Introduction to ATM NW 97_EMEA_314 1 Characteristics

Introduction to ATM NW 97_EMEA_314 1

Characteristics of ATM Voice Data Video Cells • Uses small, fixed-sized cells • Connection-oriented • Supports multiple service types • Applicable to LAN and WAN NW 97_EMEA_314 2

ATM Standards Now Ready Test Beds and Pilots 1991 Early Adopters 1992 ATM Forum Founded 1993 1994 UNI 3. 0 • Signalling • Traffic policing UNI 2. 0 • Cell format • Physical layers Small-Scale Production Networks Large-Scale ATM Internetworks 1995 1996 LAN Emulation IISP VTOA MPOA PNNI • Static ATM routing • SVC interoperability 1997 Traffic Management • Dynamic ATM routing • Available Bit Rate (ABR) ATM Forum Founders Cisco Systems Sprint Net/Adaptive Northern Telecom NW 97_EMEA_314 Signalling 4. 0 “Anchorage Accord” 3

ATM Reference Model ATM Adaptation Layer (AAL) ATM Layer Physical Layer NW 97_EMEA_314 4

ATM Reference Model Physical Layer ATM Adaptation Layer (AAL) Two Sublayers: • Transmission Convergence (TC) Framing ATM Layer Physical Layer HEC • Physical Media Dependent (PMD) Physical media coding NW 97_EMEA_314 5

ATM Transmission Media ATM SDH/SONET Rates Chart SDH SONET Rate—Mbps STS-1/OC-1 51. 84 STM-1 STS-3/OC-3 155. 52 STM-4 STM-8 STM-16 STS-12/OC-12 STS-24/OC-24 STS-48/OC-48 622. 08 1, 244. 16 2, 488. 32 • CCITT (Consultative Committee for International Telephony and Telegraph) • ITU (International Telecommunications Union) NW 97_EMEA_314 6

Physical Layer Framing ATM Adaptation Layer (AAL) Data Rate (Mbps) Physical Layer DS 3 E 4 45 34 139 ATM 25 STS 1 STS 3 c/STM 1 STS 3 c/ 25. 6 51. 8 155 STP (TP) 622 100 155 = Standardized NW 97_EMEA_314 Multi- Single- Coaxial UTP– 5 UTP– 3 Multi. Mode Cable Fiber 1. 544 2. 048 6. 23 STS 12 c/STM 4 4 B/5 B (TAXI) 8 B/10 B (Fiberchannel) ATM Layer DS 1 E 1 J 2 Media (TP) X X X = Proposed/In Progress Proposed/ 7

ATM Reference Model ATM Layer ATM Adaptation Layer (AAL) ATM Layer • Cell header insertion/removal • Cell Relay • Multiplexes/demultiplexes cells of different connections Physical Layer NW 97_EMEA_314 8

Creating Cells from Packets Packet Dest. Address Source Address Frame Check Data SAR Segmentation and Reassembly Cells Header Payload Header 5 Byte Header 53 Bytes 48 Byte Payload Segmentation Happens at Source Payload Header Reassembly Happens at Destination Payload Header Payload ATM Cell NW 97_EMEA_314 9

ATM Cell Header 5 Byte Header 53 Bytes 48 Byte Payload ATM Cell NW 97_EMEA_314 10

ATM Cell Header Details GFC (4) GFC VCI (16) PTI CLP HEC 48 Byte Payload ATM UNI Cell NW 97_EMEA_314 VPI (12) VPI (8) Generic Flow Control UNI Cells Only! VPI/VCI Identifies Virtual Paths and Channels PTI Payload Type Identifier 3 Bits: 1. User/Control Data 2. Congestion 3. Last Cell CLP HEC Cell Loss Priority Bit Header Error Check 8 Bit CRC VCI (16) PTI CLP HEC 48 Byte Payload ATM NNI Cell 11

ATM Switches Input Port VPI/VCI Output 45 Port VPI/VCI 1 29 2 45 1 29 1 64 3 29 1 2 64 29 64 ATM Switch 1 3 29 • ATM switch performs cell-relay using connection identifiers Virtual Channel Identifier (VCI) Virtual Path Identifier (VPI) • ATM layer in ATM switches translates VPI/VCI values • VPI/VCI value unique only per interface, may be re-used elsewhere in network NW 97_EMEA_314 12

Virtual Path and Virtual Channels (VC) ATM Physical Link Virtual Path (VP) E 1 E 3 STM-1 STM-4 Virtual Path (VP) Virtual Channels (VC) Virtual Channel Connection (VCC) or Virtual Path Connection (VPC) is end-to-end Virtual Path (VP) Contains Multiple VCs Virtual Channel (VC) Logical Path Between ATM End Points Connection Identifier = VPI/VCI NW 97_EMEA_314 13

