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transmit-rate

 

List of Syntax

QFX5100, EX4600, QFX3500, and QFX3600, Switches, QFabric Systems

QFX10000 Switches

QFX5100, EX4600, QFX3500, and QFX3600, Switches, QFabric Systems

QFX10000 Switches

Hierarchy Level

Release Information

Statement introduced in Junos OS Release 11.1 for the QFX Series.

Statement introduced in Junos OS Release 14.1X53-D20 for the OCX Series.

Exact option introduced in Junos OS Release 15.1X53-D10 for the QFX Series.

Description

On QFX5100, EX4600, QFX3500, and QFX3600 switches, and on QFabric systems, the transmit rate specifies the minimum guaranteed transmission rate or percentage for a queue (forwarding class) scheduler. The queue transmit rate also determines the amount of excess (extra) priority group bandwidth that the queue can share on switches that support enhanced transmission selection (ETS) hierarchical scheduling.

On QFX10000 switches, the transmit rate specifies the minimum guaranteed transmission rate or percentage for a queue (forwarding class) scheduler. The queue transmit rate also determines the amount of excess (extra) port bandwidth the queue can share if you do not explicitly configure an excess rate in the scheduler. The transmit rate also determines the amount of excess (extra) priority group bandwidth that the queue can share on switches that support enhanced transmission selection (ETS) hierarchical scheduling.

On QFX10000 switch strict-high priority queues, the transmit rate limits the amount of traffic the switch treats as strict-high priority traffic. Traffic up to the transmit rate receives strict-high priority treatment. The switch treats traffic that exceeds the transmit rate as best-effort traffic that receives an excess bandwidth sharing weight of “1”; you cannot configure an excess rate on a strict-high priority queue, and unlike queues with other scheduling priorities, the switch does not use the transmit rate to determine extra bandwidth sharing for strict-high priority queues.

Caution

We strongly recommend that you configure a transmit rate on strict-high priority queues to limit the amount of traffic the switch treats as strict-high priority traffic on those queues. This is especially important if you configure more than one strict-high priority queue on a port. To prevent a strict-high priority queue from starving the other queues on a port, we recommend that you always configure a transmit rate, even if you only configure one strict-high priority queue.

Note

For ETS, the transmit-rate setting works only if you also configure the guaranteed-rate in the traffic control profile that is attached to the forwarding class set to which the queue belongs. If you do not configure the guaranteed rate, the minimum guaranteed rate for individual queues that you set using the transmit-rate statement does not work. The sum of all queue transmit rates in a forwarding class set should not exceed the traffic control profile guaranteed rate.

Note

On QFX5100, EX4600, QFX3500, and QFX3600 switches, and on QFabric systems, you cannot configure a transmit rate for a strict-high priority queue. Queues (forwarding classes) with a configured transmit rate cannot be included in a forwarding class set that has a strict-high priority queue. To prevent strict-high priority queues from consuming all of the available bandwidth on these switches, we recommend that you configure a shaping rate to set a maximum amount of bandwidth for strict-high priority queues.

Note

For transmit rates below 1 Gbps, we recommend that you configure the transmit rate as a percentage instead of as a fixed rate. This is because the system converts fixed rates into percentages and may round small fixed rates to a lower percentage. For example, a fixed rate of 350 Mbps is rounded down to 3 percent instead of 3.5 percent.

Default

On QFX5100, EX4600, QFX3500, and QFX3600 switches, and on QFabric systems, if you do not configure the transmit rate, the default scheduler transmission rate and buffer size percentages for queues 0 through 11 are:

Table 1: Default Transmit Rates for QFX5100, EX4600, QFX3500, and QFX3600 Switches, and QFabric Systems

Queue Number

Default Minimum Guaranteed Bandwidth (Transmit Rate)

0 (best-effort)

5 %

1

0

2

0

3 (fcoe)

35 %

4 (no-loss)

35 %

5

0

6

0

7 (network control)

5 %

8 (mcast)

20 %

9

0

10

0

11

0

Note

OCX Series switches do not support lossless transport. The OCX Series default DSCP classifier does not classify traffic into the default lossless fcoe and no-loss forwarding classes. The bandwidth that the default scheduler allocates to the default fcoe and no-loss forwarding classes on other switches is allocated to the default best-effort, network-control, and mcast forwarding classes on OCX Series switches.

On QFX10000 switches, if you do not configure the transmit rate, the default scheduler transmission rate and buffer size percentages for queues 0 through 7 are:

Table 2: Default Transmit Rates for QFX10000 Switches

Queue Number

Default Minimum Guaranteed Bandwidth (Transmit Rate)

0 (best-effort)

15 %

1

0

2

0

3 (fcoe)

35 %

4 (no-loss)

35 %

5

0

6

0

7 (network control)

15 %

Configure schedulers if you want to change the minimum guaranteed bandwidth and other queue characteristics.

Options

rate—Minimum transmission rate for the queue, in bps. You can specify a value in bits-per-second either as a complete decimal number or as a decimal number followed by the abbreviation k (1000), m (1,000,000), or g (1,000,000,000).

Range: 1000 through 10,000,000,000 bps on 10-Gigabit interfaces, 1000 through 40,000,000,000 bps on 40-Gigabit interfaces.

percent percentage—Minimum percentage of transmission capacity allocated to the queue.

Range: 1 through 100 percent

exact—(QFX10000 switches only) Shape queues that are not strict-high priority queues to the transmit rate so that the transmit rate is the maximum bandwidth limit. Traffic that exceeds the exact transmit rate is dropped. You cannot set an excess rate on queues configured as transmit-rate (rate | percentage) exact because the purpose of setting an exact transmit rate is to set a maximum bandwidth (shaping rate) on the traffic.

Note

On QFX10000 switches, oversubscribing all 8 queues configured with the transmit rate exact (shaping) statement at the [edit class-of-service schedulers scheduler-name] hierarchy level might result in less than 100 percent utilization of port bandwidth.

Required Privilege Level

interfaces—To view this statement in the configuration.

interface-control—To add this statement to the configuration.