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W
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networks (WANs) that span large geographic areas. Allows, for example, mobile users
to dial up their company LANs.
W
WAN
Wide Area Network. A WAN typically serves users across a broad geographic area and
generally makes use of transmission devices provided by common carriers.
Technologies involved with WANs can include Integrated Services Digital Networks
(ISDNs), T1 networks, X.25, Frame Relay, and SMDS.
X
X-Bit Alarm
The two X-Bits in the frame are set to 00 and returned to the near end when there is an
SEF or AIS at the far end. Otherwise, they are set to 11.
Y
Y.1564
ITU-T Y.1564 defines a test methodology that may be used in assessing the proper
configuration and performance of an Ethernet network to deliver Ethernet-based
services. This out of-service test methodology was created so that service providers
may have a standard way of measuring the performance of Ethernet-based services.
Z
Z0 byte
Section growth byte. These bytes, which are located at positions S[1, 6N+2] to S[1, 7N]
of an STM-N signal (N>1), are reserved for future international standardization.
MPA_e_manual_D07-00-129P_RevA00