IEEE 802.1Q VLAN tagging
mode without encoding of the
dropping precedence
The traffic class is encoded in the user priority bits
using p2, p1, and p0. Thus, 8 traffic classes are
defined: 0, 0-, 1, 1-, 2, 2-, 3, 3-. The “n” traffic
classes differ from the “n-” traffic classes in the
value of the p0 bit.
Notes:
1. The support of dropping precedence encoding and evaluation can be enabled or disabled
per virtual switch by means of the QoS_osub configuration parameter (QoS_osub =
enabled/disabled). All virtual switches belonging to the same TransLAN
®
network must
be provisioned equally for their TPID and this QoS_osub configuration parameter. These
tables show the traffic class encoding in the user priority bits:
With oversubscription:
Without oversubscription:
For the IEEE 802.1Q VLAN tagging mode with oversubscription support (QoS_osub =
enabled) it is recommended not to use the n- classes, otherwise all frames will always
be marked yellow (i.e. they will have a higher dropping precedence; p0 = 0). In the
provider bridge mode, any assignment of an n- class will be recognized as the related n
class (tolerant system behavior for inconsistent provisioning).
Traffic class p2
p1
0
1
2
3
1
0
0
0
0
1
11
Traffic class p2
p1
0
1
2
3
1
0
0
0
0
1
11
p0
1
0
0
1
0-
1-
2-
3-
1
0
0
0
0
1
11
1
0
0
1
Ethernet Overview
Classification, queueing and scheduling
....................................................................................................................................................................................................................................
11-60
Alcatel-Lucent - Proprietary
See notice on first page
365-312-801R7.2
Issue 3, May 2007
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