VOIP Technology to Make Voice Calls

VOIP Technology to Make Voice Calls Faculty of Engineering, Architecture and Science Computer Networks Program Course Number CN8814 Course Title Network Mathematics and Simulations Semester/Year Summer 2015 Instructor Dr. Alagan Anpalagan Lab Assignment No Lab 2 Assignment Title QoS for VOIP Submission Date June 21,2015 Due Date June 21,2015 Student Name(s) Ishtiaq Ahmed Mohammad Shariful Ikram Student ID(s) 500666959 500543793 Signature(s) [emailprotected] [emailprotected] Table of Contents (Jump to) Objective Introduction Lab topology: Question 1: Question 2: Question 3: Question 4: Question 5: Question 6: Question 7: Conclusion   Objective In this lab, we have used VOIP technology to make voice calls. We have analyzed by implementing WFQ,CBWFQ and LLQ queuing techniques for improving the call quality. Introduction Quality of Service or QOS is used to increase the performance of voice application. End user can get voice call performance based on the QOS. It is a very critical implementation for voice over IP or VOIP based calls.QOS deals with reducing the delay and drop of packets compare with low priority traffic. If the delays are long, voice quality will be noisy and conversation will be very bad.QOS make sure the standard voice services by using existing resources. With this lab we have learned fragmentation with frame relay, traffic shaping techniques for improving the voice quality. In the first part of this lab, we will make voice call with FRF12 and analyze the voice quality. Then we will implement WFQ,CBWFQ and LLQ queuing techniques and will recognize suitable techniques for voice. In our network topology, router 7 is working as frame-relay switching. Router 1 and Router2 are connected with two telephones. Lab topology: Figure 1 Lab 2 topology We have configured VOIP peer between router 1 and router 2 with our lab instruction. 1. Configure voice over IP over Frame-Relay (FRF.12) and appropriate dial peers at Router 1 and Router 2 with the following information: Committed burst size (Bc) = 12000 bits Committed bit rate (CIR) = 64 kbps Frame relay fragment = 1500 bytes Voice codec: G.729 In this lab, we have used below information between router 1 and router 2: Following table shows initial configuration between router 1 and router 2: 2. Test your configuration by making a call between the two phones. Note the voice quality. With making a call between these phones, we have found voice quality is good. 3. Generate two ping traffic flows with 3000-byte packet size across PVC1. Make a voice call. Note that the voice quality deteriorates. To increase the traffic flow, we have changed the packets size 3000 byte by using extended ping command. After that we make call between our phones and gets distort voice because of delay and jitter. 4. Configure the frame-relay fragmentation and traffic shaping at the serial interfaces to improve the voice quality (the fragment delay is required to be less than 10 ms). To improve the voice quality, we have configured frame-relay fragmentation and traffic shaping between router 1 and router 2 serial interfaces: Question 1: How do you choose appropriate fragment size and committed burst size (Bc) to implement the frame-relay fragmentation and traffic shaping? Why the voice quality is improved after the configuration? In our lab requirements, fragment delay is less than 10 ms. So we have calculated the fragment size based on the following formula: Fragment size (Maximum): †¢ Fragment_size = (0.01 sec) * CIR = (0.01 sec) * 64 kbps = 80 bytes Parameters of Traffic Shapping: †¢ Burst size (Committed): Bc = 0.01 seconds * CIR = 640 bits After these configuration, we have made voice calls and have get better voice quality. Voice quality have improved because of smaller fragmentation. Question 2: Explain why FIFO queuing should not be used if fragmentation is configured. Fragmentation helps to break large data traffic into smaller data traffic. For this voice traffic gets priority and have served faster. In the FIFO technology, if any large data entered into the queue then in that time if any voice traffic comes, then it needs to be wait until large data traffic finishes. There is no way to prioritize the voice traffic in FIFO techniques. 5. Set IP precedence of the voice traffic to 5. Generate two ping traffic flows with 3000-byte packet size across PVC1. Make a voice call. Note the voice quality. In the type of service or TOS byte of Header, we have set IP precedence. IP precedence can identify class of services. Out of seven bits, left three digits are use in IP precedence. These values can be from zero to seven. Here larger number means higher priority. We have set IP precedence 5 and we make ping traffic with 3000 bytes in the PVC1.We have get voice quality good than the previous quality. Following table shows the configuration between router 1 and router 2: 6. Configure a RTP priority queue for voice traffic. Generate two ping traffic flows with 3000-byte packet size across PVC1. Make a voice call. Note the voice quality Following table shows the configuration between router 1 and router 2: We have generated two ping traffic between router 1 and router 2 with 3000 bytes packet size. After that we have test voice calls between our phones. We have get voice quality is good than