ATM CONFIGURATION TUTORIAL
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ATM CONFIGURATION TUTORIAL

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28 Pages
English

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ATM CONFIGURATION TUTORIAL & EXPERIMENT ON ATM CONNECTIVITY BY ANANTH V. KINI MST SPRING 2001 1 ATM CONNECTIVITY The equipments to be used for this experiment are: 1. The CISCO Lightstream 1010 switch. 2. The Adtech AX/4000 tester. 1. The CISCO Lightstream 1010 switch: The CISCO LightStream 1010 uses a five-slot, modular chassis featuring the option of dual, fault-tolerant, load-sharing power supplies. (See Figure 1) The central slot in the LightStream 1010 is dedicated to a single, field-replaceable ATM switch processor (ASP) module that supports both the 5-Gbps shared memory and the fully non-blocking switch fabric. The ASP also supports the feature card and high performance reduced instruction set (RISC) processor that provides the central intelligence for the device. The remaining slots support up to four hot-swappable Carrier Modules (CAMs). Each CAM supports up to two hot-swappable Port Adapter Modules (PAMs) for a maximum of eight PAMs per switch, supporting a wide variety of desktop, backbone, and wide-area interfaces. Figure 1: Rear View of the LightStream 1010 ATM Switch The LightStream 1010 ATM switch ...

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 ATM CONFIGURATION TUTORIAL &
 EXPERIMENT ON ATM CONNECTIVITY
 
 
 BY
 ANANTH V. KINI
 MST
 SPRING 2001
 
 
 
 
 
 
 
 
 
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 ATM CONNECTIVITY The equipments to be used for this experiment are: 1.The CISCO Lightstream 1010 switch. 2.The Adtech AX/4000 tester.  1. The CISCO Lightstream 1010 switch: The CISCOLightStream 1010uses a five-slot, modular chassis featuring the option of dual, fault-tolerant, load-sharing power supplies. (SeeFigure 1) The central slot in the LightStream 1010 is dedicated to a single, field-replaceable ATM switch processor (ASP) module that supports both the 5-Gbps shared memory and the fully non-blocking switch fabric. TheASP also supports the feature card and high performance reduced instruction set (RISC) processor that provides the central intelligence for the device. The remaining slots support up to four hot-swappable Carrier Modules (CAMs). EachCAM supports up to two hot-swappable Port Adapter Modules (PAMs) for a maximum of eight PAMs per switch, supporting a wide variety of desktop, backbone, and wide-area interfaces.  
 Figure 1: Rear View of the LightStream 1010 ATM Switch TheLightStream 1010 ATM provides switched switchATMconnections to individual workstations, servers, LAN segments, or otherATM switches and routers using fiber-optic, unshielded twisted-pair (UTP), and coaxial cable. TheLightStream 1010 ATM switch can accommodate up to32 OC-3(155.52Mbps) switched ATM ports in a standard 19-inch (48-centimeter) rack.   
 
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                                            Figure 2: Adtech AX/4000
2.The Adtech AX/4000 tester: TheAX/4000 is a multi-port system that can currently test four different transmission technologies (IP, ATM, Ethernet, and Frame Relay) simultaneously at speeds up to10 Gbps.  Conceptually the experiment can be explained with the help of the following block diagram:   Lightstream 1010                                                                                                                                                                                     Port 1 Port 2      The 2 ports of the Adtech tester (ports 1 and 2) are connected to 2 different Port adapter modules (PAMswitch. In other words the AX/4000 simulates 2s) of the lightstream different end users that can communicate through the switch. Each physical layer connection to the switch is made using anOC-3 slot, i.e., theATMprotocol operates on a underlyingsonet physical layer.     VPI/VCI VPI/VCI  111111//111111                                              222222//222222 ATM interface          ATM interface  0/0/0 0/0/1   Figure 3: Cisco 1010 lightstream          
 
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                     Rx Tx                  Rx Tx                        VPI/ = 111   
                                                                                                                         
             ADTECH AX/4
     
              Tx Rx Tx Rx   PORT 1 PORT 2
  Before beginning the actual connectivity experiment we need to ensure that all the necessary connections already exist. TheLightstream 1010switch is connected to the ABCDE switch kept next to the pc, using a25 pin connector. The 25 pin cable is connected toport B of theABCDE data switch through theconsole port the of 1010.hence we need to switch the ABCDE switch to B when working on the 1010. Next we need to check whether the ports of the switch are up and running and properly connected to the corresponding ports of the Adtech Ax/4000 tester. You will be provided withfiber optic SC connectors.be 8m in length and you will need 2 pairs in They will total. Each pair provides a full duplex connection.  Cross-connect each pair between the port on theAX/4000 and a port on the Lightstream 1010. We cross-connect port1 on the Adtech tester toATMinterface 0/0/0 and port 2 on the Adtech tester toATMinterface 0/0/1. The connectors should easily slip
 
