LevelOne GTL-2691 - Manual (Page 281)

C HAPTER 10 | Class of Service
Layer 3/4 Priority Settings
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Figure 126: Mapping CoS Values to Egress Queues
L AYER 3/4 P RIORITY S ETTINGS
Mapping Layer 3/4 Priorities to CoS Values
The switch supports several common methods of prioritizing layer 3/4
traffic to meet application requirements. Traffic priorities can be specified in
the IP header of a frame, using the priority bits in the Type of Service (ToS)
octet, or the number of the TCP/UDP port. If priority bits are used, the ToS
octet may contain three bits for IP Precedence or six bits for Differentiated
Services Code Point (DSCP) service. When these services are enabled, the
priorities are mapped to a Class of Service value by the switch, and the
traffic then sent to the corresponding output queue.
Because different priority information may be contained in the traffic, this
switch maps priority values to the output queues in the following manner:
◆ The precedence for priority mapping is IP Port Priority, IP Precedence or
DSCP Priority, and then Default Port Priority.
◆ IP Precedence and IP DSCP cannot both be enabled. Enabling one of
these priority types will automatically disable the other type.
M APPING DSCP
P RIORITY
Use the Traffic > Priority > IP DSCP to CoS page to map IP DSCP priorities
found in ingress packets to CoS values for internal priority processing.
CLI R EFERENCES
◆ "map ip dscp (Global Configuration)" on page 1162
◆ "map ip dscp (Interface Configuration)" on page 1164
◆ "show map ip dscp" on page 1167