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GPON & GEPON Comparison table

GPON GEPON COMPREHENSIVE COMPARISON TABLE

Comparison GPON GEPON
GPON GEPON Basics
  • ITU Standard G.984
  • ITU Standard G.987 for 10Gbits
  • Downstream 10Gbits/s, Upstream 2.488/10Gbits/s
  • Uses GPON Encapsulation Method (GEM), fragmented packets or ATM (most implementations use GEM as ATM is expensive)
  • Sometimes called GEPON (Gigabit Ethernet Passive Optical Network)
  • IEEE 802.3 standard, ratified as 802.3ah-2004 for 1Gbits/s
  • IEEE 802.3av standard for 10Gbits/s
  • Uses standard 802.3 Ethernet data frames
GPON GEPON Link Speed
  • GPON 2.448 Gbpsin the downstream direction and 1.24416 Gbpsin the upstream direction,
  • GPON in GEM mode can achieve ~ 95% efficiency of its usable bandwidth
  • GPON G.987 and EPON 802.3av are the same link speed EPON can scale via 802.3 standards 1Gbits/s, 10Gbits/s, etc.
  • GPON OLTs connect to the provider network using ATM switches or convert to Ethernet
  • whereas EPON is symmetrical 1.25 Gbps(1.0 Gbpsprior to 8B/10B coding)
  • EPON efficiency reaches 97.13% to 98.92% of the efficiency of a point-to-point 1GbE link. While
  • EPON can be operated in what is typically termed ‘turbo mode’ – downstream EPON data rate is doubled to 2.5Gbps, thus enabling bandwidth throughput comparable to GPON. EPON OLTs connect to the provider network using cost-efficient devices, such as Ethernet switches and routers.
  • Ethernet switches and routers use 802.3 as their standard as does EPON
GPON GEPON Splitting Ratios
  • GPON defines an upper limit
  • Promises to support 128 (with FEC)
  • Typical split ratio is 64
  • Standard supports a minimum of 32 but no upper limit
  • Split ratio defined by the services and bandwidth the provider wants to support
  • Typical split ratio is 32 and 64 with FEC
  • EPON can deploy cheaper optics at the ONU as it does not need to reach a split ratio of 128
GPON GEPON Similarities
  • Both have an Optical Line Terminal (OLT) at the headend
  • Both use passive optical splitters in the Optical Distribution Network (ODN)
  • Both have multiple Optical Network Units (ONUs) or Optical Network Terminals (ONTs) at the subscriber
  • Both utilize WDM: 802.3ah/ITU G.984 Downstream 1490nm, Upstream 1310nm, 802.3av/ITU G.987 Downstream 1260-1280nm, Upstream 1575-1580nm
  • Standards define different loss budgets but typically use 28dB which corresponds to 32 split at 20km
  • Forward Error Correction (FEC) is used to gain more loss budget
  • Both provide support for Voice, Video and Data
GPON GEPON Differences
  • GPON Provides native support for different services. As this is an ITU standard it is aimed at Telcos
  • Provides ATM for Voice
  • Ethernet for Data
  • Proprietary Encapsulation for other voice services
  • GPON equipment requires multiple protocol conversions, segmentation and reassembly (SAR), virtual channel (VC) termination and Both utilize a common optical infrastructure, but very different in execution. EPON extended point-to-point protocol (PPP)
  • EPON assumes that data today starts and ends as Ethernet and therefore 802.3 frame format is appropriate. Used widely in the Enterprise and Asian ISP markets.
  • IP data services
  • VoIP
  • IPTV – Supports multicast so uses less bandwidth
GPON GEPON Layering GPON on the other hand is fundamentally a transport protocol, wherein Ethernet services are adapted at the OLT and ONT EPON is based upon IEEE 802.3 modified to support Point-toMultipoint (P2MP) connectivity. Ethernet traffic is transported natively and all Ethernet Features are fully supported.
GPON GEPON Framing GPON-GEPON-comparison---GPON-Frame GPON-GEPON-comparison---GePON-Frame
GPON GEPON Costs
  • xDSLstill widely deployed but moving to PON
  • ATM devices supporting DSL and GPON expensive and being replaced with Ethernet devices
  • North American Telcos have historically used GPON
  • No native support for Multicast so uses proprietary solution or more bandwidth
  • Timing constraints tighter with GPON so optics more expensive GPON adds a layer of complexity to data networks (including VoIP), as traffic must be converted to IP
  • Approximately 60% of PON subscribers worldwide Scale reducing cost and driving investment
  • North American Cable Operators also moving to EPON
  • Ethernet devices approximately 1/10 the cost of ATM devices Optics less expensive than GPON
GPON GEPON Summary
  • Both EPON and GPON recognized the need to evolve PON to being a Gigabit capable solution for transporting Ethernet IP traffic.
  • native Ethernet to support the PON P2MP architecture, while GPON wished to extend the life of GFP framed SONET/SDH GPON link rates match ITU standards like OC3, OC12, etc
  • North American Telcos SONET/GPON Equipment based on ITU/SONET typically more expensive/complicated
  • Both utilize a common optical infrastructure, but very different in execution. EPON extended
  • EPON link rates match IEEE standards like 1Gbs, 10Gbs, etc
  • North American Cable Operators adopting EPON
  • EPON is widely deployed world-wide
  • Ethernet and IP scale reducing costs and driving investment in EPON systems
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