Cambium Networks PTP 820S, Техническое описание, Страница: 54 / 208

Chapter 4: Feature Description Ethernet Features
Figure 24 E-Line Service Type Using Point-to-Point EVC
Ethernet Private Line Service
An Ethernet Private Line (EPL) service is specified using an E-Line Service type. An EPL service
uses a point-to-point EVC between two UNIs and provides a high degree of transparency for
service frames between the UNIs that it interconnects such that the service frame’s header and
payload are identical at both the source and destination UNI when the service frame is delivered
(L1 service). A dedicated UNI (physical interface) is used for the service and service multiplexing is
not allowed. All service frames are mapped to a single EVC at the UNI. In cases where the EVC
speed is less than the UNI speed, the CE is expected to shape traffic to the ingress bandwidth
profile of the service to prevent the traffic from being discarded by the service. The EPL is a port-
based service, with a single EVC across dedicated UNIs providing site-to-site connectivity. EPL is
the most popular Ethernet service type due to its simplicity, and is used in diverse applications
such as replacing a TDM private line.
Figure 25 EPL Application Example
Ethernet Virtual Private Line Service
An Ethernet Virtual Private Line (EVPL) is created using an E-Line service type. An EVPL can be
used to create services similar to EPL services. However, several characteristics differ between EPL
and EVPL services.
First, an EVPL provides for service multiplexing at the UNI, which means it enables multiple EVCs
to be delivered to customer premises over a single physical connection (UNI). In contrast, an EPL
only enables a single service to be delivered over a single physical connection.
Second, the degree of transparency for service frames is lower in an EVPL than in an EPL.
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