VP and VC Switching VC Switch VCI 1 VCI 2 VPI 1 VP Switch VCI 3 VPI 3 VCI 4 Port 2 VPI 2 Port 1 VCI 2 VCI 1 VCI 2 VPI 1 VPI 3 VPI 4 VPI 5 Port 3 NW 97_EMEA_314 14

ATM Signalling Public UNI aka B-ICI Public ATM Network NNI UNI NNI Private ATM Network • UNI = User-to-Network Interface • NNI = Network-to-Network Interface • Cell header content varies depending on who’s talking to whom NW 97_EMEA_314 15

ATM Signalling: The UNI • UNI 3. 0 and UNI 3. 1—Provide SVC capability at the UNI 3. 0 and 3. 1 not interoperable because they use different data link signalling protocols: Q. SAAL vs. SSCOP • Sig 4. 0 Multicast Better Qo. S NW 97_EMEA_314 16

ATM Connection Types • PVC, SVC, and Soft PVC • Point-to-point and Multipoint NW 97_EMEA_314 17

Connection Types S 2 1 S 6 1 S 2 S 6 1 S 8 S 3 S 5 2 S 1 S 3 S 5 S 8 VC 2 S 4 2 S 7 S 4 S 7 Connectionless: Packet Routing Connection Oriented: Cell Switching • Path 1 = S 1, S 2, S 6, S 8 • VC = S 1, S 4, S 7, S 8 • Path 2 = S 1, S 4, S 7, S 8 • Data takes the same path and arrives in sequence • Data can take different path and can arrive out of order NW 97_EMEA_314 18

Permanent Virtual Circuit (PVC) Input Port VPI/VCI 1 29 3 45 2 52 4 15 1 64 3 29 29 A Output 3 29 1 1 2 B Port VPI/VCI 1 33 3 02 2 1 Output Port VPI/VCI 1 45 2 16 2 52 1 29 1 64 3 29 1 14 29 29 1 64 3 30 Input 3 3 2 45 3 15 64 3 64 15 4 Output 2 1 10 43 3 16 2 C 14 4 D 64 Input Output Port VPI/VCI 1 16 2 43 3 14 4 10 1 64 3 29 1 64 • VPI/VCI tables in network equipment updated by administrator NW 97_EMEA_314 19

Switched Virtual Circuit (SVC) Input Output Input Port VPI/VCI 1 29 3 45 Output Port VPI/VCI 1 29 3 45 1 64 3 29 3 A 29 1 64 3 29 1 64 1 UNI Signalling 4 2 1 NNI Signalling 3 UNI Signalling 3 B C 3 Input Output Port VPI/VCI 1 45 2 16 2 52 1 29 1 64 3 29 1 64 2 2 1 4 D Input Output Port VPI/VCI 1 16 2 43 1 64 3 29 1 64 • Dynamically setup and tear down connections NW 97_EMEA_314 20

Soft PVC Input Output Input Port VPI/VCI 1 29 3 45 Output Port VPI/VCI 1 29 3 45 1 3 29 1 64 3 A 64 NNI Signalling 1 UNI Signalling C B Input Output Port VPI/VCI 2 52 1 29 1 64 3 29 1 1 2 Input Output Port VPI/VCI 1 16 2 43 64 D 1 64 3 29 1 64 • PVC established manually across UNI and dynamically across NNI NW 97_EMEA_314 21

Point-to-Point and Multipoint “Root” • Point-to-point Uni-directional or bi-directional traffic “Leaves” • Point-to-multipoint Uni-directional (root-to-leaves) only UNI 3. 1: Only Root can add leafs Sig 4. 0: Leaf Initiated Joins • Multipoint-to-point VC-Merge and Funnel Join NW 97_EMEA_314 22

ATM Reference Model ATM Adaption Layer (AAL) ATM Adaptation Layer (AAL) ATM Layer Physical Layer NW 97_EMEA_314 Two Sublayers: • Convergence Sublayer (CS) • Segmentation and Reassembly (SAR) 23

ATM Adaptation Layer—AAL ATM Adaptation Layer (AAL) ATM Layer AAL C S S A R Physical Layer AAL = CS + SAR • CS—assigns different AAL’s/Qo. S for different traffic types • SAR—cell <-> packet NW 97_EMEA_314 24

