ATM Product Description -------Table of Contents-------------------------------- 1. Introduction 1.2 Service Overview 1.3 Traffic Usage Parameters 1.4 Interfaces 1.5 Performance and Quality of Service (QOS) 1.51 Service Availability 1.52 Accuracy 1.53 Delay 1.6 Addressing and Routing 1.7 Rate Elements PACIFIC BELL NETWORK DISCLOSURE For additional information --------------------------------------------------------- ATTACHMENT ATM Product Description 1. Introduction ATM service is a high-speed, connection oriented transport service. ATM service will be implemented by using Asynchronous Transfer Mode (ATM) technology. ATM is the switching and multiplexing technique chosen by CCITT for Broadband ISDN (B-ISDN). ATM service is designed to support a broad range of constant and variable bit rate applications, including video, image, high-speed data and multimedia. 1.2 Service Overview ATM service will provide connectivity among distributed customer sites. It provides for sequencing preserving, connection-oriented transfer of ATM cells between source and destination sites with an agreed upon quality of Service (QOS). Access from customer sites will be provided at DS-3 (44.736 Mbps) and OC3c (155.52 Mbps - optical) rates. ATM service is designed to provide simultaneous support for bursty traffic (data applications) and constant bit rate applications (video and audio applications). It also provides scalability, so that minimal capital investment is needed for equipment upgrades as bandwidth requirements increase. Permanent Virtual Connection (PVC) ATM - The Phase I service offering will be based on PVCs. No dynamic call establishment or call termination is associated with a PVC. With PVC ATM, connections are relatively static and are established through a provisioning process. A PVC is assigned at the point of ingress on the ATM network to the point of egress on the ATM network. PVCs are established in software tables at the time the customer subscribes to a PVC thus the communication path between endpoints is pre-established, and no connection set-up procedures are required. Connection Type -ATM connections are classified as either Virtual Channel Connections (VCCs) or Virtual Path Connections (VPCs). A Virtual Channel (VC) link exists between two switching points and is defined by the routing information obtained by the concatenation of the Virtual Path Identifier (VPI) and Virtual Channel Identifier (VCI) fields (3 octets) of the ATM cell header at the User-Network Interface (UNI). A VCC is the end-to-end concatenation of VC links. The VPI and VCI fields are assigned by the network when the VCC is provisioned. Initially, Pacific Bell is limited to supporting VC's (with 12 bit VCI's and VPI =0). A Virtual Path Connection (VPC) is a collection of VCCs routed together as one unit in which the customer has the ability to manage the attributes of the individual VCCs within a contracted or predetermined aggregated limit and offers the potential for more efficient management of bandwidth. A Virtual Path (VP) link is defined by the routing information contained in the VPI field (1 octet) of the ATM cell header. A VPC is the end-to-end concatenation of VP links. In this case the user can define individual VCCs comprising the VPC by assigning the VCI field (2 octets) in the ATM cell header. These user assigned VCIs will be delivered, unchanged, by the network and thus have end-to-end significance within a VPC. In a multimedia application, for example, video, audio, and data could be transported in separate VCCs within the same VPC. Since all VCCs in a VPC are routed along the same path through the network, the VCCs will experience similar delays. This is a useful feature for synchronization of associated channels. The initial offering will provide for the establishment of PVCs between multiple customer sites. Many PVCs can be established over a given access line, thus providing simultaneous logical connections to many remote locations. The following connection topologies are defined in TA- NWT-001110: Point-to-point: A point-to-point connection is a bi- directional communications connection between two endpoints. Asymmetric bandwidth is supported between endpoints. Point-to-Multipoint: A point-to-multipoint connection is unidirectional communication from a root node to multiple leaf nodes. An ATM cell stream sent by the root node is copied by the network and delivered to each of the leaf nodes. The leaf nodes do not need to be serviced by the same UNI. Asymmetric bandwidth allocation is supported with the broadcast bandwidth allocated in the root to leaf direction for all leaf nodes. Caution: If the customer wants bi-directional ATM Point- to-Multipoint service, a separate VC will be needed to be established in the leaf to root direction if the application requires that the leaf node source be identified. 1.3 Traffic Usage Parameters The PCR (Peak Cell Rate) is defined as the maximum instantaneous burst rate of any PVC. 1.4 Interfaces ATM will provide via the Broadband-ISDN User to Network Interface (UNI) as defined by the ATM Forum and Bellcore at DS-3 and OC-3c rates. Information will be transmitted in ATM cells across the interface. The nominal maximum number of PVCs per UNI is: UNI Total # of VCC's DS-3 1024 OC-3c 1024 1.5 Performance and Quality of Service (QOS) The performance of ATM for a PVC is defined collectively by a set of performance parameters, discussed below, encompassing service availability, information transfer accuracy, and information transfer delay. Each PVC will be assigned to QOS Class I (guaranteed traffic with stringent cell loss, cell delay, and cell delay variation objectives). QOS Class I is distinguished form QOS Class II (best effort traffic) by stricter cell loss and cell delay variation objectives. QOS Class I was designed to support demanding higher layer services such as real-time, full-motion compressed video and associated audio. The Phase I offering of ATM service will only include a single QOS level. Subsequent releases will augment this offering. 