4 - Sprint



3.0 Switched Data Services (C.2.3)

Government requirements for data connectivity have traditionally been met by individual private networks. Technology has evolved to the point where a common, high performance data transport utility serving the Government community is feasible. The goal of the services which comprise SDS is to realize the economic and performance benefits that derive from having a true Government Information Infrastructure. These benefits include efficient use of resources, economy of procurement, a common security infrastructure, and a common platform to support cross-agency applications such as E-Mail and electronic commerce. Each of the four services described below addresses particular needs within the data communications community.

Sprint is a leader in providing data communications services to companies and Government agencies worldwide. This leadership began over 25 years ago with packet switching services, and has steadily evolved through Frame Relay and into the Internet Protocol and Asynchronous Transfer Mode (ATM) services which lead the industry today. Sprint currently enjoys leading market shares in X.25, Frame Relay, and ATM X

Sprint delivers both legacy and leading-edge data solutions around the world.

The Government has experienced the benefits of efficient use of resources, economy of procurement, a common security infrastructure, and a common platform to support cross-agency applications such as E-Mail and electronic commerce under the FTS2000 contract with Sprint. Sprint's Switched Data services will continue to provide expanded benefits under the FTS2001 services being described in this section.

3.1 Packet Switched Service (C.2.3.1)

This service, based on the X.25 protocol, is the traditional solution to the problem of consolidating multiple networks using different protocols. It provides reliable end-to-end connectivity at moderate transmission speeds. The Government has an installed base of PSS users. The following sections provide the requirements for PSS.

Sprint’s leadership in the telecommunications industry originated with the pioneering efforts of a small company called Telenet. Telenet was founded by the same group of people that developed the packet switched network for the US Defense Department Advanced Research Projects Agency (ARPA) in 1969. This network, named ARPANET, was the basis for the world’s first public packet data network, Telenet’s X.25 public data network in 1972. Telenet also pursued standardization of packet switched technology by initiating standards development with the CCITT for X.25. Today, Telenet is named Sprint and provides the

world’s largest Packet Switched Service (PSS) based on Telenet’s original X.25 network. Sprint's FTS2001 X.25 will continue to provide the Government with an extremely cost effective, reliable, and flexible method of connecting geographically dispersed locations.

Overall Network Architecture(L.38.1.1(a))

The overall network architecture, including the types and capacity of the transmission and switching media, the transmission facility(ies) configuration, and the type of equipment used in its network.

Sprint’s X.25 network is designed with redundant links between switches and redundant hardware and software at each switch location for reliability and survivability. In addition, Sprint employs a unique hierarchical architecture that segregates the access and transport functions provides scalability and enhances the network’s reliability and performance.

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XXXXRationale for Network Architecture and Design (L.38.1.1 (b))

The rationale for the network architecture design.

The hierarchical design of Sprint’s packet switched network modularizes the large network into component elements of functionality. The key functional elements of Sprint’s network, as discussed earlier, are access and transport. Data networks achieve several advantages with hierarchical architectures due to their delay tolerance. Unlike voice networks, data networks can withstand a higher degree of delay and therefore can benefit

from a hierarchical approach in their design. There are several advantages to Sprint’s hierarchical network architecture including the following:

• Scalability

• Manageability

• Performance optimization.

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Congestion and Flow Control (L.38.1.1 (c))

Congestion and flow control strategy including redundant switch and transmission facilities, control mechanisms, and the degree of flexibility inherent in the architectural design to handle predicted and unpredicted increased traffic loads and/or switch and transmission failures.

Redundant Switch and Transmission Facilities

Sprint’s network architecture, utilizing switches with hardware redundancy, redundant paths between destinations and the routing algorithm employed, provides optional paths for routing around congested networks nodes.

Control Mechanisms

Sprint’s PSS network is based on the ITU-TSS X.25 protocol standard. This protocol is extremely robust in nature with extensive error handling and error correction performed at every node within an X.25 network. Adhering to industry standards, this error handling and correction scheme is applied at each node within Sprint’s X.25 network.

