G.709 -> frame structures / G.872 -> architecture / G.798 -> management functions etc.)
A multiplex hierarchy of transport containers (optical data units - ODUs - organized in optical transport units - OTUs) provides the base for GFP framed or transparent data services.
OTU containers are numbered by 1 .. 4 reflecting the following data rates:
- OTU1 / ODU1 for 2.5 gbps
- OTU2 / ODU2 for 10 gbps
- OTU3 / ODU3 for 40 gbps
- OTU4 / ODU4 for 120 gbps
The OTU4 container specification is currently under way and seems to me the ITU-T answer for the 100 gbps effort at the IEEE HSSG.
OTU-4 containers will be capable to transparently transmit either 9 times 10 GE signals or one 100GE signal.
100 Gigabit Ethernet will certainly transport 100.000.000.000 bits per second, which is 12.500.000.000 bytes per second.
The Ethernet frame format, which will remain untouched by the HSSG work consists of 6 byte destination address, 6 byte source address, 2 byte type filed, 4 byte crc and minimal 46 or typical 1500 byte payload. The resulting frame size varies from 64 byte per frame to 1518 bytes per frame.
If we assume a 1500 byte payload field to be used in 100GE framing, we end up with 12.500.000.000 bytes / 1500 payload bytes per Ethernet frame = 8333333,33 frames.
Hence we need to transmit 8333334 frames per second, which sums up to 8333334 frames per second * 1518 bytes per frame = 12650001012 bytes per second.
Finally, we calculate the bit rate to 101200008096 bps for the actual frame transport.
In transparent transport mode, we will also transmit preamble and SFD bits, which add another 8 byte to each frame on the transport stream. (8 * 8 * 8333334 = 533333376 framing bits per second)
This results in 101.733.341.472 bps to be carried in ODU-4 units.
Please inform me, if my calculation is to be corrected as well as when the actual OTU-4 standardization has completed.