1.51 Service Availability Availability is the long-term average of the ratio of actual service time to scheduled service time on a per PVC basis. The scheduled time will be 24 hours per day, seven days a week. PVC ATM availability objectives apply UNI-to-UNI. The service availability objectives are heavily dependent on whether diverse routing is used in the access line between the end user and Pacific Bell's network. For the sake of simplicity, the service objectives are presented assuming no diverse facility routing: o For a PVC, the long-term service availability objective is 99.964 %; o The Mean Time Between Failure (MTBF) objective is no less than 2299 hours; o The Mean Time to Restore (MTTR) objective is no more than 2 hours. 1.52 Accuracy Cell Loss Ratio is defined as the number of cells lost in a given time interval to the total number of cells transmitted in that time interval on any single PVC. The Cell Loss Ratio objective for QOS Class I is less than 1 x 10 9. 1.53 Delay Transit delay over a PVC is defined by two parameters, the Cell Transfer Delay and Cell Delay Variation. Cell Transfer Delay is defined as the time from when the first bit in a cell enters the network at the UNI to when the last bit in the cell exits the network at the destination UNI. The Cell Transfer Delay objective is 99% of all cells in a PVC should experience delay less than 4.0 ms plus the propagation delay of the connection, which can be estimated as 2 x Air Miles x 1ms/100 miles. Cell Delay Variation is a relevant parameter for time sensitive traffic. Cell Delay Variation (CDV) is the time delay between the receipt of two successive cells minus the nominal (mean) time delay. The long-term objective for ATM is as follows: o The mean CDV for any PVC should be within +/- 0.01 ms of zero; o The 99% of CDV should be less than 0.5 ms; and o No more than 1 in 109 cells should experience CDV of more than 1.0 ms. 1.6 Addressing and Routing PVC based ATM does not require a public numbering plan. The source and destination points of a PVC are predefined through the service order/provisioning process, and are fixed for the duration of the connection. Thus, PVC-based ATM requires one locally significant address at each end to represent the desired destination(s). 1.7 Rate Elements Phase I ATM service will use a minimum of rate elements to simplify the provisioning process and provide maximum flexibility of the service for the end users. Both the Access and Network components will be provided for ATM Phase I. Access refers to the access transport service to Pacific Bell's network and Network refers to the switching service provided wit Pacific Bell's network. Both the Access and Network components will have two associated USOCs for two speeds supported (DS-3 and OC3c). The Access USOCs will be "zero rated" and all charges will be associated with Network USOC. Customer applications will use PVCs (Permanent Virtual Circuits) to allocate the appropriate amount of bandwidth for their requirements. There will be no charge for PVCs because they will be provided as part of the Network charge. The only other charge element will be the change charge. The change charge will provide for all customer changes identified per request. For example, if customer A requests the establishment of 5 new PVCs on a single ATM physical line, that change will be made for one change charge. If customer B request the establishment of 1 PVC and after two weeks makes another request to modify the Peak Cell Rate (PCR) for that new PVC, the customer will be charged for two changes. Submission for "Eye on the Regional Companies" - Bellcore Digest PACIFIC BELL NETWORK DISCLOSURE Asynchronous Transfer Mode Cell Relay Service Asynchronous Transfer Mode Cell Relay Service (ATM/CRS) provides wide are, high speed information transfer among distributed customer sites. CRS is a connection- oriented, cell-based transport service which can be offered on a broadband ATM platform. CRS transfers ATM cells between end-users over assigned Virtual Connections (VCs). These connections can be either Permanent Virtual Connections (PVCs), managed via administrative procedures, or Switched Virtual Connections (SVCs) which are established by the customer on demand. Based upon ATM/SONET Technology, Pacific Bell plans to deploy an Asynchronous Transfer Mode Cell Relay Service (ATM/CRS) delivering fiber connections to customers in the Bay Area (4Q/1993) and Los Angeles (1Q/1994) service areas initially. The early implementations are as follows: o PVC o Intra-LATA o DS-3 ATM User-to-Network Interface (UNI) o STS-3c ATM UNI In 1995 timeframe, implementations will include: STS- 12c, Inter-LATA connections and SVC, and additional service area expansion. The specifications to support the ATM/CRS services are as follows: o ATM Forum ATM User-Network Interface Specification Version 2.0, June 1, 1992 o Bellcore TA-NWT-0011100, Broadband ISDN Switching System Generic Requirements, Issue 1, August 1992 o Bellcore TA-NWT-001112, Broadband-ISDN User to Network Interface and Network Node Interface Physical Layer Generic Criteria, Issue 1, Aug. 1992 o Bellcore TA-NTWT-001113, Asynchronous Transfer Mode (ATM) and ATM Adaptation Layer (AAL) Protocols Generic Requirements, Issue 1, August 1992 The detailed Interface Specifications will be described in the Pacific Bell document: PUB L-780028-PB "Pacific Bell ATM/CRS User-to-Network Interface Specification" in December, 1993. To order this document, please contact: Pacific Bell Information Exchange 2600 Camino Ramon, Room 1S450S, San Ramon, CA. 94583 (510)823-0222 For additional information; concerning the Pacific Bell ATM/CRS, please contact: Pacific Bell Product Manager 2600 Camino Ramon, Room 3S451, San Ramon, CA. 94583 (510)823-4733