ATM Adaptation Layer Class ATM Adaptation Layer (AAL) A Bit Rate Connection Timing Service Categories Mode Concern AAL 1 AAL 2 C AAL 5 ATM Layer Physical Layer Connection. Oriented Yes • Bandwidth and throughput guaranteed • Good for voice and video VBR Connection. Oriented Yes • Best effort bandwidth and throughput • Good for live video, multimedia, LAN-to-LAN ABR Connection. Oriented No • Best effort with congestion feedback • Reliable delivery of bursty traffic if latency okay Connectionless No • No guarantee • For SMDS/LAN CBR (Constant) also VBR B (Variable) VBR-AT and VBR-NRT (Available) also UBR D NW 97_EMEA_314 AAL 3/4 Application Examples UBR (Un. Unspecified) 25

AAL • AAL criteria Traffic parameters Qo. S parameters • The AAL’s AAL 1—CBR AAL 2—VBR AAL 3/4—UBR AAL 5—ABR/UBR NW 97_EMEA_314 26

AAL Criteria Contract ATM Network Contract • Traffic Parameters Peak cell rate Sustainable cell rate Maximum burst size Minimum Cell Rate • Quality of Service Delay Cell loss NW 97_EMEA_314 27

AAL Criteria Traffic Parameters • Peak Cell Rate—PCR—Maximum data rate PCR a connection can handle without losing data • Sustainable Cell Rate—SCR—Average ATM SCR cell throughput the application is permitted • Maximum Burst Size—MBS—Size of the MBS maximum burst of contiguous cells that can be transmitted • Minimum Cell Rate—MCR—Rate of an MCR application’s ability to handle latency NW 97_EMEA_314 28

AAL Criteria Qo. S—Delay • Maximum Cell Transfer Delay—MCTD How long the network can take to transmit a cell from one endpoint to another • Cell Delay Variation Tolerance—CDVT Line distortion caused by change in interarrival times between cells aka jitter Qo. S—Cell Loss • Cell Loss Ratio—CLR Acceptable percentage of cells that the network can discard due to congestion NW 97_EMEA_314 29

ATM Quality of Service Guaranteed Service • Constant Bit-Rate (CBR) • Variable Bit-Rate (VBR) Real time (RT-VBR) Non-real time (n. RT-VBR) “Bandwidth-on-demand” Traffic contracts QOS guarantees NW 97_EMEA_314 Best Effort • Available Bit-Rate (ABR) • Unspecified Bit-Rate (UBR) No QOS guarantees Bursty, unpredictable traffic Need to minimize cell loss 30

Real Time Voice and Video The AAL’s AAL 1—Constant Bit Rate (CBR) also VBR Traffic Parameter Qo. S Tolerance PCR LOW HIGH Peak Cell Rate Cell Loss Cell Delay Overhead 5 Byte Header 1 Byte 47 Byte Payload NW 97_EMEA_314 31

Packetized Voice/Video, SNA Voice/Video, The AAL’s AAL 2—Variable Bit Rate (VBR-RT/VBR-NRT) Traffic Parameter Qo. S PCR Tolerance Peak Cell Rate LOW SCR HIGH Sustainable Cell Rate MBS Cell Loss Cell Delay (RT) Maximum Burst Size Cell Delay (NRT) Overhead 5 Byte Header 1– 47 Byte Payload NW 97_EMEA_314 1– 48 Bytes AAL 2 being updated 32

Public WAN—SMDS The AAL’s AAL 3/4—Unspecified Bit Rate (UBR) Traffic Parameter Qo. S Tolerance LOW No Guarantees Send and Pray HIGH Cell Delay Cell Loss Overhead 5 Byte Header 44 Byte Payload NW 97_EMEA_314 4 Bytes 33

LAN Interconnect for Data The AAL’s AAL 5—Available Bit Rate (ABR) also UBR Traffic Parameter Qo. S PCR Tolerance Peak Cell Rate MCR LOW HIGH Minimum Cell Rate Cell Loss Cell Delay Overhead 5 Byte Header 48 Byte Payload NW 97_EMEA_314 • No cell overhead • Uses congestion feedback instead H Last Cell Header has End of Message (EOM) Bit 34

A Day in the Life of a Cell ATM Payload Processing TCP Packet IP IP Datagram Convergence Qo. S + Sublayer (CS) AAL App Data IP Header TCP Header App Data LLC/SNAP TCP Header IP Header TCP Header App Data LLC IP Header TCP Header App Data Put in 48 Byte Cells—SAR into PDU Cells—SAR ATM PHY NW 97_EMEA_314 Add 5 Byte Headers with VPI/VCI and CLP Transmission Convergence (STS, STM, DS) Physical Media (MMF, STP, UDP, … 35

A Day in the Life of a Cell Traversing the Network ATM Switch A A L A T M UNI VPI 2 VCI 37 NNI NW 97_EMEA_314 A T M Port 1 P H Y VPI VCI 1 2 37 2 1 51 ATM Switch VPI 3 VCI 39 A A L A T M Port 2 P H Y Port 1 P H Y ATM Layer UNI A T M Port 2 P H Y ATM Layer Port VPI VCI 1 1 51 2 3 39 A T M 36

