Egress Queues Setup - RACOM RAy3 User Manual

5.5.2.4. Egress queues setup

The Egress queue page allows to set parameters for four output (egress) queues available in internal
Ethernet switch of RAy unit.
Each queue is used to store frames with given priority (as set in 802.1p and DSCP configuration). The
queue depth is controlled dynamically to reach maximum utilization of the switch memory. The queue
frame egress is controlled by scheduling algorithms as described further below.
Fig. 5.25: Menu Switch settings / Interface / Egress queue
• Port name
Identification of the internal switch port. The switch ports are connected to an external port or to an
internal device (radio modem, management CPU).
○ Eth1 (port1) — The external port (with RJ45 interface) labeled "ETH1+POE".
○ Eth2 (port10) — The external port (with SFP interface) labeled "ETH2".
○ CPU (port0) — The internal port to management CPU.
○ Air (port9) — The internal port to radio modem, i.e. link to the peer unit.
• Scheduling mode
Port's Scheduling mode.
The device supports strict priority, weighted round robin, or a mixture on a per egress port selection
basis.
In the strict priority scheme all top priority frames egress for a port until that priority's queue is empty,
then the next lower priority queue's frames egress, etc. This approach can cause the lower priorities
to be starved out preventing them from transmitting any frames but also ensures that all high priority
frames egress the switch as soon as possible.
In the weighted scheme an 8, 4, 2, 1 weighting is applied to the four priorities unless an alternate
weighting is programmed into the QoS Weights Table. This approach prevents the lower priority
frames from being starved out with only a slight delay to the higher priority frames.
Some applications may require the top priority queue, or the top two priority queues to be in a fixed
priority mode while the lower queues work in the weighted approach. All scheduling modes are se-
lectable on a per port basis.
The port scheduling mode can be one of the following values:
○ weighted RRB — Use a weighted round robin queuing scheme.
○ strict pri 3 — Use Strict for priority 3 and use weighted round robin for priorities 2,1 and 0.
○ strict pri 3, 2 — Use Strict for priorities 3 and 2 and use weighted round robin for priorities 1 and
0.
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