3com S7906E 설치 설명서
1-2
Figure 1-1
A typical EPON architecture
ODN
OLT
POS
ONU2
ONU1
ONUn
OLT
An OLT, generally an Ethernet switch, router, or multimedia conversion platform, is located at the central
office (CO) as a core device of the whole EPON system to provide core data and video-to-telephone
network interfaces for EPON and the service provider.
office (CO) as a core device of the whole EPON system to provide core data and video-to-telephone
network interfaces for EPON and the service provider.
ONU
ONUs are used to connect the customer premise equipment, such as PCs, set-top boxes (STBs), and
switches. Generally placed at customer's home, corridors, or roadsides, ONUs are mainly responsible
for forwarding uplink data sent by customer premise equipment (from ONU to OLT) and selectively
receiving downlink broadcasts forwarded by OLTs (from OLT to ONU).
switches. Generally placed at customer's home, corridors, or roadsides, ONUs are mainly responsible
for forwarding uplink data sent by customer premise equipment (from ONU to OLT) and selectively
receiving downlink broadcasts forwarded by OLTs (from OLT to ONU).
ODN
An ODN consists of optical fibers, one or more passive optical splitters (POSs), and other passive
optical components. ODNs provide optical signal transmission paths between OLTs and ONUs.
optical components. ODNs provide optical signal transmission paths between OLTs and ONUs.
A POS can couple uplink data into a single piece of fiber and distribute downlink data to respective
ONUs.
ONUs.
Benefits of the EPON Technology
Lower operation and maintenance costs
Compared with a traditional Ethernet broadband access network, an EPON network greatly lowers the
operation and maintenance costs. This is because, as passive equipment in an EPON system, POSs
are energy-saving (requiring no power supply), highly reliable (not affected in case of a power outage),
and easy to install, and save optical fiber resources.
operation and maintenance costs. This is because, as passive equipment in an EPON system, POSs
are energy-saving (requiring no power supply), highly reliable (not affected in case of a power outage),
and easy to install, and save optical fiber resources.
Long distances and higher bandwidths
Compared with an Ethernet broadband access network, an EPON system provides a longer access
transmission distance (up to 20 km, or 12.43 miles) and higher bandwidth (1 Gbps) that can adapt to the
service status of the ONUs in real time. Each ONU enjoys dedicated line quality similar to Time Division
Multiplexing (TDM) with dedicated uplink bandwidth in the grant cycle assigned to it.
transmission distance (up to 20 km, or 12.43 miles) and higher bandwidth (1 Gbps) that can adapt to the
service status of the ONUs in real time. Each ONU enjoys dedicated line quality similar to Time Division
Multiplexing (TDM) with dedicated uplink bandwidth in the grant cycle assigned to it.