The first thing to talk about is the concept of TDM. TDM is time-division multiplexing, which divides a standard duration (1 second) into small segments (8000), and transmits one signal every hour (1/8000=125us). ; The circuit scheduling of SDH system is based on TDM, so many people say that SDH service is TDM service, which is the traditional circuit scheduling, which has theoretical basis; However, when SDH was in full swing, another battle between Ethernet and ATM (not a cash machine), Ethernet achieved a complete victory, and Ethernet became popular. Among them, IP was the strongest, resulting in many business side today. IP, can't help but say Ethernet is too XXXXX. Question: SDH is a big red man. Ethernet is another big red man. Can you cooperate? ? ? It was a hit, MSTP was born! The share allocation in the joint venture company MSTP is not uniform: SDH accounts for 70% of the shares, Ethernet accounts for 20% of the shares, and other companies include 10% of the shares of the ATM. The power is still SDH, the kernel is still TDM, and all the disadvantages of TDM are still retained. Such as rigid pipelines; Ethernet and ATM have not come up with decent things because of equity issues, just have their tables (providing the corresponding interface) With the popularity of the Internet, computers, mobile phones, televisions and other terminals can access the Internet. The demand for bandwidth has increased sharply. The opportunities for telecom operators to make money have come, but the challenge has come. Previously, 1*155M could provide thousands of dollars. People call, now people have to go online when they call, bandwidth demand grows and there is a contradiction in the resources of the current network. To solve this contradiction, let's take a look at how SDH, the red man, usually gets along with others: SDH, the red man has always been my own way, but I am the only one, never sharing public resources with others, such as the second ring to give me a run, the second ring will not allow other vehicles to pass, the above is my car, just started, my car Can pull 1 guest (STM-1), then the efficiency of the second ring is to transport a person (155M--STM-1), and later upgraded the tonnage, I can pull 64 guests (64*STM-1) , then the efficiency of the second ring is (10G-STM-64), this is the ring rate; currently the maximum is 40G If there is no time for people to transport, then I will run empty, look at the scenery, beautiful women along the way, then the efficiency is 0, other roads are blocked and I have no relationship, because of more stubborn, I also have A lot of helplessness, for example, your car can hold 64 guests, but now there are 65 guests, sorry, I can only transport 64 people, we call this inefficient operation method rigid pipe There are more and more guests who need to ship now, but they are too busy. There are three ways to solve this problem: The first type: repair several roads (new fiber optic cable) for personnel diversion; disadvantages: cost and cycle is too long --------PASS The second type: upgrade the car tonnage (increased rate); Disadvantages: the car factory has not developed a vehicle with a larger load (limited electronic components) - PASS The third type: dividing the second ring into multiple lanes (channels), multiple vehicles sharing roads Immediately after the leadership looked at it, the plan 3 was feasible and implemented immediately! Wave division Wavelength division WDM is to transfer vehicles (signals) of multiple lanes (channels) to the same road (fiber) for transmission. There are two types according to the lane separation size: The lane spacing is 20nm, which is sparse wave division, also known as coarse wave division; Dense wavelength division for lane separation less than or equal to 0.8 nm This bandwidth has been multiplied, temporarily solving the problem of insufficient bandwidth! I can rest and rest............ After WDM is reused, the localities have followed suit. The current WDM is not only used in urban main roads (metropolitan wavelength division), but also used on cross-city and inter-provincial roads (long-distance wave division); Its specific way of working is that all types of cargo or passengers (business signals) are loaded into a car, the car is driven according to a pre-allocated lane (channel), the middle car needs to be refueled, and we also set up a gas station ( Light station OLA), the passengers need to eat and rest to replenish their strength, we set up a temporary rest area (relay station) for them, of course, we still can not do without the support of the traffic police system (light monitoring OSC or electric monitoring ESC) As people's needs continue to increase, the number of lanes has been expanded from the first 16 or 32 to 40, 80, 160. The current construction level (manufacturing process) has exceeded 200 lanes (channels), but our management The level is still very low, mainly reflected in the following aspects: 1. Traffic management message is not smooth (OAM lack): The original intention of WDM is to solve the problem of insufficient bandwidth. After considering the increase of bandwidth, management must keep up with it. Now the biggest problem is that there are more vehicles, how to each The state of the car is well