PLANET XGS3-24042 - Manual (Page 653)

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pre-configured service policy to different services, ensuring the service quality.
The service quality class mechanism and the label mechanism of Diff-Serv are similar to the label distribution
mechanism of MPLS. In fact, the MPLS-based Diff-Serv is implemented via the combination of the DS
distribution and MPLS label distribution.
79.1.5 MPLS PHP
In the MPLS network, the core LSR will forward packets according to their labels. The Egress router (Egress
LER) will remove the label before implementing IP forwarding.
In fact, in simple MPLS applications, where the Egress routers only implement IP forwarding, labels will
become useless. In such cases, popping the labels out via the Penultimate Hop Popping feature at the
penultimate router will stop the Egress router from processing the labels.