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The X.25 protocol packets contain a send sequence number, P(S), and a receive sequence number, P(R) which provide the sliding window flow and congestion control. P(S) is assigned by the originating Data Terminal Equipment (DTE) on outgoing packets per Virtual Circuit (VC) and is set as one more than the preceding packets send sequence number, modulo 8 or modulo 128. P(R) contains the number of the next expected packet from the other side. Flexibility for Unexpected Traffic

Because all access switches have multiple paths to reach the next transport switches, there is inherent flexibility in the architecture to support abnormal traffic patterns. Furthermore, excess capacity is engineered into the network to allow reasonable performance to be maintained even during failure conditions. Capacity utilization is monitored to ensure that switching and transmission facilities do not exceed XXXXX under normal operating conditions. With this cushion there is sufficient capacity to redirect traffic around failed components.Sprint Equipment at Government Locations (L.38.1.1(d))

Sprint’s PSS may require the following equipment at the Government’s Service Delivery Point (SDP):

• X.25 Packet Assembler/Disassembler (PAD)

• Power Conversion Equipment

• Channel Bank

• Channel Service Unit/Data Service Unit (CSU/DSU).

X.25 Packet Assembler/Disassembler (PAD)

The X.25 Packet Assembler/Disassembler (PAD) provides the interface between the non-packet mode Data Terminal Equipment (DTE) and the X.25 network. The PAD performs the X.25 call setup, encapsulates non-X.25 protocols into the X.25 protocol packet format, and establishes the communication between the network and the user, as defined the ITU-TSS Recommendations X.3, X.28, and X.29. A typical X.25 PAD needs the environmental requirements detailed in Table 1.B.3-1

Table 1.B.3-1 X.25 PAD Environmental and Space Requirements

|Mount: |Rack Mountable |

|Equipment size: |1.75” x 17.5” x 10.56” nominal |

|Power: |-48 Volts dc nominal |

|Temperature: |40 to 85 degrees celsius |

|Humidity: |95 percent (non-condensing) |

Power Conversion Equipment

Power distribution may be required in instances where there are large amounts of specialized equipment located at Government locations. Power, in the simplest form, will require a standard 110-120 VAC/15A grounded plug into a wall receptacle The floor space and power requirements for these power conversion units detailed in Table 1.B.3-2.

Table 1.B.3-2 Floor Space and Power Requirements

|Mount: |Rack-mounted |

|Equipment size: | 22-1/2” x 16” nominal |

|Power: |109-125 Volts AC |

|Temperature: |0 to 50 degrees Celsius |

|Humidity: |95 percent (non-condensing) |

Channel Bank (CB)

Channel Banks are employed to provide DS1 circuit termination at a Government location requiring mostly voice service and minimal data services. Sprint provides integrated voice and data service via a single channelized T1 with ESF, as specified by the Bellcore Pub: SR-TSV-002275 and the ANSI T1.102/107/403 standards. The typical power and environmental requirements for a typical Channel Bank are listed in Table 1.B.3-3. Channel Banks multiplex and demultiplex the DS0 sub-channels into a DS1 channelized or fractional DS1 channelized circuit to support voice and data traffic, as illustrated in Figure 1.B.3-3.

Table 1.B.3-3 Power and Environmental Requirements for Channel Bank

|Mount: |Rack-mounted or standalone |

|Equipment Size: | 22-3/8” x 15” nominal |

|Power: |-48 Volts DC nominal |

|Temperature: |0 to 50 degrees Celsius |

|Humidity: |95 percent (non-condensing) |

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Channel Service Unit/Data Service Unit (CSU/DSU)

The CSU/DSU is required for service monitoring, troubleshooting and signal conversion and to provide the proper interface for DS1 circuit termination. The CSU/DSU provided will be resident on Government sites. CSU/DSUs are required for data services at fractional DS1,

64/56 kbps, 19.2 kbps, 9.6 kbps, and 4.8 kbps data rates. The typical power and environmental requirements for a typical CSU/DSU are listed in Table 1.B.3-4.

