Alcatel-Lucent 9500 MXC User Manual page 463

3DB 23063 ADAA - Rev 004 July 2007
802.1p VLAN tag. DAC GE maps each of the possible eight priority tag
values into a four-level (2-bit) priority field. Refer to Table 7-8 for default
mapping assignments.
• DiffServ provides prioritization based on the six bits of the IP packet
DiffServ or Type of Service byte. DAC GE maps each of the possible 63
levels into a four-level (2-bit) priority field. Refer to Table 7-8 for default
mapping assignments.
• If No Priority is selected DAC GE will pass packets transparently; it will
not assign a priority on incoming untagged or tagged packets.
• Data is forwarded on a strict priority basis - all high priority packets are
forwarded before any lower-level packets.
• The same four-level low to high prioritization mechanism is used to
prioritize ingressing VLAN tagged traffic against untagged traffic that is
subject to port priority. If ingressing VLAN tagged frames are to be
accorded priority over untagged traffic then the mapping used to assign a
priority to the VLAN tagged frames must be set to a higher level than that
for port priority in the DAC GE Configuration screen.
DAC GE Priority Mapping Table
Table 7-8.
DAC GE 802.1p
Priority Level Priority
High
Medium High
Medium Low
Low
• To change mapping assignments, click and select on the relevant Internal
Priority sub-menus.
• To return mapping to default, click Set Defaults.
14. VLAN Tagging: Click the VLAN Tagging tab to view the options.
DAC GE supports 802.1q tagging with menus for selection of VLAN
tagging modes, and priority settings for tagged-traffic. Diagrams assist
understanding of the tagging action for each mode; refer to Figure 7-27 and
to Figure 7-28.
• The tagging options are Do Nothing, Q-in-Q, or 802.1q.
• Selections are made on a per-port basis.
• With Q-in-Q, frames with existing tags are tagged (double tagged).
• With 802.1q untagged frames are tagged.
DiffServ
Priority
6, 7 48 - 63
4, 5 32 - 47
2, 3 16 - 31
0, 1 0 - 15
9500 MXC User Manual
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