•
Layer 2 Class of Service (CoS) value—This is the 802.1p priority value in the Ethernet frame. It can be a value from 0 through 7.
The 802.1p priority is also called the
Class of Service
.
•
Layer 3 Differentiated Services Code Point (DSCP)—This is the value in the six most significant bits of the IP packet header 8-bit
DSCP field. It can be a value from 0 through 63. These values are described in RFCs 2472 and 2475. The DSCP value is
sometimes called the
DiffServ value
. The device automatically maps the DSCP value of a packet to a hardware forwarding queue.
•
ACL keyword—An ACL can also prioritize traffic and mark it before sending it along to the next hop. This is described under "QoS
options for IP ACLs" section in the
Ruckus FastIron Security Configuration Guide
.
Given the variety of different criteria, there are many possibilities for traffic classification within a stream of network traffic. For this reason, the
priority of packets must be resolved based on which criteria takes precedence. Precedence follows the schemes illustrated in the
Determining the trust level of a packet for ICX devices
figure.
Packet trust level
The following figure illustrates how ICX series devices determine the trust level of a packet. As shown in the flowchart, the first criteria
considered is whether the packet matches on an ACL that defines a priority. If this is not the case and the MAC address of the packet
matches a static entry, the packet is classified with the priority of the static MAC entry. If neither of these is true, the packet is next classified
with the ingress port default priority, then DSCP/ToS value, then 802.1p CoS value, and finally the default priority of zero (0).
NOTE
ICX 7150 devices determine internal priority differently. In ICX 7150 devices, ACL matches are first considered, and DSCP/ToS
priority is considered next, followed by the priority of the static MAC entry, then default ingress port priority, 802.1p CoS value,
and finally the default priority of zero (0).
Quality of Service
Quality of Service overview
Ruckus FastIron QoS and Traffic Management Configuration Guide, 08.0.70
12
Part Number: 53-1005294-01
