB Physical1 2 3 X.25 Protocol Stack

4. Data Network ID Code Network Terminal Number 4 decimal digits Up to 10 or 11 decimal digits X.25 (X.121) Addressing Format Addressing set by service provider

5. X.25 IP Network IP Datagram X.25 Header Data-Link Frame (LAPB) X.25 Encapsulation Protocol datagrams are reliably carried inside X.25 frames

6. Switched Virtual Circuits (SVCs) Permanent Virtual Circuits (PVCs) X.25 Virtual Circuits Numbering for up to 4095 VCs per X.25 interface

7. X.25 Configuration Example interface serial 1 encapsulation x25 x25 address 311082194567 ip address 10.60.8.1 255.255.248.0 x25 map ip 10.60.8.2 311082191234 broadcast Cisco A interface serial 0 encapsulation x25 x25 address 311082191234 ip address 10.60.8.2 255.255.248.0 x25 map ip 10.60.8.1 311082194567 broadcast Cisco B IP Address: 10.60.8.2 X.121 Address: 311082191234 S1 X.25 IP Address: 10.60.8.1 X.121 Address: 311082194567 Cisco ACisco B S0

8. X.25 Local and XOT Switching x25 route [ # position ] x.121-address [ cud pattern ] interface type-number Router(config)# X.25 PAD Local Switching Remote Switching IP Internetwork X.25 PAD

9. Frame Relay Overview

10. Virtual circuits make connections Connection-oriented service DTE or CPE router Frame Relay works here. CSU/DSU DCE or Frame Relay Switch

11. Frame Relay Terminology Local Access Loop=T1 DLCI=400 DLCI=500 LMI 500=Active 400=Active Local Access Loop=64 kbps Local Access Loop=64 kbps

12. Frame Relay Terminology (cont.) BECN FECN I am congested. CIR=64 kbps T1 B c =32 kbps

13. Selecting a Frame Relay Topology Star (Hub and Spoke) Full Mesh Partial Mesh

14. Multipoint Subinterfaces Configuration Example RTR1 RTR3 RTR2 RTR4 s2.1=10.17.0.2/24 s2.2=10.17.0.1/24 s2.1=10.17.0.4/24 s2.1=10.17.0.3/24

15. Multipoint Subinterfaces Configuration Example ! interface Serial2 no ip address encapsulation frame-relay ! interface Serial2.2 multipoint ip address 10.17.0.1 255.255.255.0 bandwidth 64 frame-relay map ip 10.17.0.2 120 broadcast frame-relay map ip 10.17.0.3 130 broadcast frame-relay map ip 10.17.0.4 140 broadcast ! router rip network 10.0.0.0

16. Point-to-Point Subinterfaces Configuration Example RTR1 RTR3 s2.1 RTR2 RTR4 s2.2 s2.3 s2.4 s2.1 10.17.0.0/24 10.18.0.0/24 10.20.0.0/24

17. Point-to-Point Subinterfaces Configuration Example interface Serial2 no ip address encapsulation frame-relay ! interface Serial2.2 point-to-point ip address 10.17.0.1 255.255.255.0 bandwidth 64 frame-relay interface-dlci 110 ! interface Serial2.3 point-to-point ip address 10.18.0.1 255.255.255.0 bandwidth 64 frame-relay interface-dlci 120 ! interface Serial2.4 point-to-point ip address 10.20.0.1 255.255.255.0 bandwidth 64 frame-relay interface-dlci 130

18. Common LAN Technologies

19. Ethernet Token Ring FDDI LAN Technology Overview FDDI Dual Ring

20. Ethernet and IEEE 802.3 Several framing variations exist for this common LAN technology

21. Ethernet Frame Variations Ethernet Frame 802.3 Frame Preamble DA SA Type Data FCS 86624 Preamble DA SA Length 802.2 Header and Data 802.2 Header and Data FCS 86624

22. DSAP SSAP CTRL AA CTRL OUI Ether Type Ether Type Upper Layer Data IP, AppleTalk Upper Layer Data IP, AppleTalk DATA Ethernet Frame Variations 802.3 Frame Preamble DA SA Length 802.2 Header and Data 802.2 Header and Data FCS 802.2 Frame SNAP Frame

