Specifications

102 Implementing IBM System Networking 10Gb Ethernet Switches
򐂰 Re-mark the 802.1p field.
򐂰 Set the COS queue.
2.9.4 ACL metering and re-marking
You can define a profile for the aggregate traffic that flows through the switch by configuring a
QoS meter (if wanted) and assigning ACLs to ports. Actions taken by an ACL are called
In-Profile actions. You can configure additional In-Profile and Out-of-Profile actions on a port.
Data traffic can be metered, and re-marked to ensure that the traffic flow provides certain
levels of service in terms of bandwidth for different types of network traffic.
Metering
QoS metering provides different levels of service to data streams through user-configurable
parameters. A meter is used to measure the traffic stream against a traffic profile that
you create.
Thus, creating meters yields In-Profile and Out-of-Profile traffic for each ACL, as follows:
򐂰 In-Profile: If there is no meter configured or if the packet conforms to the meter, the packet
is classified as In-Profile.
򐂰 Out-of-Profile: If a meter is configured and the packet does not conform to the meter
(exceeds the committed rate or maximum burst rate of the meter), the packet is classified
as Out-of-Profile.
Using meters, you set a Committed Rate in Kbps (in multiples of 64). All traffic within this
Committed Rate is In-Profile. Additionally, you can set a Maximum Burst Size that specifies
an allowed data burst larger than the Committed Rate for a brief period. These parameters
define the In-Profile traffic.
Meters keep the sorted packets within certain parameters. You can configure a meter on an
ACL, and perform actions on metered traffic, such as packet re-marking.
Re-Marking
Re-marking allows the treatment of packets to be reset based on new network specifications
or wanted levels of service. You can configure the ACL to re-mark a packet as follows:
򐂰 Change the DSCP value of a packet, which is used to specify the service level that traffic
should receive.
򐂰 Change the 802.1p priority of a packet.
2.9.5 DiffServ Code Points
The six most significant bits in the TOS byte of the IP header are defined as DiffServ Code
Points (DSCP). Packets are marked with a certain value that depends on the type of
treatment the packet must receive in the network device. DSCP is a measure of the QoS level
of the packet.
Metering: Metering is not supported for IPv6 ACLs. All traffic that matches an IPv6 ACL
is considered in-profile for re-marking purposes.