Service Egress and Ingress QoS Policies
Quality of Service Guide 203
Figure 15: DE Aware 802.1ad Access Network
The following shows an example of the QoS processing in more detail.
Figure 16 displays a simple example of the DEI processing steps for the IEEE 802.1ad Use
Case for both ingress and egress directions (from a PE1 SAP perspective).
Figure 16: DEI Processing Ingress into the PE1 SAP
The following steps related to DEI are involved in the QoS processing as the packet moves
from left to right:
1. The QinQ access device sets the DE bit from the STAG based on the QoS
classification or on the results of the metering/policing for the corresponding
customer UNI.
2. The SAP on PE1 may use the DE bit from the customer STAG to classify the frames
as in/out of profile. Color aware policing/metering can generate addition out of
profile packets as the result of packet flow surpassing the CIR.
3. When the packet leaves PE1 via SDP, the DE indication must be copied onto the
appropriate tunnel QoS fields (outer VLAN ID and or EXP bits) using the internal
PHB (per hop behavior) of the packet (for example, the FC and Profile).
4. As the packet arrives at PE2, ingress into the related SDP, the DE indication is used
to classify the packets into an internal PHB.
5. Egress from the PE2 SAP, the internal PHB may be used to perform marking of the
DE bit.
UNI
Fig_26
802.1 a/d
Access
(DE aware)
Access
Device
MPLS
7x50 PE2
I-SAP
CE
SDP
CE
7x50 PE1
SDPSAP
1
Fig_28
802.1 a/d
Access
(DE aware)
Access
Device
SAP Ingress SDP Egress SDP Egress SAP Egress
MPLS
7x50 PE2
4 5
7x50 PE1
32
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