23. High-Speed Ethernet Options 100BaseTX 1000BaseT/SX/LX/LH/ZX

24. Token Ring and IEEE 802.5 IBM’s Token Ring is equivalent to IEEE 802.5 Token Ring

25. Physical Layer: Token Ring/802.5 Logically a ring, but physically a star configuration to MAU relays Shielded or Unshielded Twisted-Pair MSAU Logical Topology

26. The Token Ring/802.5 Interface Cisco router’s data link to Token Ring/802.5 uses interface named To plus a number (for example, To0) To0 Token Ring

27. Token Ring/802.5 Operation Token Ring LANs continuously pass a token A T = 0 TT

28. Token Ring/802.5 Operation Token Ring LANs continuously pass a token or a Token Ring frame A T = 1 A T = 0 TT TTDataData

29. Token Ring/802.5 Operation Token Ring LANs continuously pass a token or a Token Ring frame A T = 1 A T = 0 TT A TT TTDataData

30. Token Ring/802.5 Media Control Fields in a frame determine priority and reservation for sharing media T P M R Priority bits Reservation bits Monitor bit Token bit Access Control Field P P P P P P T T M M R R R R R R

31. FDDI Devices on FDDI maintain connectivity on dual counterrotating rings 100 Mbps FDDI Dual Ring

32. When a failure domain occurs... FDDI Dual-Ring Reliability

33. When a failure domain occurs...

34. FDDI Dual-Ring Reliability When a failure domain occurs......wrap primary and secondary rings......wrap primary and secondary rings......maintaining network integrity

35. ATM

36. ATM Basics Review A compromise for voice, data, and video Hardware-based cell relay Larger frames are segmented and reassembled at ATM endpoints Can span both LAN and WAN Scales from a few Mbps to multi-Gbps QoS defined/negotiated when initial connection is made Voice Video Data ATM cells 48-octet Payload ATM 53-octet cells are switched in hardware

37. ATM Cell Processing TCP IP LLC/SNAP AAL 5 ATM PHY Convergence Sublayer SAR Sublayer App DataTCP Header App DataTCP Header App DataTCP Header IP Header App DataTCP Header IP Header LLC TCP Packet IP Datagram AAL5-PDU AAL5 SAR-PDU - 48 Bytes ATM Hdr 5 Bytes Transmission Convergence (STS3c, STM-1, DS3, 4B/5B,...) Physical Media (MMF, SMF, STP, UTP, Coax, …) 48 Bytes 53 Bytes ATM Cell

38. Virtual Path and Virtual Channel ATM Physical Link Virtual Channel Connection (VCC) Virtual Path (VP) Contains Multiple VCs Virtual Channel Connection (VCC) Contains Multiple VPs VC Logical Path between ATM End points Virtual Channels (VCs) e.g., OC-3, E3, OC-12 Virtual Path (VP) VPI/VCI Connection Identifier = VPI/VCI

39. Well-Known VPI/VCIs VPI/VCI (Logical) x/5 x/16 x/18 Default (Physical) 0/5 0/16 0/18 Type Signaling ILMI PNNI Terminating Connections

40. ATM Cell Header— UNI Format VPI VPIVCI PTCLP HEC 8765432187654321 1234512345 Bits Bytes GFC VPIVCIPTCLPHEC 32 Bits8 Bits CRC 816318 GFC 4 PT User data or maintenance flow Congestion experienced End of message (AAL5)

41. ATM Cell Header—NNI Format VPI VPIVCI PTCLP HEC 8765432187654321 1234512345 Bits Bytes VPIVCIPTCLPHEC 32 Bits8 Bits CRC 1216318 Larger VP field for trunking Distinction not very useful for private network

42. VP Switching/VP Cross-Connect VCI 1 VCI 2 VCI 3 VCI 4 VCI 5 VCI 6 VCI 3 VCI 4 VCI 5 VCI 6 VCI 1 VCI 2 VPI 1 VPI 2 VPI 3 VPI 4 VPI 5 VPI 6 VP Switch Switching based on VPI only (central office trunk switching)

