User's Manual

Technical Notes – QoS Features on BES50

Configure BES50 Traffic Prioritization

1. Default Port Priority

A default port priority can be specified for each port on the BES50. All untagged packets entering the BES50 are

tagged with the specified default port priority, and then sorted into the appropriate priority queue at the output

port.

The default priority applies for an untagged frame received on a port set to accept all frame types (i.e, can

receive both untagged and tagged frames). The default port priority does not apply to IEEE 802.1Q VLAN

tagged frames. If the incoming frame is an IEEE 802.1Q VLAN tagged frame, the IEEE 802.1p User Priority bits

contained in the Ethernet frame will be used for traffic prioritization. If the egress port is an untagged member of

the associated VLAN, the egress frames are stripped of all VLAN tags prior to transmission.

To review and/or modify the default port priority settings, navigate to the Applications > Priority > Default Port

Priority panel.

Figure 8: BES50 Default Port Priority Settings

2. 802.1p User Priority

BES50 can use the IEEE 802.1p user priority embedded in the incoming tagged Ethernet frames to determine

the appropriate user traffic priority. Up to 8 traffic priorities are defined in IEEE 802.1D. BES50 provides a

default user priority to traffic class mapping in accordance with Annex G of the IEEE 802.1D (keep in mind there

are 4 traffic classes for BES50FE and 8 traffic classes for BES50GE).

This mapping is also user configurable if the user desired to use a different mapping. To review and/or configure

the traffic priority to traffic class mapping, navigate to the Applications > Priority > Traffic Classes panel (see

Figure 1: BES50FE Priority to Traffic Class and Figure 2: BES50GE ).