Table 1.B.3-4 Power and Environmental Requirements for CSU/DSU

|Mount: |standalone |

|Equipment size: |3.125” X 12” X 8.5” nominal |

|Power: |115 Volts AC |

|Temperature: |0 to 45 degrees Celsius |

|Humidity: |95 percent (non-condensing) |

Traffic Calculations (L.38.1.1 (e))

Traffic calculations that indicate network and service performance during estimated normal, 10 percent, 25 percent, and 50 percent above the estimated normal FTS2001 traffic loads and the means to ensure achieving the required performance as specified in this solicitation.

X Our network will function without effect on quality of performance when various percentages of loading increase are applied to projected FTS2001 average switched data service loading. The increase in traffic calculations indicate that network and service performance will not be affected at usage levels of even up to 50 percent above the estimated normal FTS2001 traffic loads. X

X

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Impact of Feature Usage on Service Performance (L.38.1.1 (f))

X

Network Control and Diagnostics (L.38.1.1 (g))

Sprint’s Public Data Service Center (PDSC) in Reston, VA, is the network management hub for all Sprint domestic packet/frame data services and applications. The PDSC contains several Network Control Centers (NCCs) and technical support groups, which configure, monitor, and maintain software and services.

The Service Management Center (SMC) serves as the primary customer contact for any Sprint service issues. When a problem involving a packet data service is reported to the

SMC, the SMC opens a trouble ticket and immediately routes it to the PDSC. PDSC technicians are responsible for fault isolation and repair.

The PDSC is committed to providing the best possible service for packet data services. Through the creative use of leading edge technology, Sprint has deployed new systems that offer benefits including a great increase in the PDSC’s metabolism—the speed at which we can launch new products and the power to absorb new technologies.

These new systems and processes allow Sprint to provide:

• Dramatic increases in our ability to pro-actively detect, manage, and, in many cases, automatically resolve problems

• Automatic testing and evaluation of every problem

• Automation of routine problem resolution

• Significant decreases in overall problem resolution time

• Enhancement of Sprint’s ability to manage trouble tickets

• Fast analysis and correlation of historical information for network capacity planning and traffic management

• Easy customization of support offerings, based upon user’s needs

• Automatic enforcement of optimized ticket management policies for the fastest possible problem resolution.

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Network Transmission and Synchronization Plans (L.38.1.1 (h))

Network synchronization, the communication timing within and between networks, plays a critical role as high-speed communication networks span the globe. Sprint is particularly well suited to handle the Government’s demand for worldwide data transmission because of our 100 percent digital, fiber-optic network in the U.S.—the ideal transmission medium for high-speed data transmission.

Digital network synchronization as implemented on the Sprint network, assures that the network can transport data end-to-end and interconnect with other networks with minimal degradation. The benefits of Sprint synchronization include transmission clarity, virtually error-free operation, and survivability using Digital Cross-connect System (DCS) devices.

Sprint uses either a LORAN (long range navigation) or a GPS (Global Positioning Satellite) Primary Reference Source at all of our nodes and switch sites to the Government

with state of the art plesiochronous synchronization.XAs the first U.S. carrier to provide 100 percent fiber-optic transport with plesiochronous synchronization, Sprint delivers advanced, reliable telecommunications services. The Sprint network uses a plesiochronous method of providing Stratum 1 timing sources at different network nodes rather than one centralized source. The plesiochronous technique does not experience timing degradation of long timing distribution links. This synchronization method is uniquely suitable to a total fiber-optic network because of the automatic reconfiguration capability provided by diverse fiber links from a node to different Stratum 1 clocks, which are provided via Loran-C systems.

