Cambium Networks PTP 820S, Техническое описание, Страница: 49 / 208

Chapter 4: Feature Description Ethernet Features
Figure 18 Basic Ethernet Service Model
In this illustration, the Ethernet service is conveyed by the Metro Ethernet Network (MEN) provider.
Customer Equipment (CE) is connected to the network at the User Network Interface (UNI) using a
standard Ethernet interface (10/100 Mbps, 1 Gbps). The CE may be a router, bridge/switch, or host
(end system). A NI is defined as the demarcation point between the customer (subscriber) and
provider network, with a standard IEEE 802.3 Ethernet PHY and MAC.
The services are defined from the point of view of the network’s subscribers (users). Ethernet
services can be supported over a variety of transport technologies and protocols in the MEN, such
as SDH/SONET, Ethernet, ATM, MPLS, and GFP. However, from the user’s perspective, the
network connection at the user side of the UNI is only Ethernet.
EVC
Subscriber services extend from UNI to UNI. Connectivity between UNIs is defined as an Ethernet
Virtual Connection (EVC), as shown in the following figure.
Figure 19 Ethernet Virtual Connection (EVC)
An EVC is defined by the MEF as an association of two or more UNIs that limits the exchange of
service frames to UNIs in the Ethernet Virtual Connection. The EVC perform two main functions:
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