Traffic Management • Why traffic management? • Traffic control techniques • AAL 5/ABR congestion feedback • Buffers are your friend NW 97_EMEA_314 37

Why Traffic Management? • Proactively combat congestion • Provision for priority control • Maintain well-behaved traffic NW 97_EMEA_314 38

Why Traffic Management? Cell Loss—Data’s Critical Enemy Loss Ethernet (1500 Bytes) = 32 Cells FDDI (4470 Bytes) = 96 Cells IP over ATM– 1577 (9180 Bytes) = 192 Cells TCP/IP Packet X • Lose one cell and the rest are useless • Need to re-transmit 32+ cells for one cell lost • Congestion collapse is the result NW 97_EMEA_314 39

Traffic Control Techniques • Connection management—Acceptance • Traffic management—Policing • Traffic smoothing—Shaping NW 97_EMEA_314 40

Traffic Control Techniques Connection Management Connection Admission Control (CAC) I want a VC: X Mbps Y Delay Z Cell Loss CAC Can I Support this Reliably without Jeopardizing Other Contracts Guaranteed Qo. S Request No or Yes, Agree to a Traffic Contract ATM Network NW 97_EMEA_314 41

Traffic Control Techniques Traffic Management Usage Parameter Control (UPC) aka Policing Contract REBEL APPLICATION NW 97_EMEA_314 You are Not in Conformance with the Contract. What Should the Penalty Be? ? ATM Network ? DECISION? • PASS • MARK CLP BIT • DROP 42

Traffic Control Techniques Traffic Management UPC Marked 0 0 0 D r o p 0 1 0 ? DECISION? • PASS • MARK CLP BIT • DROP • CLP Control—When congested drop marked cells • Public UNI—Generic Cell Rate Algorithm (GCRA) NW 97_EMEA_314 43

Traffic Control Techniques Traffic Management UPC Marked 0 0 0 D r o p • • NW 97_EMEA_314 0 3 1 0 2 Intelligent Packet Discard—IPD Discard cells from same ‘bad’ packet Tail packet discard Maximize “Goodput” Goodput 44

Benefit of Packet Discard Switch without Packet Discard Switch with Intelligent Packet Discard NW 97_EMEA_314 45

Congestion Control Intelligent Tail Packet Discard ATM/Switch UPC 1 EOM X 0 6 7 5 4 Output Buffer 3 2 1 Early Packet Discard Output Queue EOM EPD Threshold NW 97_EMEA_314 46

Traffic Control Techniques Traffic Smoothing I Want to Comply With My Contract. So, I Will Smooth/Shape My Traffic Private ATM Network Shaper Actual Data Go Ahead, Make My Day Shaped Data Public ATM Network • Traffic shaper at customer site • Changes traffic characteristics • Leaky bucket algorithm NW 97_EMEA_314 47

Additional Congestion Control Available Bit Rate (ABR) Must Minimize Feedback Delay A Feedback B C NW 97_EMEA_314 Light. Stream Z Feedback Mechanisms Must be Integrated into Switch Hardware Light. Stream 48

Three ABR Schemes Explicit Rate Mode Efficiency Most Sophisticated Ideal for WAN Networks Relative Rate Mode Simple and Efficient Ideal Campus Networks EFCI Mode Backward Compatibility High Latency Strata. Com Switch Family Light. Stream 1010 Family Complexity/Cost NW 97_EMEA_314 49

Traffic Control Techniques AAL 5/ABR Congestion Feedback Forward EFCI Set X X Destination Source RM X Congestion Experienced Slow Down RM X Backward • EFCI Marking—Explicit Forward Congestion Indicator Congestion flag set on forward cells only Destination end-system sends RM cells back to source NW 97_EMEA_314 50

Traffic Control Techniques AAL 5/ABR Congestion Feedback Forward RM Destination Source RM X Congestion Experienced Slow Down Backward • Relative rate marketing Switches can set congestion flag in backward RM cells NW 97_EMEA_314 51

Traffic Control Techniques AAL 5/ABR Congestion Feedback Congestion Experienced Slow Down X Amount Forward RM Destination Source RM Congestion Experienced Slow Down Backward • Explicit rate marketing Switches can tell source at exactly what rate to transmit NW 97_EMEA_314 52

Traffic Control Techniques AAL 5/ABR Congestion Feedback Forward Congestion Experienced Slow Down Destination Source Backward • VS/VD—Virtual source/virtual destination Breaks the feedback loop into separate segments Shortens length of feedback loop NW 97_EMEA_314 53