The Loran-C system, maintained by the U.S. Coast Guard, is a low-frequency terrestrial radio navigation system. It operates from 90 to 100 kHz, with a carrier frequency of 100 kHz. Because these low frequency radio waves follow the earth’s curvature, they are both stable and unaffected by the ionosphere. Loran-C transmissions are referenced to Cesium Beam frequency standards (Stratum 1) and are Universal Time Coordinated (UTC). The benefits of the Loran-C synchronization method are assured through multiple redundant Stratum 1 primary reference sources.

The GPS system uses atomic clocks mounted inside satellites for distributing UCT (Universal Coordinated Time) timing. These satellites then transmit timing beacons that cover broad areas of the earth. Originally developed for military use, GPS has recently been made available for commercial applications. Future plans call for Sprint to migrate more and more networks to GPS in order to take advantage of its ability to synchronize geographically disparate networks.

As one of the world’s largest data network providers and with over 20 years of experience, Sprint is well positioned to provide the Government with reliable worldwide telecommunications.

Approach for Incorporating Emerging Services (L.38.1.1 (i))

Sprint is continually enhancing services and investing in the latest technologies to benefit end users and customers. X

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XXApproach for Adapting to Meet Government’s Service Requirements (L.38.1.1 (j))

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XMaintaining attentive relationships with our customers enables Sprint to pro-actively and efficiently execute our tactical and strategic business plans. Thorough understanding of the scope and range of our customers requirements allows maximum leverage of economics of scale and optimization of resources for increased margins. X

XAdditionally, Account Teams participate in and influence corporate-wide initiatives to ensure that Sprint can provide winning solutions for our customers future requirements. X

XNew products and services are introduced to customer and potential customers via pilot programs and field trials, which are linked back to business and market development groups, which shape Sprint’s strategic direction. Sprint emphasizes customer participation in leading edge focus groups both internal and external to the organization. Additionally, Sprint account teams and LCTs engage in program reviews with our customers, encouraging their input and sharing of ideas. All of these techniques are used by Sprint to listen and learn from our customers; how it falls to the account manager and LCTs to develop account specific application.

The importance and value of key products and service features to our Government customers is specifically documented in their Requests for Proposals (RFPs). LCTs monitor, compare and evaluate RFPs to identify specific demand trends.

Additionally, LCTs and account managers maintain attentive relationships. For example, we are providing our customers with training on the new Federal Telecommunications legislation, encouraging discussion on strategies to optimize the Government customers benefit from the changing market.

Sprint assesses these customer requirements and develops plans to integrate these needs with the Corporation’s strategic product and business goals. This is evidenced in Sprint’s pro-active role in driving Sprint’s ATM, Internet and Managed Network Services, all of which were direct results of Government customer requirements.

Domestic and International Service Coverage (L.38.1.1 (k))

Sprint’s PSS is accessible from over 500 locations domestically and more than 300 locations internationally. Extensive local coverage provides end users a local phone number to access the network regardless of where they are located. Multiple dial access speeds from 300 bps to 14.4 kbps are available. The asynchronous dial facilities provide advanced speeds, error correction, and data compression technologies designed into our access rotaries.

Using a terminal, PC, or host computer equipped with an asynchronous modem, a user dials the closest local access center, establishes a connection with the data network, and then sends and receives data with other devices connected to the network. For remote locations, a toll free dial-in service offers . The toll free dial-in service can also provide users with their own personalized toll-free number to access the X.25 network from XXXX. These same features are available when dialing an X.25 node from an international location, as well.X

XThe Global X.25 network offers global connections from most major world business centers. XXXXX

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International Carriers and Service Providers Performance Standards (L.38.1.1 (l))

XDiverse routing and the redundant nature of the XXXXnodal switches enables Global X.25 to achieve 99.9 percent availability in actual operational use. The design

and advanced technology of the network enables normal network updating to be undertaken in parallel with operational use, enhancing the Network’s availability performance.