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into the ports. To remove the connectors just pull back the blue jacket at the end of the connector and slide the cable off.  When the switch for the ABCDE switch is on B pressing a carriage return will give the following prompt:     LS1010>  This shows that the pc is connected to theLighstream 1010switch, through the ABCDE switch.  Pressing?at any time will give you a list of all possible commands, pre-pending the? with a keyword gives all commands starting with that particular keyword. For example: the following typed at command line:         LS1010>sh atm vc ?  Will generate the following response:   interface Show ATM Connection Commands signaling Display ATM Interface Signaling information for all interfaces  traffic Display Virtual Channels Cell Traffic  cr> <  ending the above command with a carriage return will generate a list of all existing virtual channel connections, for e.g. something like the following:  LS1010>sh atm vc Interface VPI VCI Type X-Interface X-VPI X-VCI Encap Status ATM0/0/0 0 5 PVC ATM2/0/0 0 64 QSAAL UP ATM0/0/0 0 16 PVC ATM2/0/0 0 35 ILMI UP ATM0/0/0 0 200 PVC ATM0/0/2 0 200 DOWN ATM0/0/0 1 200 PVC NOT CONNECTED ATM0/0/0 105 105 PVC ATM0/0/1 205 205 UP ATM0/0/0 111 111 PVC ATM0/0/1 222 222 UP ATM0/0/0 200 200 PVC ATM0/0/2 200 200 DOWN ATM0/0/1 0 5 PVC ATM2/0/0 0 65 QSAAL UP ATM0/0/1 0 16 PVC ATM2/0/0 0 36 ILMI UP ATM0/0/1 205 205 PVC ATM0/0/0 105 105 UP ATM0/0/1 222 222 PVC ATM0/0/0 111 111 UP ATM0/0/2 0 5 PVC ATM2/0/0 0 66 QSAAL DOWN ATM0/0/2 0 16 PVC ATM2/0/0 0 37 ILMI DOWN ATM0/0/2 0 200 PVC ATM0/0/0 0 200 DOWN ATM0/0/2 200 200 PVC ATM0/0/0 200 200 DOWN ATM0/0/3 0 5 PVC ATM2/0/0 0 67 QSAAL DOWN ATM0/0/3 0 16 PVC ATM2/0/0 0 38 ILMI DOWN ATM0/1/0 0 5 PVC ATM2/0/0 0 68 QSAAL DOWN ATM0/1/0 0 16 PVC ATM2/0/0 0 39 ILMI DOWN ATM0/1/1 0 5 PVC ATM2/0/0 0 69 QSAAL DOWN ATM0/1/1 0 16 PVC ATM2/0/0 0 40 ILMI DOWN ATM0/1/2 0 5 PVC ATM2/0/0 0 70 QSAAL DOWN
 
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Consider for a moment the following line:  Interface VPI VCI Type X-Interface X-VPI X-VCI Encap Status ATM0/0/0 111 111 PVC ATM0/0/1 222 222 UP  This shows that the VPI/VCI pair 111/111 associated with ATM interface 0/0/0 is cross-connected to VPI/VCI pair 222/222 on interface 0/0/1 and that the link is up and running.  Also note theQSAALandILMInotations used under encapsulation.  The Lightstream 1010 usesILMI (Interim local management interface) to automatically identify which of its interfaces are User-Network Interface (UNI), attached to ATM end-systems, and which are Network-to-Network Interface (NNI), attached to other systems. It can also differentiate between private and public network links. This information discovers and brings up a network of interconnected LightStream 1010 switches. ILMI usesVC(0,16)as assigned by default.  TheQSAALis the link transport layer that provides reliable data delivery on the (0,5) signaling VC. The QSAAL layer is low level. Both these signaling functionalities are provided through the central processor located on the 1010 at interface2/0/0(VC starting from pair(0, 36)forILMIand(0, 65)forQSAAL.)  To obtain a detailed structure of a particularATMinterface (say interface 0/0/0) we need to type the following at the command line:  LS1010>show atm interface ATM 0/0/0  This will display something of the form: Interface: ATM0/0/0 Port-type: oc3suni IF Status: UP Admin Status: up Auto-config: enabled AutoCfgState: waiting for response from peer IF-Side: Network IF-type: UNI Uni-type: Private Uni-version: V3.0 Max-VPI-bits: 8 Max-VCI-bits: 14 Max-VP: 255 Max-VC: 16383 Svc Upc Intent: pass Signalling: Enabled ATM Address for Soft VC: 47.0091.8100.0000.0010.11b9.7801.4000.0c80.0000.00 Configured virtual links: PVCLs SoftVCLs SVCLs PVPLs SoftVPLs SVPLs Total-Cfgd Installed-Conns  6 0 0 11 0 0 17 9 Logical ports (VP-tunnels): 0 Input cells: 3468148935 Output cells: 39681577 5 minute input rate: 0 bits/sec, 0 cells/sec 5 minute output rate: 4000 bits/sec, 9 cells/sec Input AAL5 pkts: 373812, Output AAL5 pkts: 3271892, AAL5 crc errors: 1  As we can see this describes different details of the interface 0/0/0, for e.g. it shows that the port is anOC3 (sonet) user network interface of type private and version 3.0. it also specifies the max VPI/ VCI size and other useful parameters.  
 
