3Com 3C17300-US - SuperStack 3 Switch 4226T, Implementation Manual

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How Traffic Prioritization Works 53
You cannot alter the mapping of priority levels 0 - 7 to the traffic queues.
These priority levels are fixed to the traffic queues as shown in
Figure 13 .
Figure 13 IEEE 802.1D traffic types
Figure 13 illustrates IEEE 802.1D traffic types as well as associated priority
levels and how they are mapped to the two supported traffic queues.
The 802.1D service level of the packet is not altered by the Switch 4200
Series.
DiffServ traffic
classification
DiffServ is an alternative method of classifying traffic so that different
levels of service can be applied to it on a network. DiffServ is a layer 3
function; and the service to be applied is contained within the DSCP field,
which is in the IP header of a packet.
802.1p
Service levels
Classification
802.1D
Low Priority Queue
Egress Port
Best effort
Background
Spare
Business Critical
Multimedia
Video
Voice
Network Control 7
6
5
4
3
2
1
0
High Priority Queue
Ingress Port
Strict Priority
Queue Scheduling
dua1730-0bAA03.book Page 53 Monday, July 11, 2005 11:14 AM