Applicable to public universities under the Central Government, submitted to the Government for consideration and comments before promulgation for implementation.
- Heads of public universities, based on the above regulations, have the right to autonomy and take responsibility for developing and deciding on specific tuition fee collection plans applicable to their students.
Third , with the above solution, for the group of autonomous and self-responsible universities, there are regulations allowing the development and decision of tuition collection plans applicable to their units in accordance with the principles of determining tuition collection levels prescribed by the State.
Fourth, the tuition fee collection plan of universities must be submitted to the financial authority for review and comments before being issued for implementation; once the decision is made to issue for implementation, it must be publicly announced.
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Perfecting the interest rate management mechanism of the State Bank of Vietnam in the conditions of a market economy - 30 -
Current Status of Financial Management Mechanism of Financial Resources Mobilized Outside the State Budget for Public Universities -
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![Qos Assurance Methods for Multimedia Communications
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low. The EF PHB requires a sufficiently large number of output ports to provide low delay, low loss, and low jitter.
EF PHBs can be implemented if the output ports bandwidth is sufficiently large, combined with small buffer sizes and other network resources dedicated to EF packets, to allow the routers service rate for EF packets on an output port to exceed the arrival rate λ of packets at that port.
This means that packets with PHB EF are considered with a pre-allocated amount of output bandwidth and a priority that ensures minimum loss, minimum delay and minimum jitter before being put into operation.
PHB EF is suitable for channel simulation, leased line simulation, and real-time services such as voice, video without compromising on high loss, delay and jitter values.
Figure 2.10 Example of EF installation
Figure 2.10 shows an example of an EF PHB implementation. This is a simple priority queue scheduling technique. At the edges of the DS domain, EF packet traffic is prioritized according to the values agreed upon by the SLA. The EF queue in the figure needs to output packets at a rate higher than the packet arrival rate λ. To provide an EF PHB over an end-to-end DS domain, bandwidth at the output ports of the core routers needs to be allocated in advance to ensure the requirement μ > λ. This can be done by a pre-configured provisioning process. In the figure, EF packets are placed in the priority queue (the upper queue). With such a length, the queue can operate with μ > λ.
Since EF was primarily used for real-time services such as voice and video, and since real-time services use UDP instead of TCP, RED is generally
not suitable for EF queues because applications using UDP will not respond to random packet drop and RED will strip unnecessary packets.
2.2.4.2 Assured Forwarding (AF) PHB
PHB AF is defined by RFC 2597. The purpose of PHB AF is to deliver packets reliably and therefore delay and jitter are considered less important than packet loss. PHB AF is suitable for non-real-time services such as applications using TCP. PHB AF first defines four classes: AF1, AF2, AF3, AF4. For each of these AF classes, packets are then classified into three subclasses with three distinct priority levels.
Table 2.8 shows the four AF classes and 12 AF subclasses and the DSCP values for the 12 AF subclasses defined by RFC 2597. RFC 2597 also allows for more than three separate priority levels to be added for internal use. However, these separate priority levels will only have internal significance.
PHB Class
PHB Subclass
Package type
DSCP
AF4
AF41
Short
100010
AF42
Medium
100100
AF43
High
100110
AF3
AF31
Short
011010
AF32
Medium
011100
AF33
High
011110
AF2
AF21
Short
010010
AF22
Medium
010100
AF23
High
010110
AF1
AF11
Short
001010
AF12
Medium
001100
AF13
High
001110
Table 2.8 AF DSCPs
The AF PHB ensures that packets are forwarded with a high probability of delivery to the destination within the bounds of the rate agreed upon in an SLA. If AF traffic at an ingress port exceeds the pre-priority rate, which is considered non-compliant or “out of profile”, the excess packets will not be delivered to the destination with the same probability as the packets belonging to the defined traffic or “in profile” packets. When there is network congestion, the out of profile packets are dropped before the in profile packets are dropped.