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NOTE: It is important to remember the use of the ? key, it can be used at any time to obtain help for any command.  For additional information on theLightstream 1010you may refer to the CISCO page:  http://www.cisco.com/univercd/cc/td/doc/product/atm/ls1010s/11_1/sw_cg/index.h tm   We now move to the part where we generate cells on the ports and simultaneously receive cells on the same ports, these cells are intermediately switched through the lightstream 1010.  We can now begin the experiment on connectivity. In this experiment we essentially generate cells on port 1 of the adtech tester, these cells are transmitted toATMInterface 0/0/0(i.e., one of the 32 ports), using a pre-assignedPVC (VPI/VCI This) connection. traffic is then internally re-routed through the switch so as to be available onATM Interface 0/0/1 which is then transmitted to port 2 on theAdtechtester, once again using a pre-assignedPVC(VPI/VCI)connection.   The process to set upPVCconnections is described in the index under sectionA.2.4.  After creating the necessary connections, you can check the same using the following EXECmode command for e.g.:  show atm vc interface atmcard/sub_card/port vpi  vci This will generate all information regarding the connection created, for e.g. the cross-connect VPI/VCI and the interface for the PVC, whether the connection is up and running and other signaling and connection information. The details of all the relevant commands are given in the appendix.                
 
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We use the AX/4000 controller software installed on the pc. Given above is an example of the interface provided for the user. Thedistribution model is used to generate the type of cell sequence to be generated .one can choose periodic cells, periodic sequence or any one of the many distribution models available.  Thesequence definitionis used to define the type of sequence to be generated. In our case we just need to generate test cells and dont need to concern ourselves with OAM and signaling cells, so we choose one of the test cell sequences. We now need to specify the PVC (i.e. the VPI/VCI pair, which is done as described inA.2.4) over which the selected sequence is being transmitted. We do this by loading aPDU after we select the cell type/sequence type. An additional option is to select header error byte enable, which provides header error correction. We need not concern ourselves with the traffic shaping option. Theerror injectionoption can be used to randomly inject errors in selected bytes and analyze the same at the analyzer.  In theAnalyzerwe need to select the same option as the one chosen for cell type in generator. This option is provided insubstream setup.1. are only sending one We stream and hence are only concerned with the analyzed output for this substream. In addition we need select the PVC (i.e. select the VPI/VCI pair, this is chosen) chosen for this connection.  Once these connections are carried out we are ready to generate and analyze cells at theAdtechtester. This is done by observing thestatisticsboxes in the generator and analyzer windows. For additional information on the Adtech AX/4000 you may visit the Web page:http://www.adtech-inc.com/products/ax4000.asp                       
 
