Traffic Management

Traffic Management Capabilities

6.1.3Queue Buffers

ATM SmartSwitches perform buffering using a shared-memory architecture. Buffer space is divided into queues for each class of service. In turn, ports are allocated a portion of each of the service class queues. This allocation is controlled on a per-port basis by the porttrafficcongestion commands.

Quality of service is defined on an end-to-end basis in terms of cell loss ratio, cell transfer delay, and cell delay variation.

For example, enter the show porttrafficcongestion command to view current buffer utilization.

SmartSwitch # show porttrafficcongestion

 

PortNumber(ALL)

:

PortID QueueId ServiceClass MinIndex MinValue MaxIndex MaxValue

==============================================================================

CPU

1

CBR

10

64

15

1024

CPU

2

RTVBR

8

256

13

4096

CPU

3

NRTVBR

8

256

13

4096

CPU

4

ABR

8

256

12

8192

CPU

5

UBR

8

256

12

8192

PortID

QueueId ServiceClass MinIndex MinValue MaxIndex MaxValue

==============================================================================

7A1

1

CBR

10

64

15

1024

7A1

2

RTVBR

8

256

13

4096

7A1

3

NRTVBR

8

256

13

4096

7A1

4

ABR

8

256

12

8192

7A1

5

UBR

8

256

12

8192

PortID

QueueId ServiceClass MinIndex MinValue MaxIndex MaxValue

==============================================================================

7A2

1

CBR

10

64

15

1024

7A2

2

RTVBR

8

256

13

4096

7A2

3

NRTVBR

8

256

13

4096

7A2

4

ABR

8

256

12

8192

7A2

5

UBR

8

256

12

8192

PortID

QueueId ServiceClass MinIndex MinValue MaxIndex MaxValue

==============================================================================

7A3

1

CBR

10

64

15

1024

7A3

2

RTVBR

8

256

13

4096

7A3

3

NRTVBR

8

256

13

4096

7A3

4

ABR

8

256

12

8192

7A3

5

UBR

8

256

12

8192

More(<space>/q)?:

MinValue and MaxValue are thresholds set on a per-queue, per-port basis and are measured in cells (53 bytes). The MinValue threshold is the amount of buffer space guaranteed to a call of a particular service class on the corresponding port. The MaxValue threshold is the maximum amount of buffer space that a call of a particular service class is allowed on the corresponding port.

QoS corresponds to the queues as follows:

Queue 1 — Constant Bit Rate (CBR)

Queue 2 — Real Time Variable Bit Rate (rt-VBR)

Queue 3 — Non-real time Variable Bit Rate (Nrt-VBR)

SmartSwitch ATM User Guide 6-5

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Cabletron Systems 04-0053-01 manual Queue Buffers, Cpu Ubr