When service levels are defined using AF classes, different quantity and quality between AF classes can be realized by allocating different amounts of bandwidth and buffer space to the four AF classes. Unlike
EF, most AF traffic is non-real-time traffic using TCP, and the RED queue management strategy is an AQM (Adaptive Queue Management) strategy suitable for use in AF PHBs. The four AF PHB layers can be implemented as four separate queues. The output port bandwidth is divided into four AF queues. For each AF queue, packets are marked with three “colors” corresponding to three separate priority levels.
In addition to the 32 DSCP 1 groups defined in Table 2.8, 21 DSCPs have been standardized as follows: one for PHB EF, 12 for PHB AF, and 8 for CSCP. There are 11 DSCP 1 groups still available for other standards.
2.2.5.Example of Differentiated Services
We will look at an example of the Differentiated Service model and mechanism of operation. The architecture of Differentiated Service consists of two basic sets of functions:
Edge functions: include packet classification and traffic conditioning. At the inbound edge of the network, incoming packets are marked. In particular, the DS field in the packet header is set to a certain value. For example, in Figure 2.12, packets sent from H1 to H3 are marked at R1, while packets from H2 to H4 are marked at R2. The labels on the received packets identify the service class to which they belong. Different traffic classes receive different services in the core network. The RFC definition uses the term behavior aggregate rather than the term traffic class. After being marked, a packet can be forwarded immediately into the network, delayed for a period of time before being forwarded, or dropped. We will see that there are many factors that affect how a packet is marked, and whether it is forwarded immediately, delayed, or dropped.
Figure 2.12 DiffServ Example
Core functionality: When a DS-marked packet arrives at a Diffservcapable router, the packet is forwarded to the next router based on
Per-hop behavior is associated with packet classes. Per-hop behavior affects router buffers and the bandwidth shared between competing classes. An important principle of the Differentiated Service architecture is that a routers per-hop behavior is based only on the packets marking or the class to which it belongs. Therefore, if packets sent from H1 to H3 as shown in the figure receive the same marking as packets from H2 to H4, then the network routers treat the packets exactly the same, regardless of whether the packet originated from H1 or H2. For example, R3 does not distinguish between packets from h1 and H2 when forwarding packets to R4. Therefore, the Differentiated Service architecture avoids the need to maintain router state about separate source-destination pairs, which is important for network scalability.
Chapter Conclusion
Chapter 2 has presented and clarified two main models of deploying and installing quality of service in IP networks. While the traditional best-effort model has many disadvantages, later models such as IntServ and DiffServ have partly solved the problems that best-effort could not solve. IntServ follows the direction of ensuring quality of service for each separate flow, it is built similar to the circuit switching model with the use of the RSVP resource reservation protocol. IntSer is suitable for services that require fixed bandwidth that is not shared such as VoIP services, multicast TV services. However, IntSer has disadvantages such as using a lot of network resources, low scalability and lack of flexibility. DiffServ was born with the idea of solving the disadvantages of the IntServ model.
DiffServ follows the direction of ensuring quality based on the principle of hop-by-hop behavior based on the priority of marked packets. The policy for different types of traffic is decided by the administrator and can be changed according to reality, so it is very flexible. DiffServ makes better use of network resources, avoiding idle bandwidth and processing capacity on routers. In addition, the DifServ model can be deployed on many independent domains, so the ability to expand the network becomes easy.
Chapter 3: METHODS TO ENSURE QoS FOR MULTIMEDIA COMMUNICATIONS
In packet-switched networks, different packet flows often have to share the transmission medium all the way to the destination station. To ensure the fair and efficient allocation of bandwidth to flows, appropriate serving mechanisms are required at network nodes, especially at gateways or routers, where many different data flows often pass through. The scheduler is responsible for serving packets of the selected flow and deciding which packet will be served next. Here, a flow is understood as a set of packets belonging to the same priority class, or originating from the same source, or having the same source and destination addresses, etc.