previous. It has happened because 27 kbps bandwidth is reserve for voice packets and voice packets has no need to wait in the queue. Question 3: Determine the minimum bandwidth required for the RTP priority queue configuration. We have configured voice traffic with RTP priority queue. Our size of voice packet is 66 bytes. So the minimum requirement of bandwidth is 8*66/0.02 or 26,400 bps or 26.4 kbps. We have used G729 codec and voice payload size is 20 bytes. We set our lab bandwidth is 27 kbps. Question 4: Compare the voice qualities at Steps 4, 5, and 6, and explain the causes of quality differences. To compare voice qualities between steps 4,5, and 6, we have found voice quality is worst in step 4.It has happened for voice call and ping is ready at a time, all packets are transfer in the same queue. So lots of packet are drop because of more queuing delay. Voice traffic has high priority when we use IP precedence 5 in step 5.Our voice and data traffic still use the same bandwidth. Data traffic still transfer even voice traffic arrives. So ping traffic transfers and voice traffic waits. For this, voice quality is not good because there is no bandwidth reservation for voice traffic. In step 6,we have configured 27 kbps bandwidth in RTP priority queuing. This bandwidth is reserve for voice traffic. So voice packets always use this defined bandwidth and voice traffic has priority than ping traffic. So in this case, voice quality is better. 7. Configure three classes: VoIP, VoIP signaling, and default. Reserve bandwidth 25 kbps for VoIP class, and 8 kbps for VoIP signaling class, respectively. Do not assign priority queue to any class. Three different classes has been created in this case. They are assign with fix bandwidth. We have used access-lists for voice traffic classification. Following table shows configuration between router 1 and router 2. Question 5: Explain the differences and similarities between CBWFQ and WFQ. CBWFQ can utilize bandwidth effectively compare to WFQ. It is actually the extended version of WFQ. During the congestion period, CBWFQ can guarantee the minimum bandwidth. It will switch when it gets more bandwidth again. In the CBWFQ, we can define different classes and each different classes we can assign separate bandwidth. The differences and similarities between WFQ and CBWFQ are as follows: Similarities CBWFQ has default traffic class but if we do not define this class then CBWFQ and WFQ has no difference in queuing techniques. Differences Based on the user define classes ,CBWFQ can traffic queuing but WFQ cannot queue traffic. For the traffic flow, CBWFQ can make sure specific bandwidth for it but WFQ can not guarantee that. Network administrator can use CBWFQ more flexibly. They utilize this CBWFQ with different priorities for different types of traffic. Question 6: Based on the above configuration, what are the maximum and minimum bandwidths that are available for the default class? The maximum bandwidth that are available for the default class was 64 kbits/s Default class is use all available bandwidth like bandwidth = CIR = 64 kbit/s if there are no voice traffic Because if there is no voice or voice signaling traffic then the default class is use all available bandwidth (bandwidth = CIR = 64 kbit/s). The minimum bandwidth that are available for the default class is 31 kbit/s But if for voice or voice signaling flow, the reserving bandwidth will be 25 kbits/s and 8 kbit/s respectively. Other will be available for default class. So, minimum bandwidth available for default class is: 64kbps (25kbps + 8kbps) = 31 kbit/s We have generated two ping traffic through PVC1 and at the same time we do voice call. Our packet size is 3000 bytes. We have found same voice quality like step 6. 8. Establish a voice call between the two phones. At the same time, generate two ping traffic flows with 3000-byte packet size between the two routers. Note the voice quality. We have generated voice calls in our phones. At the same time between router 1 and router 2 we have generated 3000 byte ping traffic. We have found the acceptable voice quality. For voice traffic we have assign different class but there is no priority assign for this class. So, in the receiver end, both data and voice packets are receive similar way. So voice is not be clear because of delay introduce. 9. Configure a priority queue for VoIP class using LLQ. We have configured priority queue with LLQ. Following table shows the configuration: 10. Make a voice call between the two phones. Note the voice quality. After the configuration, we have make phone call with 3000 byte ping traffic in the same time. We found the improved voice quality. Question 7: Explain why the voice quality is improved after the priority configuration. Voice quality has improved for priority configuration. Previously we do not assign priority for different define classes of voice and voice signaling. So, voice quality is improved because of priority assigned. So for any ping traffic comes first it is served first. With the priority queue configuration, it has been resolved. So for any voice traffic arrival, it is use priority queue with allocated bandwidth. Conclusion In this lab, we have configured two routers and make phone call. We have observed the different call quality. Call quality depends on traffic flow. Traffic flows depends on different parameters like delay, jitter, loss of packets, etc. These hampers the quality of services. We have implemented three queuing discipline here like WFQ,CBWFQ,CBWFQ with LLQ. The objective of this lab is to analyze and improve the quality of voice service. We have found, the best voice quality when we have implemented different class for voice traffic and assign high priority value for voice traffic. Page | 1

