PON OLT Line card on a Chip
Delivery of high speed IP access for Quad Play services to the home and office environment is taking off and GPON and EPON technologies and solution will take a dominant rule in this path. These applications need to overachieve supporting higher data rates, using less power, and integrating more functions on a line card.
With the new requirements of TR-101 and connectivity to Metro Ethernet transport, a PON OLT line card solution shall include Network processing, advanced traffic management functionality and PON Framer:
However current OLT PON line card solution doesn't designed for mass adoption of FTTH services , as they are built based on a very expensive solution , which may include Traffic Manager , Network processor and Quad PON framer together with on board expensive SERDESs.
Following is a break down of the functionality per function:
- Networking functions:
- L2/L3 Bridging / switching/ forwarding
- VLAN, stacked VLAN, untagged, QTAG
- HW-based learning/ageing
- L2 to L5 Filtering and Access Lists
- TR-101
- IGMP Snooping
- DHCP
- PBT, MAC in MAC
- Multicast Forwarding
- Traffic Management functions:
- QoS Filtering, Coloring and Metering
- Per flow Policing, and shaping
- Hierarchical QoS
- PON Framer Function
- Ingress packet reassembly
- Ethernet GEM Adaptation Layer
- Logical Egress Port Queues
- GPON Framing
- DBA
- Encryption
Ethernity's first generation ENET4000/PON FPGA Access Flow Processor designed to fully support OLT EPON or GPON applications, and comes with User side interface selection of 8 x 1Gbps SGMIIs for EPON, or 4x 2.5G SGMII for GPON together with XAUI 10G for backplane/ up link connectivity. The ENET4000/PON Access Flow Processor support all the required Networking and Traffic management functionality at 15Gbps, and include integrated SERDESs for direct connectivity to Fiber Transceivers.
Figure 1: First Generation ENET4000/PON
Moving towards Single OLT line card on a chip
The ENET architecture inherently support most of the PON framer functionality on the same FPGA without the need to add more logic, thus enable the support of a full PON OLT line card solution on a single FPGA.
- GPON frames Reassembly: The ENET is a fragment frame switch and as part of this inherently can perform the entire GPON frame reassembly without the need for additional logic
- GEM Header: The ENET architecture include wirespeed packet editor , which can support any Ethernet Header and Encapsulation, together with stamping bit/bytes any where in the header, which can be used to stamp grant or gate messages
- Logical Egress port queues: the ENET hierarchical scheduler can maintain queue per flow, hence inherently can maintain queue per remote ONU
- Identify DBA information: the ENET field decoding engine can decode any data within incoming frame.
However the above only provide 90% of the functionality, while still there is a need to support unique PON functions like ranging, encryption, PON management and PON framing, which can easily integrated into the same FPGA by the integration of available customer (system or semiconductor) OLT MAC PON technology into a single OLT line card chip on FPGA, through Ethernity's customization services, which can later converted to ASIC / Hard copy.
Figure 2: PON OLT on a single FPGA
Note: The ENET 4000 is covered by six patents and based entirely on Ethernity technology, including Patented search engine, patented DDR controller, Patented Ethernet MAC,10G Ethernet MAC, traffic management and the entire pipe line network processing architecture.
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