OTN Learning notes-frame rate

1) Otuk (k=1,2,3,4 ...) frame rate

Unlike the Sdh/sonet basic 8K frame cycle, with the increase of the line rate, the structure and length of the g.709 frame are constant, and the frame cycles of different rate classes of OTN are not the same.
OTU1 48.971us
OTU2 12.191us
OTU3 3.035us

The frame rate of OTN is specifically designed for SDH, where OPUK frames can be fitted with SDH frames of the same rate grade or multiple low-rate odui (i<k) frames.
Therefore, the OTU frame rate calculation formula can be obtained according to the OTU frame structure and stm-n mapping to Out mode:
1 x Otu frame 4080*4 bytes (=255*16*4);
OPU payload occupies (3824-16) *4=3808*4 bytes (=238*16*4)

OPU1 is exactly the rate of STM-16 2 488 kbit/s;
odu1= (3824/3808) *opu1= ((239*16)/(238*16)) *opu1= (239/238) * * 488
otu1= (4080/3808) *opu1= ((255*16)/(238*16)) *opu1= (255/238) * * 488

OPU2 contains 16*4=64 fixed padding bytes (FS) added to 1905~1920 column
Opu2* ((238*16*4-16*4)/(238*16*4) = rate of STM-64;
opu2= 238/(238-1) * STM-64 = 238/237 * 9 953 280 kbit/s;
Odu2= (239/237) * 9 953 280 kbit/s;
Otu2= (255/237) * 9 953 280 kbit/s;

OPU3 contains 2*16*4=128 fixed padding (FS) bytes added to 1265~1280 columns and 2545~2560 columns
opu3* ((238*16*4-2*16*4)/(238*16*4) = rate of STM-256;
opu3= 238/(238-2) * STM-256 = 238/236 * 813 * KBIT/S;
odu3= (239/236) * 813 kbit/s;
otu3= (255/236) * 813 kbit/s;2) Ho/lo OTN architecture

The high-order/low-order optical channel architecture not only enables the compatibility of traditional OTN architectures, but also enhances OTN's ability to adapt to mainstream business, such as Ethernet services.
OTN currently regulates 4 levels of line rate 2.5G (ho ODU1), 10G (Ho ODU2), 40G (Ho ODU3, odu3e1/odu3e2) and 100G (Ho ODU4).
The LO Oduk can be directly out of wavelength or further multiplexed into Ho Oduk.
For Ho Oduk, 1.25G of time slot particles are further expanded on the original 2.5G timeslot, enabling the new Otn to support ODU0 bandwidth particles.
The 1.25G and 2.5G timeslot structures are identified using different net load types.

Otn currently supports 1GE, 10GE, 40GE, and 100GE transmissions.
GE and 40GE services through the coding compression scheme, respectively mapped to ODU0 and ODU3, 10GE through bit synchronization mapping to Opu2e,100ge multichannel interface through 64b/66b code word recovery, channel alignment after mapping to OPU4.


3) General mapping procedure GMP

The traditional OTN recommendation only defines the adaptation schemes for CBR (fixed bit rate) business, GFP Business, and ATM services.
At present, the transmission of customer signals has three levels of transparency: frame transparency, code-word transparency and bit transparency.
The frame transparency method discards the preamble and frame gap information, which may carry some private use.
Similarly, the code-word transparency method can also disrupt the original information of the customer signal.
For multi-service bit transparency requirements, OTN defines a common mapping protocol GMP to support multi-service hybrid hosting.
GMP is able to automatically calculate the number of customer signals that need to be carried in each service frame, based on the customer signal rate and the rate at which the service layer transmits the channel, and is distributed to the service frame.
GMP can realize the automatic adaptation of CBR business to Otn container, and it is the key technology of OTN carrying multi-service.

4) Oduflex

For the future of the various rate-level business, defined two variable rate Oduflex container,
One is based on CBR business Oduflex, this Oduflex rate has 3 range segments, respectively ODU1 to ODU2, Between ODU2 and ODU3 and ODU3 to ODU4, this Oduflex is adapted to the CBR business by synchronizing the mapping of BMP.
Another is based on the package business of Oduflex (GFP), the rate of Oduflex (GFP) between 1.38~104.134g, the rate of Oduflex (GFP) is arbitrarily variable in principle, However, ITU-T recommends using multiples of the Oduk time slot to determine the rate, which Oduflex (GFP) is suitable for packet business through GFP. The
Oduflex and Oduk (k=0,1,2,2e,3,4) Form a low-order transport channel that supports multiple services and can cover all businesses within the 0~104G range. Oduk (k=0,1,2,2e,3,4), based on the mainstream Ethernet and SDH business definition, can provide optimal bandwidth utilization for the mainstream business, while Oduflex provides a useful complement to the delivery of other services, enabling some non-mainstream business.