Network Evolution Approach to Optimizing the Government’s Switched Data Cost Effectiveness (L.38.1.1 (m))

The Sprint Government Service Division sales and engineering teams are dedicated to developing customized solutions that exceed the Governments performance requirements and also minimize the Governments costs. Every solution will be evaluated based upon traffic pattern, traffic volume, as well as usage duration. Sprint will minimize the Governments costs by conducting engineering trade-off studies to determine how to minimize access charges. XXXXXXX.

3.1.1 Packet Switched Service Access Requirements (C.2.3.1.1)

3.1.1.1 Basic Service Description (C.2.3.1.1.1)

PSS shall provide a packet-switched, connection-oriented, data transmission service at data rates up to DS0.

PSS shall conform to the ITU-TSS X.25/X.28/X.29/X.3/X.32/X.75/X.121 and optionally X.75 recommendations, Federal Information Processing Standard-Publication (FIPSPUB) 100-1, Federal-Standard (FED-STD) 1013/1020A/1030A/1033, and ANSI T1.504/614. The contractor shall support packet lengths of 64, 128, 256, 512 and 1024 bytes, at a minimum.

Sprint's PSS will provide the Government a packet-switched, connection-oriented, data transmission service at data rates up to DSO. In addition, Sprints service is based on the ITU-TSS X.25 protocol, which allows Sprint to offer even higher data rates up to 256 Kbps.

Sprint is a strong advocate of standards development and compliance. For PSS Sprint will support the ITU-TSS X.25, X.28, X.29, X.3, X. 32, X.75, X.121 recommendations, the Federal Information Processing Standards-Publication (FIPS-PUB) 100-1 standard, Federal-Standard (FED-STD) 1013, 1020A, 1030A, 1033, and the ANSI T1.504 and T1.614 standards. Sprint will support packet lengths of 64, 128, 256, 512, and 1024 bytes.

Pursuant to Section C.2.1.16, the contractor shall provide dedicated, , and optionally internetworked originating and/or terminating access connections for PSS calls. Originating access connections shall connect PSS on-net originating locations with the associated POP. Terminating access connections shall connect the terminating POP with PSS on-net terminating locations.

Sprint will provide dedicated access and internetworked originating and/or terminating access connections for PSS calls. Originating access connections will connect PSS on-net originating locations with the associated POP. Terminating access connections will connect the terminating POP with PSS on-net terminating locations.

PSS access shall be delivered directly to the user’s terminal equipment. The user’s terminal may be either “packet-mode DTE” which supports X.25 protocol or “non-packet-mode DTE or terminal,” which does not support X.25 protocol. User equipment supported shall include, but not be limited to, multiplexing/switching devices such as PBXs, channel banks, routers, or Multiplexers; DTE (or packet-mode DTE); asynchronous ASCII terminals; IBM Binary Synchronous Communications (BSC) protocol terminals; IBM SNA/Synchronous Data Link Control (SDLC) terminals; Unisys Poll/Select terminals. The contractor shall provide Packet Assembly/Disassembly (PAD) capability. The interfaces to these equipment types are defined in Section C.2.3.1.1.4.1.

Sprint's PSS access will be delivered directly to the users terminal equipment. Sprint’s PSS will support packet-mode DTEs or non-packet mode DTEs via an X.25 Packet Assembler/Disassembler (PAD), capable interfacing between the non-packet DTE and the network. Devices such as PBXs, channel banks, routers, and multiplexers will be supported on the network. Multiprotocol environments are also supported, including asynchronous ASCII, IBM BSC, IBM SDLC, and Unisys Poll Select protocols, through the use of PAD devices, capable of encapsulating the non-X.25 protocol into an X.25 packet.

3.1.1.1.1 Additional Capabilities

The contractor may exceed the basic requirements by providing PSS access via internetworked access arrangement (see Section C.2.1.16). When this access is provided the following additional capabilities would be supported:

(a) The capability for a DTE to send and receive data by setting up Permanent Virtual Circuits (PVC) and/or Switched Virtual Circuits (SVC).

(b) The capability to support a numbering plan that would follow the ITU-TSS X.121 numbering plan.