In normal state when there is no congestion, packets will be sent as soon as they are delivered. In case of congestion, if QoS assurance methods are not applied, prolonged congestion can cause packet drops, affecting service quality. In some cases, congestion is prolonged and widespread in the network, which can easily lead to the network being frozen, or many packets being dropped, seriously affecting service quality.
Therefore, in this chapter, in sections 3.2 and 3.3, we introduce some typical network traffic load monitoring techniques to predict and prevent congestion before it occurs through the measure of dropping (removing) packets early when there are signs of impending congestion.
3.1. DropTail method
DropTail is a simple, traditional queue management method based on FIFO mechanism. All incoming packets are placed in the queue, when the queue is full, the later packets are dropped.
Due to its simplicity and ease of implementation, DropTail has been used for many years on Internet router systems. However, this algorithm has the following disadvantages:
− Cannot avoid the phenomenon of “Lock out”: Occurs when 1 or several traffic streams monopolize the queue, making packets of other connections unable to pass through the router. This phenomenon greatly affects reliable transmission protocols such as TCP. According to the anti-congestion algorithm, when locked out, the TCP connection stream will reduce the window size and reduce the packet transmission speed exponentially.
− Can cause Global Synchronization: This is the result of a severe “Lock out” phenomenon. Some neighboring routers have their queues monopolized by a number of connections, causing a series of other TCP connections to be unable to pass through and simultaneously reducing the transmission speed. After those monopolized connections are temporarily suspended,
Once the queue is cleared, it takes a considerable amount of time for TCP connections to return to their original speed.
− Full Queue phenomenon: Data transmitted on the Internet often has an explosion, packets arriving at the router are often in clusters rather than in turn. Therefore, the operating mechanism of DropTail makes the queue easily full for a long period of time, leading to the average delay time of large packets. To avoid this phenomenon, with DropTail, the only way is to increase the routers buffer, this method is very expensive and ineffective.
− No QoS guarantee: With the DropTail mechanism, there is no way to prioritize important packets to be transmitted through the router earlier when all are in the queue. Meanwhile, with multimedia communication, ensuring connection and stable speed is extremely important and the DropTail algorithm cannot satisfy.
The problem of choosing the buffer size of the routers in the network is to “absorb” short bursts of traffic without causing too much queuing delay. This is necessary in bursty data transmission. The queue size determines the size of the packet bursts (traffic spikes) that we want to be able to transmit without being dropped at the routers.
In IP-based application networks, packet dropping is an important mechanism for indirectly reporting congestion to end stations. A solution that prevents router queues from filling up while reducing the packet drop rate is called dynamic queue management.
3.2. Random elimination method – RED
3.2.1 Overview
RED (Random Early Detection of congestion; Random Early Drop) is one of the first AQM algorithms proposed in 1993 by Sally Floyd and Van Jacobson, two scientists at the Lawrence Berkeley Laboratory of the University of California, USA. Due to its outstanding advantages compared to previous queue management algorithms, RED has been widely installed and deployed on the Internet.
The most fundamental point of their work is that the most effective place to detect congestion and react to it is at the gateway or router.
Source entities (senders) can also do this by estimating end-to-end delay, throughput variability, or the rate of packet retransmissions due to drop. However, the sender and receiver view of a particular connection cannot tell which gateways on the network are congested, and cannot distinguish between propagation delay and queuing delay. Only the gateway has a true view of the state of the queue, the link share of the connections passing through it at any given time, and the quality of service requirements of the
traffic flows. The RED gateway monitors the average queue length, which detects early signs of impending congestion (average queue length exceeding a predetermined threshold) and reacts appropriately in one of two ways:
− Drop incoming packets with a certain probability, to indirectly inform the source of congestion, the source needs to reduce the transmission rate to keep the queue from filling up, maintaining the ability to absorb incoming traffic spikes.
