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Asynchronous Transfer Mode (ATM) Service is a fast packet, cell-based technology that can support data and video applications requiring high bandwidth, high performance transport and switching. ATM Service will allow Customers who have requirements for high-speed connectivity to interconnect their multiple locations. ATM offers low latency, high throughput and flexible bandwidth interconnections capable of carrying a wide range of Services.


  • Bandwidth Efficiency
  • Flexibility and Scalability
  • Reliability
  • Application
  • Worldwide
  • Multiservice Networking
  • Works with Frame
  • DSL Backbone
  • Increased productivity

Service Components

  • User Network Interface (UNI) Port and Access
  • User Network Interface (UNI) Port Only
  • Inverse Multiplexing over ATM (IMA) UNI Port and Access
  • Inverse Multiplexing over ATM (IMA) UNI Port Only
  • Broadband ISDN Inter-Carrier Interface (B-ICI) Port and Access
  • Broadband ISDN Inter-Carrier Interface (B-ICI) Port Only
  • Circuit Emulation Service (CES) Port Only

Permanent Virtual Circuits (PVCs)
PVCs are logical connections between ports that allow data to be sent from one customer location to another. PVCs do not engage capacity when idle, allowing the available capacity to be allocated to other active PVCs that are in need of additional bandwidth. With the exception of multicasting VCCs, PVCs are duplex (two-way).

When placing an order for service, customer must specify the following for each PVC:

  • PVC Connection Type
  • Traffic Parameter
  • VCC/VPC Type, and
  • Quality of Service

ATM when purchased for DSL transport is only available as UBR quality of service.

PVC Connection Types
Frame Relay to ATM Service (FRATM)

Traffic Parameters
The Customer must choose the traffic parameters available for each PVC selected. Traffic parameters represent priorities given to cell transmissions, sensitivity of cells to delay variation and loss within the network. Traffic Shaping is a flow control functionality that must be enabled on the Customer Equipment to ensure the Customer's data traffic transmission rate does not violate the Customer's chosen traffic parameters.

Information Rate

Peak Information Rate (PIR) The PIR designates an upper limit that the traffic information rate may not exceed. PIR is expressed in Kbps or Mbps. Traffic that exceeds the PIR value will be discarded from the network for all Quality of Service types.

Sustainable Information Rate (SIR)
The Sustainable Information Rate (SIR) specifies the "average" traffic rate that is transmitted and received. SIR is expressed in Kbps or Mbps.

Maximum Burst Size (MBS)
MBS specifies the maximum number of cells per second (cps) that can be transmitted at the PIR. The MBS default is 32cps.

PVC Types

Virtual Channel Connection (VCC)
Logical connection between one ATM switch port and another switch port. The VCC allows exchange of information in the form of fixed cells at variable rates. Company configures and maintains the individual VCCs within the ATM connection.

Virtual Path Connection (VPC)
A group of logical connections between one ATM switch port and another ATM switch port. A VPC connection is typically used to route multiple Customer defined VCCs as a group. It is the responsibility of the Customer to configure and maintain the individual VCCs within a VPC connection.

There are several VCC/VPC types available, which may vary by region.

VPC Types

Standard VCC/VPC
Standard VCCs/VPCs are utilized in typical ATM networks to provide logical connections between two ports.

Circuit Emulation Service (CES) VCC
CES VCCs provide logical connection between an CES port and another ATM port. CES VCC is to be used in conjunction with CES Port Only. CES VCCs are always provisioned with CBR Quality of Service and a PIR traffic parameter of 1.755 Mbps. A CES DS1 VCC cannot be provisioned to an ATM DS1 UNI Port. CES VCCs are not available in all regions.

Frame Relay to ATM Service (FRATM) VCC
A FRATM VCC is established to connect two Customer locations, one having a Frame Relay port and the other an ATM port, to provide transparent interworking between Frame Relay and ATM networks. The FRATM VCC is provisioned with VBR-nrt Quality of Service on the ATM portion, and Standard Quality of Service on the Frame Relay portion. The FRATM VCC is priced based upon the ATM SIR value selected.

Disaster Recovery VCC
Disaster Recovery VCCs allow for the implementation of logical connections between branch locations and a secondary processor/server center (disaster recovery location) should a non-recoverable disaster occur at the primary host location. The disaster recovery location must also be served by an active, company provided ATM/Frame Relay Port. Disaster Recovery VCCs are provisioned based upon an initial order from the Customer and pre-configured in the ATM switch, but set to a disabled mode. Customer must initiate VCC activation with Company and necessary third party vendors.

Alternate Routing VCC
Alternate Routing VCCs provide a logical connection to an alternate host location processor/server in the event of an outage at the primary location. Alternate Routing VCCs are to be utilized in the event of an outage at the primary location only, not day-to-day use. Alternate Routing VCCs are provisioned based upon an initial order from the Customer and available at all times. The remote Customer location is provisioned with two active VCCs, one end to the primary Customer location and one end to the backup Customer location.

Multicasting VCC
Multicasting VCCs are used to communicate uni-directionally from one location to many locations. It allows Customer Equipment to send cells into the Company ATM network over a specially designated Multicast VCC. The cells are replicated and sent across various VCCs defined on the same port as the Multicast VCC. Multicast VCCs are used in conjunction with the VBR-nrt Quality of Service and SIR traffic parameter. Multicasting VCCs are not available in all regions. See table in Section 4.7.8.D for Multicasting VCC availability.

ATM Host-Link
ATM Host-Link gives the Customer the option to purchase multiple VPCs from the Company's ATM network to provide ATM connectivity for Digital Subscriber Line (DSL) Transport Services, including Wholesale DSL Transport Service and Remote LAN DSL Transport Service. Customer must obtain access to Company's ATM network by purchasing UNI Port and Access/Port Only or B-ICI Port and Access/Port Only. ATM Host-Link is offered only for DSL Transport connectivity and is applicable for all interfaces. ATM Host-Link will contain up to 10 VPCs for DS1, 25 VPCs for IMA, 100 VPCs for DS3 and 200 VPCs for OC-3. If required, additional ATM Host-Link VPCs (exceeding the quantities designated above) may be purchased individually as indicated in ASI FCC1 tariff.

ATM is provided by SBC Advanced Solutions, Inc. (SBC-ASI).
All the service terms, conditions and pricing are defined in the SBC ASI Rates, Terms and Conditions for Data Services.

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