(c) The contractor would support the following capabilities as specified in FIPS-PUB 100-1:

(1) Reverse charging

(2) Reverse charging acceptance

(3) Local charging prevention

(4) Nonstandard default packet size

(5) Nonstandard default window size

(6) Incoming calls barred

(7) Outgoing calls barred

(8) One-way logical channel outgoing

(9) One-way logical channel incoming

(10) Default throughput classes assignment

(11) Flow control parameter negotiation

(12) Throughput class negotiation

(13) Closed User Group (CUG)-related facilities, including CUG with outgoing access, CUG with incoming access, incoming calls barred within user group, outgoing calls barred within user group, bilateral CUG, bilateral CUG with outgoing access, and CUG with outgoing access selection

(14) Fast select

(15) Fast select acceptance

(16) Hunt group facilities, including round robin, closest, and ordered list

(17) Support for throughput classes of 1.2 kb/s, 2.4 kb/s, 4.8 kb/s, 9.6 kb/s, through 48 kb/s

(18) Transit delay selection and notification

(19) Abbreviated address calling

(20) Charging information

(21) Call redirection notification

(22) Called line address modification notification

(23) On-line facilities registration

(24) Extended packet sequence numbering (modulo 128)

(25) Packet retransmission

(26) Multilink procedure

(27) Direct call

(28) D-bit modification

(29) Call redirection

(30) Network User Identification (NUI)

(31) Extended frame sequence numbering

(32) Call deflection subscription

(33) Call deflection selection

Sprint will exceed the basic service requirements by providing internetworked access arrangements and by supporting the following enhanced PSS capabilities:

• Sprint’s PSS will provide the capability to send and receive data by setting up Permanent Virtual Circuits (PVCs) and Switched Virtual Circuits (SVCs) via an X.25 Packet Assembler/Disassembler (PAD) hardware or software located at the Government’s Service Delivery Point (SDP). PAD functionality can be provided by a dedicated PAD device or by software running on a Personal Computer (PC). The PAD hardware/software provides the interface between a Data Terminal Equipment (DTE) and the X.25 network as defined in the ITU-TSS Recommendations X.3, X.28, and X.29.

• Sprint developed the X.25 protocol standards in conjunction with the CCITT, now known as the ITU international standards setting organization. Within the standards are set forth the use of ITU-TSS X.121 numbering plan as the standard for network addressing. Sprint will support the X.121 numbering plan and utilizes the numbering plan internally within and to all DTE devices connected to the network.

• The X.25 network Access Switches will fully support PSS fully supports all features and capabilities, known as X.25 User Facilities, on a Virtual Circuit, as specified in FIPS-PUB 100-1. Facilities may for a Virtual Circuit are established by several methods.

– Facilities may be subscribed to on a per call basis and are established between the calling DTE and the X.25 Access Switch within the network during the X.25 call setup procedure.

– Facilities may be pre-subscribed by hard-coding the Facility at the X.25 Access Switch.

– Facilities may be negotiated between the two end DTE devices during the call setup procedure.

Sprint supports all User Facilities listed below, as specified in the FIPS-PUB 100-1.

Reverse Charging

The Reverse Charging facility allows the Calling DTE (the originating DTE) to specify an X.25 call as a collect call. However, if the Called DTE (the destination DTE) has not subscribed to the Reverse Charging Acceptance facility (described below), the call is not accepted and cleared by the network.

Reverse Charging Acceptance

The Reverse Charging Acceptance facility authorizes the network Access Switch to deliver, or accept, incoming calls which request the Reverse Charging facility. If the Called DTE does not subscribe to this facility, the network will clear any incoming calls specifying the Reverse Charging facility.

Local Charging Prevention

Sprint PSS will consider offering this service based on market demand and business conditions. The functionality of this feature is similar to that offered by not subscribing to Reverse Charge Acceptance.