− Mark “congestion” with a certain probability in the ECN field in the header of TCP packets to notify the source (the receiving entity will copy this bit into the acknowledgement packet).
Figure 3. 1 RED algorithm
The main goal of RED is to avoid congestion by keeping the average queue size within a sufficiently small and stable region, which also means keeping the queuing delay sufficiently small and stable. Achieving this goal also helps: avoid global synchronization, not resist bursty traffic flows (i.e. flows with low average throughput but high volatility), and maintain an upper bound on the average queue size even in the absence of cooperation from transport layer protocols.
To achieve the above goals, RED gateways must do the following:
− The first is to detect congestion early and react appropriately to keep the average queue size small enough to keep the network operating in the low latency, high throughput region, while still allowing the queue size to fluctuate within a certain range to absorb short-term fluctuations. As discussed above, the gateway is the most appropriate place to detect congestion and is also the most appropriate place to decide which specific connection to report congestion to.
− The second thing is to notify the source of congestion. This is done by marking and notifying the source to reduce traffic. Normally the RED gateway will randomly drop packets. However, if congestion
If congestion is detected before the queue is full, it should be combined with packet marking to signal congestion. The RED gateway has two options: drop or mark; where marking is done by marking the ECN field of the packet with a certain probability, to signal the source to reduce the traffic entering the network.
− An important goal that RED gateways need to achieve is to avoid global synchronization and not to resist traffic flows that have a sudden characteristic. Global synchronization occurs when all connections simultaneously reduce their transmission window size, leading to a severe drop in throughput at the same time. On the other hand, Drop Tail or Random Drop strategies are very sensitive to sudden flows; that is, the gateway queue will often overflow when packets from these flows arrive. To avoid these two phenomena, gateways can use special algorithms to detect congestion and decide which connections will be notified of congestion at the gateway. The RED gateway randomly selects incoming packets to mark; with this method, the probability of marking a packet from a particular connection is proportional to the connections shared bandwidth at the gateway.
− Another goal is to control the average queue size even without cooperation from the source entities. This can be done by dropping packets when the average size exceeds an upper threshold (instead of marking it). This approach is necessary in cases where most connections have transmission times that are less than the round-trip time, or where the source entities are not able to reduce traffic in response to marking or dropping packets (such as UDP flows).
3.2.2 Algorithm
This section describes the algorithm for RED gateways. RED gateways calculate the average queue size using a low-pass filter. This average queue size is compared with two thresholds: minth and maxth. When the average queue size is less than the lower threshold, no incoming packets are marked or dropped; when the average queue size is greater than the upper threshold, all incoming packets are dropped. When the average queue size is between minth and maxth, each incoming packet is marked or dropped with a probability pa, where pa is a function of the average queue size avg; the probability of marking or dropping a packet for a particular connection is proportional to the bandwidth share of that connection at the gateway. The general algorithm for a RED gateway is described as follows: [5]
For each packet arrival
Caculate the average queue size avg If minth ≤ avg < maxth
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Qos Assurance Methods for Multimedia Communications
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low. The EF PHB requires a sufficiently large number of output ports to provide low delay, low loss, and low jitter.
EF PHBs can be implemented if the output port's bandwidth is sufficiently large, combined with small buffer sizes and other network resources dedicated to EF packets, to allow the router's service rate for EF packets on an output port to exceed the arrival rate λ of packets at that port.
This means that packets with PHB EF are considered with a pre-allocated amount of output bandwidth and a priority that ensures minimum loss, minimum delay and minimum jitter before being put into operation.
PHB EF is suitable for channel simulation, leased line simulation, and real-time services such as voice, video without compromising on high loss, delay and jitter values.
