transmit-rate
QFX5100, EX4600, QFX3500, and QFX3600, Switches, QFabric Systems
transmit-rate (rate | percent percentage);
QFX10000 Switches
transmit-rate (rate | percent percentage) <exact>;
Hierarchy Level
[edit class-of-service schedulers scheduler-name]
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.
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.
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.
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.
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:
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 |
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:
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.
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.
Release Information
Statement introduced in Junos OS Release 11.1.
Exact option introduced in Junos OS Release 15.1X53-D10 for the QFX Series.