Nonstandard Default Packet Size

The Nonstandard Default Packet Size facility is used to override the default packet size set by the network Access Switch. Packet size is the maximum number of octets within a data packet. The standard default packet size for the X.25 network is 128 octets. Using this facility the DTE can establish nonstandard packet sizes ranging from 16 to 4096 octets.

Nonstandard Default Window Size

The Nonstandard Default Window Size facility is used to override the default window size set by the network Access Switch. Window size is the number of outstanding packets (per call) which may be sent before an authorization to send more packets is received. The standard window size is set for two. This facility allows the DTE to specify a window size other than two, ranging from 1 to 7 or 128.

Incoming Calls Barred

The Incoming Calls Barred facility prevents any incoming calls from being delivered to the DTE. A user may wish to initiate outgoing calls only and this facility which is pre-subscribed with the network Access Switch will clear any incoming calls before it reaches the DTE.

Outgoing Calls Barred

The Outgoing Calls Barred facility is pre-subscribed and prevents the network Access Switch from allowing the DTE to place any outgoing calls and only allows the acceptance incoming calls.

One-Way Logical Channel Outgoing

The One-Way Logical Channel Outgoing facility restricts the X.25 logical channel to the originating outgoing virtual circuit call setup.

One-Way Logical Channel Incoming

The One-Way Logical Channel Incoming facility restricts the logical to receive incoming calls only.

Default Throughput Classes Assignment

The Default Throughput Classes Assignment facility allows the DTE, during the call setup procedure, to establish a throughput class that is not equal to the access line speed.

Flow Control Parameter Negotiation

The Flow Control Parameter Negotiation facility allows the DTE to request a different packet and window size for each direction of transmission. The facility permits the DTE to specify the packet and window size on a per call basis. This facility is negotiated agreed to by the two end DTE devices during the call setup procedure and is used when greater throughput must be achieved by increasing the packet and window sizes beyond the default settings.

Throughput Class Negotiation

The Throughput Class Negotiation facility is used to define the number of bits per second that can be transferred over a virtual circuit that is different from the access line speed.

Closed User Group (CUG)-Related Facilities

There are several variations of the Closed User Group (CUG) facility. A CUG is a list of DTE addresses that are grouped as a single “user group”. The various types of CUG facilities allow DTEs to establish virtual circuits to members of the CUG and deny access or to or from DTEs not included in the CUG. This facility is primarily used to restrict access to systems on the network to a selected group of addresses.

The following CUG facilities will be available on Sprint’s PSS:

• CUG with outgoing access – By specifying this variation of the CUG facility, the DTE may initiate calls to any another member of the CUG and also to any other DTE outside of the CUG. With this CUG facility disabled, the DTE is only allowed to make outgoing calls to DTEs within the user group.

• CUG with incoming access – By specifying this CUG facility, the DTE may accept calls from any DTE, including those not included with the CUG. With this CUG facility disabled, the DTE is only allowed to accept incoming calls from DTEs within the user group.

• Incoming calls barred with user group – This CUG facility allows the DTE to accept incoming calls only from DTEs within the user group.

• Outgoing calls barred with user group – This CUG facility allows the DTE to make outgoing calls only to DTEs within the user group.

• Bilateral CUG – Bilateral CUG facilities enable pairs of DTEs to form bilateral relationships allowing access between each other while excluding access to or from other DTEs with which such a relationship has not yet been formed.

– Bilateral CUG with outgoing access – The Bilateral CUG with outgoing access facility enables the DTE to one or more bilateral closed user groups and to establish virtual circuits with DTEs outside of the bilateral closed user group. With this facility disabled, the DTE cannot make calls to DTEs outside of the bilateral closed user group.

– CUG with outgoing access selection – This CUG facility allows a DTE to make outgoing calls that can be accepted by DTEs with Bilateral CUGs. This facility must be used to originate a call to a DTE with established Bilateral CUG.