Traffic Control Techniques Buffers Are Your Friend • Absorb traffic bursts from simultaneous connections • Switches schedule traffic based on priority of traffic according to Qo. S • Switch must reallocate buffers as the traffic mix changes • Effective buffering maximizes throughput of usable cells as opposed to raw cells (aka goodput) goodput NW 97_EMEA_314 54

ATM Addressing Formats • Public network will use E. 164 numbers AFI DCC E. 164 ESI DSP ICD SEL • ATM Forum defined new ATM private-network address formats: Modelled on NSAPs AFI DCC 39 AFI ICD NW 97_EMEA_314 45 High Order Part of DSP International Code Designator NSAP Selector ESI SEL ESI DSP SEL ESI SEL DCC ATM Address Format AFI ICD 47 Authority and Format Identifier Data Country Code ISDN (Telephone) Number (Telephone) End System Identifier (IEEE) DSP ICD ATM Address Format E. 164 DSP E. 164 ATM Address Format 55

Possible Addressing Plan level 56 Cisco ICD San Jose Main 47. 0091. 8000. 1122. 0001 cisco corporate network 47. 0091. 8000. 1122 San Jose South 47. 0091. 8000. 1122. 0002 level 72 Chelmsford 47. 0091. 8000. 1122. 0101 level 72 Building A 47. 0091. 8000. 1122. 0001. 01 Building O. . . 47. 0091. 8000. 1122. 0001. 0 F level 72 level 80 Building O, 1 st Floor 47. 0091. 8000. 1122. 0001. 0 F. 01 level 88 NW 97_EMEA_314 Building O, 2 nd Floor 47. 0091. 8000. 1122. 0001. 0 F. 02 level 88 56

Address Registration in ATM Goal: No Manual Configuration MAC Address (ESI) ATM Address Prefix ILMI MIB LECS Address Or ILMI Protocol UNI ATM End Station ATM Switch • Integrated Local Management Interface (ILMI) eliminates need for manual configuration—autoconfiguration • ATM end-point sends “SNMP format” queries • End Station Identifier (ESI) and hierarchical prefix included in ATM address NW 97_EMEA_314 57

ATM Routing What Is Path Determination? Destination Source • Traditionally router-based: Source • Now ATM switch-based: RIP IISP IGRP PPNI Phase 1 OSPF EIGRP NW 97_EMEA_314 58

IISP B Port 1 A UNI 3. 1/3. 0 for SVC Port 2 Destination Primary Secondary B Port 1 Port 2 • Interim Inter-switch Signalling Protocol (IISP) Static route defined in ATM switches Dynamic call setup via UNI signalling Suitable for small ATM networks NW 97_EMEA_314 59

PNNI A Routing Protocol PG PG PG • Distributes reachability and topology information between switches • Dynamic re-routing around failures • Routing for reachability based on OSPF • Peer groups are analogous to an OSPF area • PNNI allows hierarchical organization of network NW 97_EMEA_314 60

PNNI A Signalling Protocol Link B. 3–B. 6 does Not have Suffic B B. 2 A A. 2 A. 1 A. 3 B. 1 Re-Route C B. 3 Crank. Back C. 2 B. 6 C. 1 C. 3 Destination Source B. 4 B. 5 • PNNI—provides a path that satisfies the request Qo. S • Negotiates metrics such as Av. CR, MCTD, MCLR • Uses Connection Admission Control (CAC) • Uses Crankback for re-routing to alternate path NW 97_EMEA_314 61

PNNI Hierarchy An ATM Switch IF Card Switching Fabric IF Card A Group of Peer Groups PG Switch PG PG Switch IF Card NW 97_EMEA_314 IF Card A Group of ATM Switches (Peer Group) Switch PG Switch 62

ATM Internetworking • Challenges • RFCs 1483, 1577, and NHRP • LANE and MPOA • IP Multicasting • Quality of Service • Tag and MPLS NW 97_EMEA_314 63

ATM Internetworking The Challenges Existing and New Applications Network Address API New Applications MAC Address ? ? ? ATM Address • MAC address to ATM address resolution • No Standard ATM API NW 97_EMEA_314 64

ATM Internetworking Overlay Model ATM Addresses Router or Switch Ethernet Router or Switch ATM Network Ethernet Direct-Attached Stations Network Addresses, MAC Addresses • Multiple layers of addressing NW 97_EMEA_314 65

ATM Internetworking RFC 1483 Multiprotocol Encapsulation over ATM AAL 5 • Encapsulation method used by other protocols • Two methods: LLC/SNAP—(Logical Link Control/Sub-Network Access Protocol) VC Multiplexing—(Virtual Circuit Multiplexing) NW 97_EMEA_314 66