Figure 2.10 Example of EF installation
Figure 2.10 shows an example of an EF PHB implementation. This is a simple priority queue scheduling technique. At the edges of the DS domain, EF packet traffic is prioritized according to the values agreed upon by the SLA. The EF queue in the figure needs to output packets at a rate higher than the packet arrival rate λ. To provide an EF PHB over an end-to-end DS domain, bandwidth at the output ports of the core routers needs to be allocated in advance to ensure the requirement μ > λ. This can be done by a pre-configured provisioning process. In the figure, EF packets are placed in the priority queue (the upper queue). With such a length, the queue can operate with μ > λ.
Since EF was primarily used for real-time services such as voice and video, and since real-time services use UDP instead of TCP, RED is generally
not suitable for EF queues because applications using UDP will not respond to random packet drop and RED will strip unnecessary packets.
2.2.4.2 Assured Forwarding (AF) PHB
PHB AF is defined by RFC 2597. The purpose of PHB AF is to deliver packets reliably and therefore delay and jitter are considered less important than packet loss. PHB AF is suitable for non-real-time services such as applications using TCP. PHB AF first defines four classes: AF1, AF2, AF3, AF4. For each of these AF classes, packets are then classified into three subclasses with three distinct priority levels.
Table 2.8 shows the four AF classes and 12 AF subclasses and the DSCP values for the 12 AF subclasses defined by RFC 2597. RFC 2597 also allows for more than three separate priority levels to be added for internal use. However, these separate priority levels will only have internal significance.
PHB Class
PHB Subclass
Package type
DSCP
AF4
AF41
Short
100010
AF42
Medium
100100
AF43
High
100110
AF3
AF31
Short
011010
AF32
Medium
011100
AF33
High
011110
AF2
AF21
Short
010010
AF22
Medium
010100
AF23
High
010110
AF1
AF11
Short
001010
AF12
Medium
001100
AF13
High
001110
Table 2.8 AF DSCPs
The AF PHB ensures that packets are forwarded with a high probability of delivery to the destination within the bounds of the rate agreed upon in an SLA. If AF traffic at an ingress port exceeds the pre-priority rate, which is considered non-compliant or “out of profile”, the excess packets will not be delivered to the destination with the same probability as the packets belonging to the defined traffic or “in profile” packets. When there is network congestion, the out of profile packets are dropped before the in profile packets are dropped.
When service levels are defined using AF classes, different quantity and quality between AF classes can be realized by allocating different amounts of bandwidth and buffer space to the four AF classes. Unlike
EF, most AF traffic is non-real-time traffic using TCP, and the RED queue management strategy is an AQM (Adaptive Queue Management) strategy suitable for use in AF PHBs. The four AF PHB layers can be implemented as four separate queues. The output port bandwidth is divided into four AF queues. For each AF queue, packets are marked with three “colors” corresponding to three separate priority levels.
In addition to the 32 DSCP 1 groups defined in Table 2.8, 21 DSCPs have been standardized as follows: one for PHB EF, 12 for PHB AF, and 8 for CSCP. There are 11 DSCP 1 groups still available for other standards.
2.2.5.Example of Differentiated Services
We will look at an example of the Differentiated Service model and mechanism of operation. The architecture of Differentiated Service consists of two basic sets of functions:
Edge functions: include packet classification and traffic conditioning. At the inbound edge of the network, incoming packets are marked. In particular, the DS field in the packet header is set to a certain value. For example, in Figure 2.12, packets sent from H1 to H3 are marked at R1, while packets from H2 to H4 are marked at R2. The labels on the received packets identify the service class to which they belong. Different traffic classes receive different services in the core network. The RFC definition uses the term behavior aggregate rather than the term traffic class. After being marked, a packet can be forwarded immediately into the network, delayed for a period of time before being forwarded, or dropped. We will see that there are many factors that affect how a packet is marked, and whether it is forwarded immediately, delayed, or dropped.
