Alcatel-Lucent 9500 MXC User Manual page 445

3DB 23063 ADAA - Rev 004 July 2007
Item Description
2 Priority Table. Presents the priority mapping used to convert the 8 priority
levels of 802.1p and the 63 levels of DiffServ to the 4 levels supported by the
DAC ES priority stack: high, medium high, medium low, and low.
The mapping shown is default mapping for 802.1p.
To change mapping click and select from the Internal priority sub-menus.
3 Set Defaults returns priority mapping to its default settings.
4 Select All selects (highlights) all rows. Fill Selection sets all selected
(highlighted) rows to the mapping set in the top-most row.
Priority Mode Options
• Port Default sets the queue controller priority on a port basis - it ignores
any 802.1p VLAN priority tags or IP DiffServ priority values on incoming
traffic. Port priority settings are made per-port in the Priority column in
the Configuration window. Refer to Step 5.5.
The settings support four-level port prioritization, which is weighed on a
8:4:2:1 basis whereby a port set for high priority has packets sent 2-for-1,
4-for-1, or 8-for-1 against the medium high, medium low, and low priority
settings respectively. Compared to a fixed priority where all higher priority
packets must be sent before others, the weighed solution guarantees that
lower priority port queues do get some bandwidth.
• 802.1p provides prioritization based on the three-bit priority field of the
802.1p VLAN tag. Each of the possible eight tag priority values are
mapped into a four-level (2-bit) priority level. Refer to Table 7-7. If
packets are not tagged then the Port Default prioritization will apply to
these packets.
• DiffServ provides prioritization based on the six bits of the IP packet
DiffServ or Type of Service byte. Each of the possible 63 levels are
mapped into a four-level (2-bit) priority level. Refer to Table 7-7. If
packets are not tagged, then the Port Default prioritization will apply to
these packets.
• 802.1p then DiffServ provides prioritization based first on the 802.1p
VLAN tag, and then on the DiffServ or Type of Service byte. If packets
are not tagged, then the Port Default prioritization will apply to these
packets.
• DiffServ then 802.1p provides prioritization based first on the IP packet
DiffServ or Type of Service byte, then on the 802.1p VLAN tag. If
packets are not tagged, then the Port Default prioritization will apply to
these packets.
9500 MXC User Manual
Vol. IV-7-55