Item
DS1/E1 WAN interfaces
DS1/E1 CES over Ethernet layer 2
GPON
DS1 standards
E1 standards
Synchronization
Note
(1)
The upstream derived clock that is provided by the P-OLT is tied to the BIT clock and must be
traceable to a network timing reference. The derived clock is used for differential clock recovery
and for timing the upstream PWE3 packet streams in the absence of a valid TDM recovery clock.
CES Overview
Circuit Emulation Services (CES) encapsulation is supported on DS1 and E1 TDM
traffic for transport as Ethernet layer 2 over the GPON using the Metro Ethernet
Forum standard MEF-8 payload structure and pseudo-wire (PW) technology. CES
and the DS1 or E1 ports may be provisioned on the business ONT using a TL1 or an
EMS management session with the P-OLT.
The business ONT supports DS1 and E1 service connections at the subscriber
premises. The following TDM link types are supported:
•
structured (fractional) DS1 or E1
•
unstructured DS1 or E1
At the subscriber premises, the business ONT terminates DS1 or E1 links from the
subscriber. The TDM traffic is adapted and packetized using MEF-8 pseudo-wire
technology before being transported across the GPON. MEF-8 is the payload option
that is used. The MEF-8 packets are multiplexed with the Ethernet layer 2 data traffic
at the business ONT GPON port.
When the MEF-8 packets are received at the OLT, the packets are forwarded to the
destination PSTN, typically via a voice gateway that is connected to the IP network.
Figure
Alcatel-Lucent 7330/7302 ISAM FTTN R04.02.42a
3FE 54199 AAAA TCZZA
3 — ONT and MDU general and interface technical specifications
Table 3-6 DS1/E1 interface specifications
CES DS1/E1
Gigabit
Ethernet
3-2
shows the traffic flow.
Edition 01 ONT Product Information Guide
Specification
Two RJ-48C ports configured for 100 Ω DS1, 120 Ω balanced E1,
or 75 Ω unbalanced E1. An external adapter is required for 75 Ω.
MEF-8 packetization as IETF PWE3 pseudo-wires
AT&T TR-6421; ITU-T Rec. G.703, G.704
Structured (fractional) and unstructured DS1
ITU-T Rec. G.703, G.704, G.706, G.732, G.823
Structured (fractional) and unstructured E1
Upstream: A 16.384 MHz local oscillator or a derived clock
from the GPON that is provided by the P-OLT
Downstream: Either a 16.384 MHz adaptive clock received from
the PWE3 packet stream or a differential clock recovered from
the PWE3 packet stream
A Gigabit Ethernet transmit reference clock of 125 MHz as per
IEEE 802.3
March 2011
(1)
3-11