Political Analysis on China Essay

China has been under the communist party rule for many decades. The communist party exercises absolute power over legislations and economic and cultural institutions. China rules and regulations are not so transparent or absolute. Due to lack of transparency and corruption the social network with the people from the communist party can help the business avoid red tape and bureaucracy. A political risk refers to government interference in the business affairs of foreign persons or companies doing business in a particular country.China is particularly hazardous with respect to political risk. In fact this has occurred in china in 1949. There are the risk of confiscation, risk of expropriation, and risk of contract repudiation.A unique form of political risk occurs in china, and this is the constant battle between the country’s central government and the provincial and local governments over applicable law, and observance or non-observance of it. This makes it difficult for companies operating in China to know exactly what the rules are. Other Political risk of China are as follows- 1) Political Effectiveness- Political effectiveness is actually not very effective in china as compared to other countries. Barely anyone bothers to call the police and they be easily bribed. Road laws are not enforced and thus there is a high rate of accidents in China with the way they drive. The government is even less confident than outside observers regarding their nation’s political stability. 2) Institutional Stability- Corruption still plays a huge role in China. They believe that profit comes first and mostly for personal reasons. At first it was only the Chinese Communist Party who took control in 1949. Later the other branches such as the Judicial Branch came into power in 1980. 3)Currency inconvertibility – The import and export business exchange currencies in either USD or RMB. Only certain worldwide currencies can be exchanged in China, other than that they use the RMB. 4) Honest Government- There are many cases known to justify corruption among government officials. Policies and laws are not solid or stable in China, therefore everything is negotiable. The CPI ratings of China are 3.5 this year. This looks bad compared to the United States and Canada. 106,000 officials were prosecuted for corruption in 2009 which was a 2.5% increase from 2008. With China’s growing economy, it will only get worse. Minimizing Political Risk- For minimizing political risk we should understand the importance of social networks and their relationship. It is a challenging process for a company to recruit the right people with the appropriate network to overcome these challenges. Legal System- For thousands of years, the Chinese legal system was based on Confucian ideology that emphasized ethics and relationships between the people and their leaders. China does not technically have an independent judiciary or a legal system that operates outside the influence of the ruling Chinese Communist Party. In fact, China’s lack of an independent judicial system. Legal and Regulatory Risk Regulatory risk in China is high. Although many sectors of China’s economy have become more market oriented, numerous restrictions and a massive bureaucracy still hinder full implementation of regulations and make the approval process unpredictable. China’s Judicial System- Using China’s judicial system also involves risk. Because of China’s WTO membership and growing pressure from foreign investors for greater transparency and rule of law, China increasingly recognizes overseas arbitration awards and rulings. It is, however, still risky for companies to rely solely on the PRC judicial system to protect their interests. Similarly, China’s accession to the WTO has brought with it the inclusion of international business laws and patent rights amendments, but even today it is common to see technology being stolen either by the employees of the outsourced firm in China or by a Chinese competitor in the country. Protection from foreign Currency Earning Enterprises- The cost of doing business in China is frequently higher than companies expect. These issues, coupled with a recent rise in policies aimed at protecting domestic companies from foreign competition— especially in engineering and construction, legal services, and banking—create risks and obstacles that few foreign companies are aware of until too late. Minimizing Legal Risk- Hence western companies that plan to outsource manufacturing to China should be aware of these legal challenges. One way of preventing these issues is to have a strong network with the locals or to make sure that sensitive technology is not outsourced to China. Cultural Challenges China has evidenced thousands of years of history, culture and traditions. The way Chinese people behave today is the result