Phoenix Rising BBS/phoenixrising.zip/phoenixrising/pac_bell/atm.txt

Text File | 1995-03-20 | 13KB | 356 lines

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
                [phone]

For additional information; concerning the Pacific Bell
ATM/CRS, please contact:

                Pacific Bell Product Manager
                2600 Camino Ramon, Room 3S451,
                San Ramon, CA. 94583
                [phone]