3Com CoreBuilder 7000, Operation Manual, Page: 122 / 264

122 C
HAPTER
5: E
STABLISHING
ATM C
HANNELS
Message Conversion
Between Signaling
Protocols
In order to transmit a signaling message across interfaces which have
different signaling protocols at each end, the CoreBuilder 7000 switch
performs message conversion. The conversion handles the follow
signaling protocols:
UNI 3.0 <-> UNI 3.1
UNI 3.*<-> UNI 4.0
PNNI <-> UNI
Conversion is performed for:
message level
information element level
Quality of Service
Parameters
There are many QoS parameters that can be set for any connection.
These parameters include:
Available Bit Rate Service Class Category
Constant Bit Rate Service Class
Real-Time Variable Bit Rate Service Class
Non-Real-Time Variable Bit Rate Service Class
Unspecified Bit Rate Service Class
Available Bit Rate
Service Class
Category
ABR is an ATM layer service category for which the limiting ATM layer
transfer characteristics provided by the network may change after the
connection is established. A flow control mechanism is specified which
supports several types of feedback to control the source rate in response
to changing ATM layer transfer characteristics. This feedback is conveyed
to the source through specific control cells called Resource Management
Cells, or RM-cells. It is expected that an end-system that adapts its traffic
in accordance with the feedback will experience a low cell loss ratio and
obtain a fair share of the available bandwidth according to a network
specific allocation policy. The ABR service does not require bounding the
delay or the delay variation experienced by a given connection. ABR
service is not intended to support real-time applications.
On the establishment of an ABR connection, the end-system specifies to
the network both a maximum required bandwidth and a minimum usable
bandwidth. These are designated as peak cell rate (PCR), and the
minimum cell rate (MCR), respectively. The MCR may be specified as zero.