overflows. In case the ingress buffer fills above a certain threshold, pause messages are
sent in the reverse direction to hold off further traffic. This behaviour improves the
TCP throughput. Note that Pause messages are only sent when the Pause mode is
enabled via the Lucent NMS.
Auto-negotiation
The EPL4_E132_75 option card supports Auto-negotiation. The Auto-negotiation
function automatically configures the Ethernet interface parameters to establish an
optimal Ethernet link based on the capabilities of the near-end and far-end Ethernet
interfaces.
Auto-negotiation for twisted-pair systems, defined in Clause 28 of the Standard
802.3-2002, has been extended to include all three speeds of Ethernet that are
supported over twisted-pair cable: 10Mbit/s 10Base-T, 100Mbit/s 100Base- TX, and
1000 Mbit/s 1000Base-T. For more information about Auto-negotiation support, please
refer to the Metropolis
®
AMU User Operations Guide.
Link Pass Through (LPT)
The EPL4_E132_75 option card supports the Link Pass Through (LPT) mode. On
point-to-point Ethernet Private Line connections, when GFP data encapsulation is used
throughout the network, the system identifies defects from the network ingress port to
the network egress port. The GFP-CSF mechanism is used to notify the egress side that
a loss of signal (synchronization) has occurred on the ingress port. An alarm is raised
at the egress side which indicates the ingress side condition. For more information,
please refer to (see LPT,
). For additional information, please also refer
to the TransLAN® Ethernet SDH Transport Solution Applications and Planning Guide.
The EPL4_E132_75 option card supports Auto MDI/MDIX selection on all LAN ports.
Transmission rates
The following rates are supported with EPL4_E132_75:
•
Mapping Ethernet packets into VC12-Xv (X = 1...63)
•
Mapping Ethernet packets into VC3-Xv (X = 1...9)
•
Mapping Ethernet packets into VC4-Xv (X=1..7)
Flexible bandwidth assignment
The transmission capacity of the EPL4_E132_75 option card towards the cross-connect
matrix is 9 x VC-4s. One VC-4 is reserved for the 32 E1 ports and is not available for
the VCGs. The remaining 8 VC-4s can be freely assigned to 4 VCGs. There is a fixed
1:1 relationship from the 4 Ethernet ports to the 4 VCGs. For an illustrated description,
see (see fig. on page 2-17).
From the 8 VC-4s, two can be individually substructured to VC-12s, thereby providing
upto 2 x 63 VC-12s. In this case, the first 4 VC-12s of the first VC-4 remain unused.
In addition, 3 VC-4s can be individually substructured to VC-3s, providing a total of 9
VC-3s. The remaining 3 VC-4s cannot be substructured. For each of the 4 VCGs, a
Product description
Introduction
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2-20
Lucent Technologies - Proprietary
See notice on first page
365-312-847R4.0
Issue 4, November 2006