Configuration Guide User guide

FastIron Configuration Guide 1971
53-1002494-02
QoS queues
QoS behavior for trusting Layer 2 (802.1p) in an IronStack
By default, Layer 2 trust is enabled. Because priority 7 is reserved for stacking control packets, any
ingress data traffic with priority 7 is mapped to internal hardware queue 6. All other priorities are
mapped to their corresponding queues.
QoS behavior for trusting Layer 3 (DSCP) in an IronStack
When the trust dscp mode is enabled, packets arriving with DSCP values 56 to 63 are mapped to
internal hardware queue 6. All other DSCP values are mapped to their corresponding internal
hardware queues.
QoS behavior on port priority and VLAN priority
in an IronStack
Port priority has a higher precedence than the 802.1p priority examination. If port priority is set to
7, all incoming traffic is mapped to internal hardware queue 6.
When stacking is not enabled on a device, all priorities are mapped to their corresponding queues
without restrictions.
QoS behavior for 802.1p marking in an IronStack
By default when stacking mode is enabled, 802.1p marking is enabled. Outgoing tagged traffic is
marked with 802.1p in the VLAN tag based on the internal hardware queue into which ingress
traffic was classified. As an exception, QoS priority 7 mapped to priority 6 will have the marking for
hardware queue 7.
When stacking mode is disabled, outgoing traffic is not marked with 802.1p based on the internal
hardware queue.
QoS queues
Brocade devices support the eight QoS queues (qosp0 through qosp7) listed in Table 333.
TABLE 333 QoS queues
QoS priority level QoS queue
0 qosp0 (lowest priority queue)
1qosp1
2qosp2
3qosp3
4qosp4
5qosp5
6qosp6
7 qosp7 (highest priority queue)