Brocade Network OS Administrator’s Guide v4.1.1 - Manual (Page 482)

• DSCP trust is disabled in VCS mode as it is for CoS trust.
• There are no default DSCP maps in VCS mode. Default maps occur when DSCP trust is enabled in
standalone mode.
• A nondefault DSCP-Traffic-Class map has the following restrictions:
‐ A DSCP value cannot be classified to Traffic Class 7.
‐ A DSCP value cannot be classified to a queue that carries lossless traffic (by default
Traffic Class 3).
• A nondefault DSCP-CoS map has the following restrictions:
‐ A DSCP value cannot be marked to CoS 7.
‐ A DSCP value cannot be marked to lossless priority (by default CoS 3).
• Lossless priorities are identified through the CEE map.
• To enable DSCP based marking or classification, a nondefault DSCP-Traffic-Class map and a
DSCP-CoS map have to be applied on the interface.
• To apply a DSCP-Traffic-Class or DSCP-CoS map to an interface, the CoS and Traffic Class values
have to be remarked for lossless priorities. For example, when DSCP-Traffic-Class map "abcd" is
created, it will have the default contents. When this map is applied to an interface, an error will
display that the fabric and lossless priorities are used in the map and it cannot be applied on the
interface.
• When a valid DSCP-Traffic-Class map and DSCP-CoS map are applied on the interface, then
DSCP trust is enabled with the configured maps.
Port-based Policer
The port-based Policer feature controls the amount of bandwidth consumed by an individual flow or
aggregate of flows by limiting the inbound and outbound traffic rate on an individual port according to
criteria defined by the user. The Policer provides rate control by prioritizing or dropping ingress and
egress packets classified according to a two-rate, three-color marking scheme defined by RFC 4115.
This feature is supported only on Brocade VDX 8770-4, VDX 8770-8, and later models.
Port-based Policer features
The Policer supports the following features.
• A color-based priority mapping scheme for limiting traffic rates.
‐ One-rate, two-color policing with "conform" color options. "Violate" color traffic will be
dropped.
‐ Two-rate, three-color policing with "conform" and "exceed" color options. "Violate" color
traffic will be dropped.
• A policing option that allows packet headers to be modified for IP precedence.
• Policing options that allow packet headers to be modified for Class of Service (CoS).
• Policing options that allow packet headers to be modified for Differentiated Services Code Point
(DSCP).
• Policing options that allow packets to be assigned to a traffic class (0-7).
Color-based priority
The following is the color-based priority mapping scheme for limiting traffic rate:
Port-based Policer
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