of its historical transformations, which is very different from the transformations witnessed by western societies. Hence the modern day Chinese culture is very different from the cultures of the west. The cultural aspects of the Chinese are immensely reflected in the business world, for example, A CEO in the western world is normally looked upon as a consensus builder or as an individual who debates and discusses strategies with their employees and then executes the strategy, whereas in China the leader is looked upon as the sole decider and executor of strategies. There is a strict hierarchy in the Chinese business culture, which is very different from the business culture of some of the west countries. So to run a successful wholly owned outsourcing unit in China, the western businessmen need to understand and overcome these cultural chal lenges. Challenges in Scale and Demographics China is a vast country with a massive population, Western businesses are often at awe about China and think that the 1.3 billion people could become a large customer base, but in reality China is a complex market. 850 million people in China live in the impoverished countryside; their life is harsh, uncertain and poor.536 million people live in the urban areas out of which 247 million people are considered middle class and have an expendable income. The middle class earns over $5000 per head over the period of a year, but one must also consider the fact that the Chinese are the largest savers in the world unlike some western countries such as the US where the consumers have massive spending power and a culture that promotes spending. Hence for a western company to succeed they need to understand these Demographic differences. Challenges related to market behaviour The Chinese market is unique in many aspects, many western companies have tried to sell their product as-is in the Chinese market and failed miserably, and these are not some small unknown brands but large mega brands that have been successful for many decades and different markets. To be recognized as a brand in China, one need to market and advertise the Chinese way, marketing and branding in China should carry a strong Chinese Cultural overtone to be successful in the mainland. Successful western companies such as Google and eBay have failed to become market leaders in China. The lesson learnt from the failure of these companies is that they â€Å"did not understand the localization factor† Therefore for the long run, western companies should â€Å"Think Chinese but act western† and sell the right product at the right price to be successful in the Chinese market. Economic instability & Trade policy Challenges China is the world’s second largest economy and is among the fastest growing economies of the world. When western companies move to China they have to consider the economic stability of the country and prepare themselves for the various risks due to changes in fiscal policy, monetary policy, trade policy and other macro economic factors. China’s economy is mostly dependent on exports from the manufacturing industry and foreign economists suggest that the Yuan is undervalued by as much as 40%. Hence a Change in the Yuan can impact the profitability of the western business. Due to high economic growth there has been a strong demand for semi and highly skilled labour all over China. The labour costs have steadily increased over the last 5 years and the government has increased the minimum wage level. This will impact operating costs in China and hence a western company planning to operate in China will have to factor in this r isk. In summary western enterprises need to be aware of macroeconomic risks before they start their operations in China or face the possibility of failure.

Ethics Morality and Vincible Ignorance - 1966 Words

ETHICS Greek ; ethos – custom, character Ethikos- moral, showing moral character, moral judgment The science of the MORALITY OF HUMAN ACTS Morality is the goodness or badness of an act Moral(good), immoral(bad) and amoral ( indifferent or neutral, neither good nor bad) HUMAN ACT-----------------------------------------------------------------ACT OF MAN - Action done with knowledge and consent -no knowledge and consent - Action of man as man and as rational -involuntary 3 ELEMENTS OF HUMAN ACT: - Acts of sensation 1. KNOWLEDGE –with awareness 2. FREE WILL – with choice 3. VOLUNTARINESS- with willingness MODIFIERS OF HUMAN ACTS PRINCIPLE: â€Å"The greater the knowledge and freedom, the greater the voluntariness; and the greater the†¦show more content†¦Being left alone in a strange place, being asked to speak before a group of people 2) Act out of fear or because of fear - fear here becomes a positive force compelling a person to act without careful deliberation - fear modifies the freedom of doing, inducing the person to act in a certain predetermined manner, even without his full consent Ex. A child – studies/reads his books – out of fear of his mother A man – stops smoking – fear of contracting cancer PRINCIPLES: 1) Acts done with fear are voluntary - acting inspite of his fear and is in full control of himself 2) Acts done out of fear are simply voluntary although conditionally involuntary - simply voluntary = person remains in control of his faculties - conditionally involuntary = if it were not for the presence of something feared, the per son would not act or would act in another way - Intimidating or threatening as person with horror is an unjust act - Legally speaking, acts done out of fear – invalid acts Ex. Contract – made out of fear – voidable – later be annulled 3) Acts done because of intense fear or panic are involuntary - panic – obscures the mind – in this mental state, the person is not expected to think sensibly D) HABIT - permanent inclinations to act in a certain way - lasting readiness and facility born of