known, and the traffic police (OSC) feels powerless; at this time, several SDH crew members are whispering: Our SDH bus system has a unified management organization, and each driver has a driver and Ticket sellers, clear division of labor, also use real-time video surveillance (online monitoring), the company can always understand the health of each car, WDM you are too far away 2, scheduling is not flexible: WDM has a serious flaw at the beginning of design: for example, a cargo to be transported from Xi'an to Beijing, the pre-allocated lane is 10 lanes (10th wave), then the whole journey from Xi'an to Beijing is the 10th The lane cannot be changed unless you have passed several high-speed sections (light regeneration section), such as Xi'an-Zhengzhou, Zhengzhou-Beijing, then you can have a chance to change lanes in Zhengzhou, and the cost of this lane replacement is for you. This behavior is dedicated to repairing a small road (laying fiber); when SDH encountered a similar situation, it repaired a large dispatch center in Zhengzhou, and all problems were solved. 3, easy to block (protection is imperfect): in the city's main roads or inter-provincial fast roads, in order to improve efficiency, the road design is considered to be different from ordinary roads, only a few few exits, other It is closed, and the consequence is that in the event of congestion or traffic accidents, passengers will be in trouble (business interruption); think about our city bus SDH, the driver will immediately take a small road when he sees the traffic jam ahead. There may be several passengers who can't get off at the destination (a small amount of business is interrupted), and most passengers can arrive smoothly. The reason is that there are a lot of available loops, plus flexible scheduling (the driver can decide) The Transportation Bureau (ITU-T) sees the problem and reforms from the following aspects: 1. Add monitoring equipment and necessary security administrators to all vehicles on the road----increasing OAM overhead 2. Adding a dispatching hub at the transportation hub node-----increasing service scheduling (inter-lane scheduling [optical layer scheduling] and cargo or passenger scheduling [electrical layer scheduling]) 3. Relying on the dispatching hub and adding a part of the lane or part of the vehicle on the road to provide perfect protection for all vehicles-----improving the protection mechanism SDH smiled: What reform is this, we have always done this, that is, the capacity is not big for you; WDM responded: My capacity is indeed much larger than you, but you have not done well in these areas; They shake hands and rejoice, complement each other, and a brand new system is born ------ OTN Overview of OTN: OTN is based on WDM and combines some advantages of SDH, such as rich OAM overhead, flexible service scheduling, and perfect protection. The scheduling of services by OTN is divided into: optical layer scheduling and electrical layer scheduling. Optical layer scheduling can be understood as the category of WDM; electrical layer scheduling can be understood as the scope of SDH So simply say: OTN=WDM+SDH However, the OTN's electrical layer scheduling work is somewhat different from SDH: Review the features of SDH: 1. Uniform departure frequency, 8000 times in 1 second, the system stipulates that it cannot be changed (following the PDH system); 2, through the development of larger tonnage vehicles to increase capacity, high-capacity vehicles are generally spliced ​​by four vehicles of a lower capacity level, so the structure of different capacity of the car is not the same; OTN electrical layer scheduling work features: 1. All vehicles are uniform in size, size and capacity. Dimensions: 4*4080; 2. Increase the frequency of departure according to demand advantage: 1. There is no need to continuously develop a larger capacity car and reduce development costs; 2. Unified structure for easy management; 3. Convenient transportation across regions (convenient exchange between different manufacturers); 4. In theory, the capacity can be increased indefinitely by increasing the frequency of the departure, and the implementation is simpler and clearer; Two flowers, one table, we have a detailed description of the development of the former Reds SDH in the rivers and lakes, now SDH is only equivalent to a master under the OTN head, then another red How is it developing now? In the past, Ethernet and ATM, like the Huashan faction, have a unique reputation in the martial arts with swordsmanship. They have a high reputation in the martial arts, but in the Huashan School, there are swords and swords that are dominated by swords. Mainly based on the sword Ethernet is like a sword, ATM is like a qizong Ethernet is known for its simplicity, and it is easy to get started with many disciples; ATM is too deep for its inner workings, and the people who practice it are embarrassing. In the final battle, Ethernet won a big victory, which is inconsistent with the plot in the novel, which is puzzling... Until one day, Ethernet is worrying about how to reinvigorate the martial art. At the same time, ATM is also depressed for the martial arts with such high enthusiasm. After two encounters and conversations, ATMs want to use Ethernet to