ATM Internetworking RFC 1483—Example Routing Table 138. 20. 1. 1 Address Resolution Table DA-138. 20. 10. 45 138. 20. 1. 2 ATM Network 138. 20. 10. X • Routing Table maps final destination to next hop network address • Address Resolution table maps next-hop network address to ATM address—setup manually by network administrator • NW 97_EMEA_314 Signalling creates ATM VC between routers 67

ATM Internetworking RFC 1577—Classical IP and ARP over ATM ARP Server Subnet 1 ATM Network LIS 1 ARP Server Subnet 2 LIS 2 • LIS—Logical IP subnet—an IP subnet • ARP Server—maintains IP address to ATM address mappings • One ARP Server per LIS • No cut-through to alleviate router hops NW 97_EMEA_314 68

ATM Internetworking RFC 1577—Example ARP Server Routing Table 138. 20. 1. 1 DA– 138. 20. 10. 45 138. 20. 1. 2 ATM Network 138. 20. 10. X • Routing table maps final destination to next-hop • ATM ARP Server maps next-hop IP address to ATM addresses • Signalling creates VC and data is passed NW 97_EMEA_314 69

Next Hop Resolution Protocol NHS 3 NHS 2 Next Hop Server NHRP Response NHS 1 NHS 4 ATM Network NHRP Query LIS 1 LIS 2 LIS 3 LIS 4 Direct Connection • Allows direct connections between LIS’s across cloud (LIS = Logical IP Subnet) • Next hop requests passed between Next Hop Servers (NHS) NW 97_EMEA_314 70

ATM Internetworking LANE 1. 0 ATM Network Today’s Physical LAN Segment • Hides ATM to upper layers Emulated LAN (ELAN) Segment • Makes ATM look like Ethernet/Token Ring • Supported in NICs, LAN switches, ATM routers • Allows ATM hosts connectivity with legacy LANs NW 97_EMEA_314 71

Why ATM LAN Emulation (LANE)? • Standards-based Virtual LAN (VLAN) support over ATM-attached hosts can be in several VLANs at once • No disruption to current protocols and applications • Integrates desktop LANs with ATM-attached servers Most users can stay on switched Ethernet or Token Ring • Evolution path Can utilize high-speed advantages of ATM now Can exploit ATM QOS and service integration benefits in future NW 97_EMEA_314 72

ATM Internetworking LANE—Basics LEC—LAN Emulation Client LECS—LAN Emulation Configuration Server for Initialization LES—LAN Emulation Server for Address Resolution ATM BUS—Broadcast and Unknown Server for Data Flooding • Uses SVC’s to establish conversations • Uses RFC 1483 to transport LAN traffic NW 97_EMEA_314 73

LAN Emulation TCP Native Mode Routing Protocols IP IP Virtual LANs (LAN Emulation) MAC ATM Routing (P-NNI Protocol) RFC 1483 Encapsulation Q. 2931 SSCOP AAL 5 ATM Phy ATM Host/Router NW 97_EMEA_327 MAC RFC 1483 Encapsulation Q. 2931 P-NNI UNI Signal- SSCOP NNI ing Convg AAL 5 P-NNI Q. 2931 NNI Signal- NNI SSCOP ing Convg ATM Phy ATM ATM Phy Phy Phy ATM Switch AAL 5 ATM Switch UNI Signaling Q. 2931 SSCOP AAL 5 ATM Host/Router 74

LANE—Fully Configured Cisco Specific LECS LES BUS Data Direct VCs NW 97_EMEA_314 75

RIP OSPF SA P ZIP F PF SP O O ARP P IP RI A R P Routing Contains Broadcasts/Multicasts Per Second SAP Broadcasts/Multicasts Per Second • Restores processor performance • Routes unicast between Virtual LANs NW 97_EMEA_314 76

LANE/VLAN Internetworking Within ELAN Between ELANs Layer 2 Switching ATM Switch NW 97_EMEA_314 ATM Router Layer 3 Switching 77

LUNIv 2 • Better efficiency Reduced VC consumption via optional LCC multiplexing Optional, more efficient distribution of multicast • Better use of ATM Qo. S ABR and signalling 4. 0 features Supports emerging IEEE 802. 1 q/p Class of Service (Co. S) • Used within MPOA • LNNI with redundancy still in-progress NW 97_EMEA_314 78

ATM Internetworking MPOA—Multi-Protocol over ATM • For seamless transport of layer 3 protocols across ATM networks MPC Resultant Direct Cut-Through between Cut. Different VLANs MPS • Goes beyond LANE by allowing direct ATM connectivity between hosts in different subnets • Architecture consists of edge devices and route servers • MPC—MPOA client— edge device • MPS—MPOA server— route server NW 97_EMEA_314 79

