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JUNOSe 11.1.x Quality of Service Configuration Guide
Improper configuration of the two schedulers might create an inefficient scenario in
which extra latency is introduced, or might cause the scheduler to underuse the link.
To configure integration of the schedulers, use the qos-mode-port commands listed
in Table 16 on page 162.
Table 16: qos-mode-port Commands
NOTE: For ERX7xx models, ERX14xx models, and the ERX310 router, the
qos-mode-port commands are valid only for the major interface on port 0.
To properly integrate the schedulers, make sure that the HRR and the SAR schedulers
shape packets at the same rate. If the HRR scheduler sends packets at a higher rate
than the SAR scheduler shapes them, the SAR scheduler can become congested and
block the entire port.
To manage the integration of the HRR and the SAR schedulers:
1.
2.
3.
162
Integrating the HRR Scheduler and SAR Scheduler
Default integrated QoS port mode ATM application controls the scheduling
facilities of the SAR scheduler.
Low-latency QoS port mode HRR scheduler controls the traffic rate.
Low-CDV QoS port mode HRR scheduler and the SAR scheduler work together
to schedule traffic.
Command
no qos-mode-port (default integrated mode)
qos-mode-port low-cdv
qos-mode-port low-latency
qos-mode-port
Specify the cell-based shaping mode.
See "Configuring the QoS Shaping Mode for ATM Interfaces" on page 174.
Configure low-CDV QoS port mode to ensure that the HRR and SAR schedulers
are configured at the same rate.
See "Configuring Low-CDV Mode for Per-Port Queuing on ATM Interfaces" on
page 171.
Configure the QoS application to control the SAR scheduler's operation. In this
mode you configure both schedulers using scheduler profiles and QoS profiles.
The E Series router then ensures that VPs and VCs are shaped to the same rates
in both schedulers.
Backpressure
SAR Buffering
VC and port
significant
port
normal
port
minimal
port
minimal
Scheduling
SAR
SAR and HRR
HRR
HRR
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Troubleshooting