Biography of Manco Inca (1516-1544) Ruler of the Inca Empire

Manco Inca (1516-1544) was an Inca Prince and later a puppet ruler of the Inca Empire under the Spanish. Although he initially worked with the Spanish who had put him on the throne of the Inca Empire, he later came to realize that the Spanish would usurp the Empire and fought against them. He spent his last few years in open rebellion against the Spanish. He was eventually treacherously murdered by Spaniards to whom he had given sanctuary. Manco Inca and the Civil War Manco was one of the many sons of Huayna Capac, ruler of the Inca Empire. Huayna Capac died in 1527 and a war of succession broke out among two of his sons, Atahualpa and Huascar. Atahualpas base of power was in the north, in and around the city of Quito, while Huascar held Cuzco and the south. Manco was one of several princes who supported Huascars claim. In 1532, Atahualpa defeated Huascar. Just then, however, a group of Spaniards arrived under Francisco Pizarro: they took Atahualpa captive and threw the Inca Empire into chaos. Like many in Cuzco who had supported Huascar, Manco initially saw the Spaniards as saviors. Mancos Rise to Power The Spanish executed Atahualpa and found they needed a puppet Inca to rule the Empire while they plundered it. They settled on one of Huayna Capacs other sons, Tupac Huallpa. He died of smallpox shortly after his coronation, however, so the Spanish selected Manco, who had already proven himself loyal by fighting alongside the Spanish against rebellious natives from Quito. He was formally crowned Inca (the word Inca is similar in meaning to king or emperor) in December of 1533. At first, he was an eager, compliant ally of the Spanish: he was happy that they had selected him for the throne: as his mother had been lesser nobility, he most likely never would have been Inca otherwise. He helped the Spanish put down rebellions and even organized a traditional Inca hunt for the Pizarros. The Inca Empire Under Manco Manco may have been Inca, but his empire was falling apart. Packs of Spanish rode across the land, looting and murdering. The natives in the northern half of the empire, still loyal to the murdered Atahualpa, were in open revolt. Regional chiefs, who had seen the Inca royal family fail to repel the hated invaders, took on more autonomy. In Cuzco, Spaniards openly disrespected Manco: his home was robbed on more than one occasion and the Pizarro brothers, who were the de facto rulers of Peru, did nothing about it. Manco was allowed to preside over traditional religious rituals, but Spanish priests were putting pressure on him to abandon them. The Empire was slowly but surely deteriorating. Abuses of Manco The Spanish were openly contemptuous of Manco. His house was robbed, he was repeatedly threatened to produce more gold and silver, and the Spanish even spat upon him occasionally. The worst abuses came when Francisco Pizarro went to found the city of Lima on the coast and left his brothers Juan and Gonzalo Pizarro in charge in Cuzco. Both brothers tormented Manco, but Gonzalo was the worst. He demanded an Inca princess for a bride and decided that only Cura Ocllo, who was the wife/sister of Manco, would do. He demanded her for himself, causing a great scandal among what was left of the Inca ruling class. Manco deceived Gonzalo for a while with a double, but it didnt last and eventually, Gonzalo stole Mancos wife. Manco, Almagro and the Pizarros Around this time (1534) a serious disagreement broke out among the Spanish conquistadors. The conquest of Peru had originally been undertaken by a partnership between two veteran conquistadors, Francisco Pizarro and Diego de Almagro. The Pizarros tried to cheat Almagro, who was rightfully irked. Later, the Spanish crown divided the Inca Empire between the two men, but the wording of the order was vague, leading both men to believe that Cuzco belonged to them. Almagro was temporarily placated by allowing him to conquer Chile, where it was hoped he would find enough loot to satisfy him. Manco, perhaps because the Pizarro brothers had treated him so badly, supported Almagro. Mancos Escape By late 1535, Manco had seen enough. It was obvious to him that he was ruler in name only and that the Spanish did not intend to ever give back the rule of Peru to the natives. The Spanish were plundering his land and enslaving and raping his people. Manco knew that the longer he waited, the harder it would be to remove the hated Spanish. He tried to escape in October of 1535, but he was captured and put into chains. He regained the confidence of the Spanish and came up with a clever plan to escape: he told the Spanish that as Inca he needed to preside over a religious ceremony in the Yucay Valley. When the Spanish