43. VP and VC Switching VCI 1 VCI 2 VCI 3 VCI 4 VC Switch VCI 1 VCI 2 VCI 1 VCI 2 VP Switch VPI 1 VPI 3 VPI 2 VPI 1 VPI 4 VPI 3 VPI 5 VPI 2 VCI 4 VCI 3 VCI 1 VCI 2

44. ATM Switch Translation Table ATM switches translate VPI/VCI values VPI/VCI value unique only per interface— e.g., locally significant and may be reused elsewhere in network 4/55 2/393 2 16/642/39 4/55 6/64 2/89 1 2 1 3 2/39 2/89 6/64 2 1 3 1 VPI/VCIPortVPI/VCIPort InputOutput

45. ATM Adaptation Layer Service Categories Bit RateConnection Mode Timing Concern Application Examples Bandwidth and throughput guaranteed Good for voice and video AAL1CBR (Constant) Connection- Oriented Yes Best effort bandwidth and throughput Good for live video, multimedia, LAN-to-LAN AAL2VBR (Variable) Connection- Oriented Yes Best effort with congestion feedback Reliable delivery of bursty traffic if latency okay AAL5ABR UBR VBR (CBR) Connection- Oriented No No guarantee For SMDS AAL3/4UBR (Un- specified) Connection- less No ATM Adaptation Layer (AAL) ATM Adaptation Layer (AAL) ATM Layer Physical Layer

46. AAL5 CS trailer Length CRC-32 Cell header Type: empty, not EOM, EOM Payload: 48 bytes Primary AAL for data Convergence Sublayer (CS) SAR Sublayer Convergence Sublayer PDU Payload Frame Data Frame AAL5 ATM Layer SAR PDU ATM Cell0x0 ATM Cell 0x0 0x1

47. AAL5—Frame and Cell Formats AAL5 CPCS - PDU Frame = n x 48 bytes 0-65535 bytes Payload Length CRC-32 Control (CPI and UU) 4 bytes 2byte 2 bytes PADPAD CPICommon part indicator, current function: aligning the trailer to 8 bytes, currently unused and set to 0 UUUser-to-user indication, currently unused and set to 0 PAD0-47 bytes AAL5 CPCS PDU Trailer User Data AAL5 SAR PDU = 1 Cell Payload SAR-PDU Payload = 48 bytes 53 = 5 (cell header) + 48 (payload) 0-47 bytes

48. ATM Signaling, ATM Address Formats

49. Switched Virtual Channels (SVCs) SVC requires signaling ATM connection oriented ATM Forum UNI 3.x/4.0 signaling specification Based on ITU-T Q.2931 B-ICI UNI NNI Public ATM Network Private ATM Network

50. Signaling Concept Signaling request Connection routed—setup path Connection accepted/rejected Data flow—along same path Connection teardown Connect to B OKConnect to B OK Connect to B OK ATM Router A ATM Router B

51. ATM SVC Call Setup Call set up in software Cell switching in hardware Dynamic call establishment (call setup) with appropriate parameters (e.g., QoS: CLR, CTD, CDV) Calling Party Called Party Setup Call Proceeding Connect ACK Connect Connect ACK Set Up Connect Connect ACK ATM Network ES

52. ATM SVC Call Release Calling Party Called Party Release Release Complete Release Release Complete ES ATM Network Dynamic call teardown (call release) of virtual connection

53. Q.2931 Call Control PD Call Ref Mes Type Mes Len Info Elements Q.2931 call control message format at UNI Q.2931 SSCOP

54. ATM Addressing Formats DSP AFI ICD AFI = 47 SELICDESI AFI E.164 AFI = 45 SELE.164 DSP ESI AFI DCC AFI = 39 SEL DCC DSP ESI AFI DCC DSP E.164 ESI HO-DSP ICD IDI Sel High-order Part of DSP International Code Designator Initial domain identifier NSAP Selector Authority and Format Identifier Data Country Code Domain Specific Part ISDN (telephone) Number End-system Identifier (IEEE)