improve their influence. Ethernet wants to take advantage of the inner workings of ATM to make it happen. After a few months of secret discussions, the two released a new martial arts secret - MPLS (Multi-Protocol Label Switching) The secret of the martial arts of the Ministry was later adapted into multiple versions, which is an important basis for other martial arts. This is a follow-up! Core comparison: ATM VPI VCI MPLS TUNNEL VC The momentum of Ethernet is getting bigger and bigger, and with the help of MPLS, there is gradually the ability to compete with SDH. Therefore, the initial integration of SDH and Ethernet has given birth to MSTP, but MSTP is still SDH because of equity issues. Leading, Ethernet, ATM can only be a supporting role, Ethernet is not happy, vowed to change it... In order to fight against the SDH camp, Ethernet has vigorously developed its own sphere of influence, and adopted the strategy of encircling the city in rural areas, first IP-based (business-side IP). IP can be used as SDH goods, transmitted via SDH, but the problem is: When SDH was originally developed, it had strict shape requirements for the goods. It must be a "block structure" and the size is also standard. Each seat is also made according to this requirement, so that the transportation efficiency is the highest; then the IP looks so strange ( There are more and more goods in the format. Even if MSTP is specially developed, MSTP is just a few special seats for IP and ATM on SDH vehicles. IP is still not very good! The reason is that IP is a powerful disciple under the Ethernet gate. Ethernet is a simple, unfettered, best-effort and other characteristics. Therefore, IP also has this feature, some small, some hypertrophy (IP frame length variable) If the IP in SDH/MSTP is small, the problem is not big. If the IP accounted for more than half, I am afraid that the cost of retrofitting the vehicle is too great. [MSTP: If the packet service is less than 50%, there is still a cost advantage]; But now the problem is that there are more and more IP goods. I have to set up a transportation company myself, and I have to say that I can no longer be controlled by SDH. At the same time, SDH thinks again, can I divide the car into two floors, one layer for The original business, a layer dedicated to IP reservations, so you can take care of it. Nowadays, it is really a period of contending for a hundred schools. Various new companies and new technologies have emerged. Let us first talk about the SDH camp. Since the previous MSTP was established, the equity distribution was uneven, and there were many legacy problems, which led to serious dissatisfaction with Ethernet now. Now SDH Group After the study, MSTP+ (also called HybridMSTP) was introduced, 50/50 equity allocation, vehicles became two-tier, two-tier management and scheduling, two scheduling systems (dual-core crossover); not a good compensation measure Besides, the Ethernet camp is free to use it. Now there are two big differences: A transportation company that believes that we have set up itself will not allow SDH customers (TDM business) to get on the bus. If we must come in, we must make a face-up - camouflage (simulation), and we don't have time guarantee (no time synchronization), we are pure Our Ethernet service, our company name is IP-RAN; A customer who thinks we should absorb some SDHs, SDH has been in business for so many years, and its customers are still a lot (and there are a lot of TDM business needs), and after that, it still needs to be changed - camouflage (simulation), and then our gang Activities, after the gang, then remove the disguise and restore it to its original appearance, the company named PTN Either way, camouflage-easy tolerance is always indispensable, and then PWE3 is easy to develop. There are two more factions in PTN: One is the product of MPLS, easy-to-capture PWE3 and MSTP -------- MPLS-TP faction; One fact is a combination of QinQ and MSTP products ------------------ PBT faction; For the MPLS-TP faction, there are many supporters, such as Huawei, ZTE, Bonfire, Alang, Ericsson, China Mobile and other heavyweight stars; For the PBT faction, the supporters only have the Nortel network, and the people are alone; So most of the PTN we see now is the MPLS-TP faction; With mutual learning, the difference between IP-RAN and PTN is getting smaller and smaller. The advantage of IP-RAN is three-layer connectionless service, but PTN can now be realized. Previously, PTN used to transmit SDH customer TDM service. Specially developed time and clock synchronization system called 1588 system, now using V2 version, V3 version is being tested, now IP-RAN has also learned, and also supports this system. It really should be the same sentence: the long-term must be combined for a long time! MSTP+ (Hybrid MSTP) can be regarded as a compromise solution from SDH to Ethernet, which is a last resort; IP-RAN and PTN are now in line with each other, the difference is not big, they can be seen as a comprehensive challenge to SDH, it seems that they are winning! Mbb Tabbing Ribbon Machine,Mbb Round Ribbon Machine,Solar Tinned Copper Ribbon Machine,New Energy Pv Ribbon Machine Jiangsu Lanhui Intelligent Equipment Technology Co., Ltd , https://www.lanhuisolar.com