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APPENDIX   Contents:  A.1 :      Brief overview of ATM. A.2 :           A.2.1:   ATM Address configuration.  A.2.2:   Configuring the interfaces.           A.2.3:   Configuring network clocking.           A.2.4:   Configuring permanent virtual channel connections.           A.2.5:   Configuring terminating PVC connections.   ATM CONFIGURATION TUTORIAL  A.1 :  We begin with a brief overview of ATM: Asynchronous transfer mode (ATM) is a high-performance, cell-oriented switching and multiplexing technology that utilizes fixed-length packets to carry different types of traffic. Networks that have been primarily focused on providing better voice services are evolving to meet new multimedia communications challenges and competitive pressures. Services based on asynchronous transfer mode (ATM) and synchronous digital hierarchy (SDH)/synchronous optical network (SONET) architectures provide the flexibility essential for success in this market. Asynchronous transfer mode (ATM) can be viewed as an evolution of packet switching. Like packet switching for data (e.g., X.25, frame relay, transmission control protocol [TCP]/Internet protocol [IP]), ATM integrates the multiplexing and switching functions, is well suited for burst traffic (in contrast to circuit switching), and allows communications between devices that operate at different speeds. Unlike packet switching, ATM is designed for high-performance multimedia networking. ATM technology has been implemented in a very broad range of networking devices:  PC, workstation, and server network interface cards  switched-Ethernet and token-ring workgroup hubs  workgroup and campus ATM switches  ATM enterprise network switches  ATM multiplexers  ATMedge switches  ATMbackbone switches ATM is also a capability that can be offered as an end-user service by service providers (as a basis for tariff services) or as a networking infrastructure for these and other services. The most basic service building block is the ATM virtual circuit, which is an end-to-end connection that has defined end points and routes but does not have bandwidth dedicated to it. Bandwidth is allocated on demand by the network as users
 
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have traffic to transmit. ATM also defines various classes of service to meet a broad range of application needs. In ATM networks, all information is formatted into fixed-length cells consisting of 48 bytes (8 bits per byte) of payload and 5 bytes of cell header (seeFigure 1). The fixed cell size ensures that time-critical information such as voice or video is not adversely affected by long data frames or packets. The header is organized for efficient switching in high-speed hardware implementations and carries payload-type information, virtual-circuit identifiers, and header error check.
Figure 1: Fixed-Length Cells
 
 ATM is connection oriented. Organizing different streams of traffic in separate calls allows the user to specify the resources required and allows the network to allocate resources based on these needs. Multiplexing multiple streams of traffic on each physical facility (between the end user and the network or between network switches) combined with the ability to send the streams to many different destinationsenables cost savings through a reduction in the number of interfaces and facilities required to construct a network. ATM standards defined two types of ATM connections: virtual path connections (VPCs), which contain virtual channel connections (VCCs). A virtual channel connection (or virtual circuit) is the basic unit, which carries a single stream of cells, in order, from user to user. A collection of virtual circuits can be bundled together into a virtual path connection. A virtual path connection can be created from end-to-end across an ATM
 
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network. In this case, the ATM network does not route cells belonging to a particular virtual circuit. All cells belonging to a particular virtual path are routed the same way through the ATM network, thus resulting in faster recovery in case of major failures. An ATM network also uses virtual paths internally for the purpose of bundling virtual circuits together between switches. Two ATM switches may have many different virtual channel connections between them, belonging to different users. These can be bundled by the two ATM switches into a virtual path connection. This can serve the purpose of a virtual trunk between the two switches. This virtual trunk can then be handled as a single entity by, perhaps, multiple intermediate virtual path cross connects between the two virtual circuit switches. Virtual circuits can be statically configured as permanent virtual circuits (PVCs) or dynamically controlled via signaling as switched virtual circuits (SVCs). They can also be point-to-point or point-to-multipoint, thus providing a rich set of service capabilities. SVCs are the preferred mode of operation because they can be dynamically established, thus minimizing reconfiguration complexity. ATM Classes of Services ATM is connection oriented and allows the user to specify the resources required on a per-connection basis (per SVC) dynamically. There are the five classes of service defined for ATM (as per ATM Forum UNI 4.0 specification). The QoS parameters for these service classes are summarized inTable 1.  
Service Class Quality of Service Parameter constant bit rate This class is used for emulating circuit switching. The cell rate is (CBR) constant with time. CBR applications are quite sensitive to cell-delay variation. Examples of applications that can use CBR are telephone traffic (i.e., nx64 kbps), videoconferencing, and television. variable bit This class allows users to send traffic at a rate that varies with time ratenon-real depending on the availability of user information. Statistical time (VBR multiplexing is provided to make optimum use of network resources. NRT) Multimedia e-mail is an example of VBRNRT. variable bit This class is similar to VBRNRT but is designed for applications that ratereal time are sensitive to cell-delay variation. Examples for real-time VBR are (VBRRT) voice with speech activity detection (SAD) and interactive compressed video. available bit rate This class of ATM services provides rate-based flow control and is (ABR) aimed at data traffic such as file transfer and e-mail. Although the standard does not require the cell transfer delay and cell-loss ratio to be guaranteed or minimized, it is desirable for switches to minimize delay and loss as much as possible. Depending upon the state of congestion in the network, the source is required to control its rate. The users are allowed to declare a minimum cell rate, which is guaranteed to the connection by the network.
 
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