Fast Select

The Fast Select facility permits up to 128 octets of user data to be appended to the CALL REQUEST, CALL ACCEPT, and CLEAR REQUEST packets used during the call setup procedure. This facility can be used to minimize transmission of multiple packets to transmit data, by appending user data to packets that generally do not carry user data. With this facility it is possible to transmit data with only three packets. This facility is often used for short duration data transfer, such as the credit card validation transactions.

Fast Select Acceptance

The Fast Select Acceptance enable a DTE to accept incoming fast select packet call requests.

Hunt Group Facilities

Hunt group facilities allows the network access switch to distribute incoming calls to more than one destination DTE within the hunt group of addresses. For example, a Hunt group may consist of three addresses to three different DTEs connected to the same network access switch. As incoming calls are received by the access switch destined for one of the three DTEs, this facility enable the access switch to distribute the call in various methods. The facility enables the access switch to distribute the calls either in a round robin fashion, send the incoming call to the geographically closest DTE, or in an ordered list.

Throughput Classes

Sprint PSS will provide support for throughput classes of 1.2 kb/s, 2.4 kb/s, 4.8 kb/s, 9.6 kb/s through 48 kb/s as specified in FIPS-PUB 100-1.

Transit Delay Selection And Notification

Transit Delay Selection and Notification facility permits the selection and indication, on a per call basis, of the transmit delay applicable to a virtual circuit. The network will allocate resources and route the virtual circuit path in a manner such that the transmit delay does not exceed the selected delay.

Abbreviated address calling

The Abbreviated Address Calling facility allows the DTE to recognize an address that has been shortened within the CALL REQUEST packet of an incoming call. The Address field within the CALL REQUEST packet is 14 bits long, however, this field can be abbreviated to 10 bits in length when this facility is used.

Charging information

Charging Information can be either pre-subscribed or established during the call setup procedure. This facility will enable the Called DTE (the destination DTE) to send information about the charge for that call.

Call redirection notification

The Call Redirection Notification facility is used redirect incoming calls to another address. This facility is used when an address change has occurred or the DTE no longer exists and all calls to that DTE must be redirected to another replacement DTE. This feature can also be used to redirect calls away from a DTE that is down or off-line to a back up DTE.

Called Line Address Modification Notification

Called Line Address Modification Notification facility is used by the X.25 access switch to notify the Calling DTE (the originating DTE) that the address of the Called DTE (the destination DTE) is being modified. This facility is used when the destination DTE has changed addresses and must accept calls from users establishing calls the old address. The notification is in the CALL CONNECTED packet or the CLEAR INDICATION packet.

On-Line Facilities Registration

The On-Line Facilities Registration enables the Calling DTE (the originating DTE) to request a list of facilities the Called DTE (the destination DTE) will support.

Extended Packet Sequence Numbering (Modulo 128)

Extended Packet Sequence Numbering allows the interface between the DTE and the network access switch to use a modulo 128 sequence numbering of packets. The default packet sequence numbering is modulo 8.

Packet Retransmission

The Packet Retransmission facility enables the network access switch to retransmit the last data packet transmitted when it receives a DTE REJECT packet from a receiving DTE.

Multilink Procedure

Multilink Procedure allows the network switch to simultaneous support multiple connections through a intermediate layer functioning between the Packet Layer (Layer three on the OSI model) and the Link Layer (Layer two on the OSI model). Multilink establishes a second virtual Link Layer session to support two different Link Layer sessions simultaneously.

Direct Call

The Direct Call facility is pre-subscribed and allows the DTE to always place an outgoing call to a pre-specified DTE address.

D-Bit Modification

The D-Bit Modification facility enables the DTE to change the state of the D-bit field within a data packet.

Call Redirection

The Call Redirection facility will redirect an incoming call to an alternate DTE if the destination DTE is out of order or busy.

The originating end user must procure PSS services with a provider that has a PSS internetworked access arrangement with Sprint. Sprint will support the above features provided the access provider has implemented them in accordance with FIPS-PUB 100-1. In addition, the user at the terminating end must subscribe to Sprint's PSS service and features that are compatible with the internetworked access location.

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