D-Link DXS-3600-16S, Руководство пользователя

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DXS-3600 Series 10GbE Layer 2/3 Switch CLI Reference Guide
374
Usage Guideline Use the class-map inbound command to set the mapping from EXP to have priority
for incoming packets. The inbound mapping takes effect only when trust-exp is
enabled. If inbound mapping exists, it will be replaced by the last configuration.
Use the class-map outbound command set the mapping from priority to EXP for
outgoing packets. If outbound mapping exists, it will be replaced by the last
configuration.
The follows figure shows the MPLS packet forwarding flow in the device.
Once MPLS packets is received, if there is an inbound EXP to priority mapping entry
for the FEC, the device will assign priority according to the inbound EXP. Otherwise,
the priority is assigned according to 802.1p.
The device then selects a CoS queue according to the priority set in the CoS
mapping rule. When the device transmits packets from the outgoing interface, if
there is outbound EXP mapping, the EXP will always set the rule according to the
mapping rule. If the incoming packets have an MPLS label, the EXP will not be
modified. If the incoming packets don’t have MPLS packets, the EXP will be set to
zero.
The follows table show the outbound EXP mapping summary:
If there is an outbound setting that maps a priority to an EXP and another setting that
maps all priorities to other EXPs, the setting that maps the specified priority has
higher priority. For example:
1 Class-map outbound priority 1 EXP 6.
2 Class-map outbound EXP 3.
Apply the QoS policy to FEC 10.1.1.0/24. Then if the outgoing MPLS packets for the
FEC have priority 1, the EXP will be set to 6. The EXP of other packets for the FEC
will be set to 3.
Use the no class-map inbound command to remove all inbound class-map
settings. Use the no class-map outbound command to remove all outbound class-
map settings.
0
P riority-CoS
mapping table
0
1 1
... . ..
7 6
0
Inbound EXP-P riority
mapping table
0
1 1
.. . . ..
7 7
0
outbound Priority-EXP
mapping table
0
1 1
... . ..
7 7
Incoming
MPLS packets
queues
1. Pick up priority
according EXP
2. Select queue
according priority to
CoS mapping
3. M odify EXP
according priority to
EXP mapping
Outgoing MPLS
packets
Incoming packet type Outbound EXP mapping
setting Outbound EXP
MPLS packets No setting Same as incoming EXP
No MPLS packets No setting 0
Any Mapping doesn’t care
about priority Set to specified EXP for all
matched packets
Any Mapping specify priority to
EXP Set to specified EXP only
for priority matched
packets.