MPOA for Inter-VLAN “Cut-Through” 1. Initially packets routed between Emulated LANs (VLANs) 2. L 3 cut-through forwarding 3. Inter-VLAN traffic via resultant direc info given to edge devices Use this L 3 Cut-Through for Red to Blue NW 97_EMEA_314 Resultant Direct Cut-Through Between Red and Blue 80

MPOA Goals • Enable L 3 protocols to exploit ATM • Direct VCs between devices on different subnets Access to ATM QOS; L 3 -to-ATM QOS integration • Other MPOA goals Separate forwarding from route calculation functions Benefit: Lower-cost L 2/L 3 forwarders vs. a full router in LAN switches Require no changes in legacy-attached hosts Leverage/integrate work by other groups (e. g. LANE, IETF, IEEE) NW 97_EMEA_314 81

MPOA Service Basics (Phase 1) MPOA Server (MPS) Config Server Initialization (Uses LECS) Default Forwarder Connectionless Unicast Forwarding Route Server Address Resolution and Can Initiate the Forwarding of Info to MPOA Clients (MPC) NW 97_EMEA_314 82

MPOA—Query and Response MPOA Server MPOA Query and Response MPOA Server OSPF, EIGRP, etc Subnet A Emulated LAN A ATM Network Resultant Direct Cut-Through VC NW 97_EMEA_314 Subnet B Emulated LAN B Edge Devices 83

MPOA—Router Initiated ‘MPOA Trigger’ MPOA Server Use this L 3 Cut-Through MPOA Server for A to B MPOA Server OSPF, EIGRP, etc Subnet A Emulated LAN A ATM Network Subnet B Emulated LAN B Edge Devices NW 97_EMEA_314 84

MPOA: LAN or WAN? • Uses LANE for intra-VLAN connectivity • No Qo. S or granular IP Multicast support • Result: Less efficient use of WAN bandwidth • Options more suitable: RFC-1577/NHRP, Tag/MPLS, RFC-1483 bridging NW 97_EMEA_314 85

Approaches to ATM Multicast Server Meshed Point-to-Multipoint • Some applications require a “connectionless” multicast/broadcast service from ATM (e. g. ARP) • AAL 5 cannot handle intermixing of cells! NW 97_EMEA_314 86

PIM to ATM Flows Receives only selected video feeds PIM driven pt-mpt VCC for Group 1 Group 2 Headend Router PIM driven pt-mpt VCC for Group 2 pt-mpt VCCs for PIM info and routing updates (Static Map) NW 97_EMEA_314 Receives only requested feeds 87

Goal: Qo. S Support over ATM Backbone End-to-End Application QOS Request QOS Guarantee “Middleware” — Network Layer Protocols QOS Request et/ Token Ring Host Routers QOS Guarantee ATM Switches Ethernet/ Token Rin LAN Switching ATM Host NW 97_EMEA_314 88

Video over ATM Options Video Stream (MPEG, M-JPEG, H. 323, other) CBR UBR IP Circuit Emulation ATM AAL 5 Circuit Emulation NW 97_EMEA_314 UBR/ABR /VBR IP MAC Protocols ATM AAL 1 UBR/ABR /VBR LAN Emulation ATM AAL 5 ATM AAL 1/5 Native Mode Video over ATM 89

Benefits Large Routed Backbones Without Tag Switching With Tag Switching • Layer 2 ATM core with routers • Tag switching core with tag routers • Signalling performance issues • Tag switches are routing peers • All routers are neighbors • All packets tagged—per edge or prefix • 1 link failure = N 2 peer failures • Minimizes signalling overhead • Scalability is limited • Increased scalability NW 97_EMEA_314 90

Tag Switching Operation 1 a. Routing protocols determine reachability (e. g. OSPF, EIGRP) 1 b. Tag Distribution Protocol (TDP) assigns tags to destinations 2. Tag Edge Router (TER) applies tags to all packets NW 97_EMEA_314 4. Tag edge router removes tags and forwards 3. Packets tag switched through network 91

Tag Switching and QOS Overview • Qo. S-tag options Precedence tagging (Co. S) RSVP flows individually tagged • Qo. S-tag operation basics Initial packet Qo. S classification Video Traffic Elasticity FTP E-Mail Bandwidth Tag applied based on classification Tag switched through network NW 97_EMEA_314 92

Tag Switching and ATM Services Co-Existing on Same Platform! (Ships in Night) • ATM services for real-time services IP IP PNNI/UNI signalling Voice trunking ATM FR Circuit Emulation (CES) • Tag switching for data traffic FR IP Offloads signalling-intensive traffic Reduces call set-up dependencies NW 97_EMEA_314 93