hesitated, he promised to bring back a life-sized golden statue of his father that he knew was hidden there. The promise of gold worked to perfection, as Manco had known it would. Manco escaped on April 18, 1535, and launched his rebellion. Mancos First Rebellion Once free, Manco sent out a call to arms for all his generals and local chieftains. They responded by sending massive levies of warriors: before long, Manco had an army of at least 100,000 warriors. Manco made a tactical mistake, waiting for all of the warriors to arrive before marching on Cuzco: the extra time given to the Spanish to make their defenses proved crucial. Manco marched on Cuzco in early 1536. There were only about 190 Spaniards in the city, although they had many native auxiliaries. On May 6, 1536, Manco launched a massive attack on the city and nearly captured it: parts of it were burned. The Spanish counterattacked and captured the fortress of Sachsaywaman, which was much more defensible. For a while, there was a stalemate of sorts, until the return in early 1537 of the Diego de Almagro expedition. Manco attacked Almagro and failed: his army dispersed. Manco, Almagro and the Pizarros Manco was driven off, but saved by the fact that Diego de Almagro and the Pizarro brothers began fighting among themselves. Almagros expedition had found nothing but hostile natives and harsh conditions in Chile and had returned to take their share of the loot from Peru. Almagro seized the weakened Cuzco, capturing Hernando and Gonzalo Pizarro. Manco, meanwhile, retreated to the town of Vitcos in the remote Vilcabamba Valley. An expedition under Rodrigo Orgà ³Ãƒ ±ez penetrated deep into the valley but Manco escaped. Meanwhile, he watched as the Pizarro and Almargo factions went to war: the Pizarros prevailed at the battle of Salinas in April of 1538. The civil wars among the Spanish had weakened them and Manco was ready to strike again. Mancos Second Rebellion In late 1537 Manco rose up in rebellion once again. Instead of raising a massive army and leading it himself against the hated invaders, he tried a different tactic. The Spaniards were spread out all over Peru in isolated garrisons and expedition: Manco organized local tribes and revolts aimed at picking these groups off. This strategy was partly successful: a handful of Spanish expeditions were wiped out, and travel became extremely unsafe. Manco himself led an attack on the Spanish at Jauja, but was rebuffed. The Spanish responded by sending out expeditions specifically to track him down: by 1541 Manco was on the run again and retreated again to Vilcabamba. The Death of Manco Inca Once again, Manco waited things out in Vilcabamba. In 1541, all of Peru was shocked when Francisco Pizarro was murdered in Lima by assassins loyal to the son of Diego de Almagro and the civil wars flared up again. Manco again decided to let his enemies slaughter one another: once again, the Almagrist faction was defeated. Manco did give sanctuary to seven Spaniards who had fought for Almagro and feared for their lives: he put these men to work teaching his soldiers how to ride horses and use European weapons. These men betrayed and murdered him sometime in mid-1544, hoping to gain a pardon by doing so. Instead, they were tracked down and killed by Mancos forces. Legacy of Manco Inca Manco Inca was a good man in a tough spot: he owed his position of privilege to the Spanish, but soon came to see that his allies would destroy the Peru he knew. He therefore put the good of his people first and started a rebellion which lasted almost ten years. During this time, his men fought the Spanish tooth and nail all over Peru: had he re-taken Cuzco swiftly in 1536, the course of Andean history might have altered dramatically. Mancos revolt is a credit to his wisdom in seeing that the Spanish would not rest until every ounce of gold and silver was taken from his people. The blatant disrespect showed to him by Juan and Gonzalo Pizarro, among many others, certainly had much to do with it, too. Had the Spaniards treated him with dignity and respect, he might have played the part of puppet emperor longer. Unfortunately for the Andean natives, Mancos revolt represented the last, best hope for the removal of the hated Spanish. After Manco, there was a short succession of Inca rulers, both Spanish puppets and independent ones in Vilcabamba. Tà ºpac Amaru was killed by the Spanish in 1572, the last of the Inca. Some of these men fought the Spanish, but none of them had the resources or skills that Manco did. When Manco died, any realistic hope for a return to native rule in the Andes died with him. Manco was a skilled guerrilla leader: he learned during his first rebellion that large armies are not always best: during his second rebellion, he relied on smaller forces to pick off isolated groups of Spaniards and had much more success. When he was killed, he was training his men in the use of European weapons, adapting to the changing times of warfare. Sources: Burkholder, Mark and Lyman L. Johnson. Colonial Latin America. Fourth Edition. New York: Oxford University Press, 2001. Hemming, John. The Conquest of the Inca London: Pan Books, 2004 (original 1970). Patterson, Thomas C. The Inca Empire: The Formation and Disintegration of a Pre-Capitalist State.New York: Berg Publishers, 1991.