Alcatel-Lucent 1643 AMS - Page 441

Default user priority
A default user priority can be configured for each customer-role port. Possible values
are 0 (lowest priority) { 7 (highest priority) in steps of 1. The default setting is 0.
Provisioning of the default user priority does not apply to network-role ports.
The default user priority is treated differently depending on the tagging mode:
• LAN-VPN (M-LAN) mode
Incoming frames without a user priority encoding (untagged frames) are treated as
if they had the default user priority.
• IEEE 802.1Q VLAN tagging mode and provider bridge mode
Incoming frames without a user priority encoding (untagged frames) get a default
user priority assigned. This C-UP may be further on equal to a user priority given
by one of the provisioned flow descriptors. The subsequent traffic class assignment
for this flow, however, will overwrite this C-UP bits again.
Traffic classes
At each ingress port, the traffic class (TC) for each frame is determined. At
customer-role ports, this is done via the flow identification and the related provisioned
traffic class. At network-role ports, the traffic class is directly derived from the p-bits
of the outermost VLAN tag.
Depending on the operation mode, these traffic classes exist:
Provider bridge mode and IEEE
802.1Q VLAN tagging mode
with encoding of the dropping
precedence
The traffic class is encoded in the user priority bits
using p2 and p1. Thus, four traffic classes are
defined: 0, 1, 2, 3.
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, eight 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:
Traffic provisioning Classification, queueing, and scheduling
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365-312-807R7.2
Issue 4, May 2007
Alcatel-Lucent - Proprietary
See notice on first page
8-89