Tag Switching Standardization • Multiprotocol Label Switching (MPLS) is the IETF working group for Tag Switching and similar proposals • Two main proposals - Tag Switching and ARIS - are very similar • Cisco is proceeding with Tag development now, software upgrades to full MPLS standard when it exists • Tag, ARIS, Internet-Drafts are widely available, anyone can implement them NW 97_EMEA_314 94

Voice Integration • Success of ATM will depend in part on fulfilling promise of multiservice integration • Migration of corporate and service provider voice to ATM backbone results in cost savings • Standards exist and hardware is becoming available • Looking forward, Voice and Telephony over ATM (VTOA) and Voice over IP will co-exist NW 97_EMEA_314 95

Voice Architecture Implements VTOA Interworking Voice Server (enables ‘Virtual’ PABX) E 1 ‘Legacy’ PABX Analog/Digital ATM (Campus or WAN) Implements VTOA Interworking NW 97_EMEA_314 ATM-connected PABX Implements VTOA 96

Security Options at Layers 2 and 3 Untrusted Host Problem: No Layer 3 Screening Possible Must implement screening Trusted Host ATM VCC Firewall Solution: Layer 3 Screening Possible IPsec will play an important role Closed User Groups and NSAP filtering a solution for closed communities (VPNs) NW 97_EMEA_314 97

The Wonderful World of Acronyms AAL—ATM Adaptation Layer AAL 1—See CBR AAL 1— AAL 2—See VBR AAL 3/4—See UBR AAL 3/4—See AAL 5—See ABR—Available Bit Rate ABR—Available API—Application Programmer Interface B-ICI—B-ISDN Inter-Carrier Interface Inter. BUS—Broadcast and Unknown Server CAC—Connection Admission Control CAC—Connection CBR—Constant Bit Rate CCITT—Consultative Committee for International Telephony and Telegraph CCITT—Consultative CDVT—Cell Delay Variation Tolerance CLP—Cell Loss Priority CLR—Cell Loss Ratio CS—Convergence Sublayer CS—Convergence EFCI—Explicit Forward Congestion Indicator ELAN—Emulated LAN ELAN—Emulated GCRA—Generic Cell Rate Algorithm GFC—Generic Flow Control GFC—Generic HEC—Header Error Check IISP—Interim Inter-Switch Signalling Protocol IISP—Interim Inter. ILMI—Interim Local Management Interface NW 97_EMEA_314 98

The Wonderful World of Acronyms IPD—Intelligent Packet Discard IPD—Intelligent LANE—Local Area Network Emulation LEC—LAN Emulation Client LES—LAN Emulation Server LECS—LAN Emulation Configuration Server LIS—Logical IP Subnet MBS—Maximum Burst Size MCR—Minimum Cell Rate MCTD—Maximum Cell Transfer Delay MPC—MPOA Client (aka Edge Device) MPOA—Multi-Protocol Over ATM MPOA—Multi. MPS—MPOA Server (aka Router Server) NNI—Network-to-Network Interface OC—Optical Carrier PCR—Peak Cell Rate PCR—Peak PMD—Physical Media Dependent PNNI—Private Network-to-Network Interface PNNI—Private PTI—Payload Type Identifier PVC—Permanent Virtual Circuit Q. SAAL—aka Q. 2100—Signalling ATM Adaptation Layer RFC 1483—Multiprotocol Encapsulation over AAL 5 RFC 1483— RFC 1577—Classical IP and ARP over ATM RM—Resource Management RM—Resource NW 97_EMEA_314 99

The Wonderful World of Acronyms SAR—Segmentation and Reassembly SDH—Synchronous Digital Hierarchy SDH—Synchronous SONET—Synchronous Optical Network STM—Synchronous Transport Mode STM—Synchronous STS—Synchronous Transport Signal SCR—Sustained Cell Rate SCR—Sustained SVC—Switched Virtual Circuit SSCOP—Signalling Specific Convergence Protocol SSCOP—Signalling TC—Transmission Convergence UBR—Unspecified Bit Rate UBR—Unspecified UNI—User-to-Network Interface UPC—Usage Parameter Control UPC—Usage VBR-NRT—Variable Bit Rate-Non-Real Time VBR-RT—Variable Bit Rate-Real Time VBR-RT—Variable Rate. VC—Virtual Circuit (or sometimes Virtual Connection) VCC—Virtual Channel Connection VCC—Virtual VCI—Virtual Channel Identifier VC Switch—Virtual Circuit Switch— VP—Virtual Path VPC—Virtual Path Connection VPC—Virtual VPI—Virtual Circuit Identifier VP Switch—Virtual Path Switch— VS/VD—Virtual Source/Virtual Destination NW 97_EMEA_314 100