User Manual

24-Port and 48-Port Gigabit Ethernet PoE+ Smart Switches with 4 SFP Ports
Configuration Examples User Manual523
Traffic conditioning policy
Traffic conditioning pertains to actions performed on incoming traffic. Several distinct QoS
actions are associated with traffic conditioning:
• Dropping. Drop a packet upon arrival. This is useful for emulating access control list
operation using DiffServ, especially when DiffServ and ACL cannot coexist on the same
interface.
• Marking IP DSCP or IP Precedence. Marking/re-marking the Dif
fServ code point in a
packet with the DSCP value representing the service level associated with a particular
DiffServ traffic class. Alternatively, the IP precedence value of the packet can be
marked/re-marked.
• Marking CoS (802.1p). Sets the 3-bit priority field in the first/only 802.1p header to a
specified value when packets are transmitted for the traf
fic class. An 802.1p header is
inserted if it does not already exist. This is useful for assigning a Layer 2 priority level
based on a DiffServ forwarding class (such as the DSCP or IP precedence value)
definition to convey some QoS characteristics to downstream switches that do not
routinely look at the DSCP value in the IP header.
• Policing.
A method of constraining incoming traffic associated with a particular class so
that it conforms to the terms of the TCS. Packets that do not conform to the policy are
always dropped (no other actions are available for such packets). The DiffServ feature
supports the following types of traffic policing treatments (actions) for packets that
confirm to the policy:
• drop.
The packet is dropped.
• mark cos.
The 802.1p user priority bits are (re)marked and forwarded.
• mark dscp.
The packet DSCP is (re)marked and forwarded.
• mark prec.
The packet IP Precedence is (re)marked and forwarded.
• send.
The packet is forwarded without DiffServ modification.
• Counting. Updating octet and packet statistics to keep track of data handling along traf
fic
paths within DiffServ. In this DiffServ feature, counters are not explicitly configured by the
user, but are designed into the system based on the DiffServ policy being created. For
more information, see
Monitor the switch and the ports on page 452.
• Assigning QoS Queue. Directs a traf
fic stream to the specified QoS queue. This allows a
traffic classifier to specify which one of the supported hardware queues are used for
handling packets belonging to the class.
• Redirecting. Forces a classified traf
fic stream to a specified egress port (physical or
LAG). This can occur in addition to any marking or policing action. It can also be specified
along with a QoS queue assignment.