Figure 2.12 DiffServ Example
Core functionality: When a DS-marked packet arrives at a Diffservcapable router, the packet is forwarded to the next router based on
Per-hop behavior is associated with packet classes. Per-hop behavior affects router buffers and the bandwidth shared between competing classes. An important principle of the Differentiated Service architecture is that a router's per-hop behavior is based only on the packet's marking or the class to which it belongs. Therefore, if packets sent from H1 to H3 as shown in the figure receive the same marking as packets from H2 to H4, then the network routers treat the packets exactly the same, regardless of whether the packet originated from H1 or H2. For example, R3 does not distinguish between packets from h1 and H2 when forwarding packets to R4. Therefore, the Differentiated Service architecture avoids the need to maintain router state about separate source-destination pairs, which is important for network scalability.
Chapter Conclusion
Chapter 2 has presented and clarified two main models of deploying and installing quality of service in IP networks. While the traditional best-effort model has many disadvantages, later models such as IntServ and DiffServ have partly solved the problems that best-effort could not solve. IntServ follows the direction of ensuring quality of service for each separate flow, it is built similar to the circuit switching model with the use of the RSVP resource reservation protocol. IntSer is suitable for services that require fixed bandwidth that is not shared such as VoIP services, multicast TV services. However, IntSer has disadvantages such as using a lot of network resources, low scalability and lack of flexibility. DiffServ was born with the idea of solving the disadvantages of the IntServ model.
DiffServ follows the direction of ensuring quality based on the principle of hop-by-hop behavior based on the priority of marked packets. The policy for different types of traffic is decided by the administrator and can be changed according to reality, so it is very flexible. DiffServ makes better use of network resources, avoiding idle bandwidth and processing capacity on routers. In addition, the DifServ model can be deployed on many independent domains, so the ability to expand the network becomes easy.
Chapter 3: METHODS TO ENSURE QoS FOR MULTIMEDIA COMMUNICATIONS
In packet-switched networks, different packet flows often have to share the transmission medium all the way to the destination station. To ensure the fair and efficient allocation of bandwidth to flows, appropriate serving mechanisms are required at network nodes, especially at gateways or routers, where many different data flows often pass through. The scheduler is responsible for serving packets of the selected flow and deciding which packet will be served next. Here, a flow is understood as a set of packets belonging to the same priority class, or originating from the same source, or having the same source and destination addresses, etc.
In normal state when there is no congestion, packets will be sent as soon as they are delivered. In case of congestion, if QoS assurance methods are not applied, prolonged congestion can cause packet drops, affecting service quality. In some cases, congestion is prolonged and widespread in the network, which can easily lead to the network being "frozen", or many packets being dropped, seriously affecting service quality.
Therefore, in this chapter, in sections 3.2 and 3.3, we introduce some typical network traffic load monitoring techniques to predict and prevent congestion before it occurs through the measure of dropping (removing) packets early when there are signs of impending congestion.
3.1. DropTail method
DropTail is a simple, traditional queue management method based on FIFO mechanism. All incoming packets are placed in the queue, when the queue is full, the later packets are dropped.
Due to its simplicity and ease of implementation, DropTail has been used for many years on Internet router systems. However, this algorithm has the following disadvantages:
− Cannot avoid the phenomenon of “Lock out”: Occurs when 1 or several traffic streams monopolize the queue, making packets of other connections unable to pass through the router. This phenomenon greatly affects reliable transmission protocols such as TCP. According to the anti-congestion algorithm, when locked out, the TCP connection stream will reduce the window size and reduce the packet transmission speed exponentially.
− Can cause Global Synchronization: This is the result of a severe “Lock out” phenomenon. Some neighboring routers have their queues monopolized by a number of connections, causing a series of other TCP connections to be unable to pass through and simultaneously reducing the transmission speed. After those monopolized connections are temporarily suspended,
Once the queue is cleared, it takes a considerable amount of time for TCP connections to return to their original speed.
− Full Queue phenomenon: Data transmitted on the Internet often has an explosion, packets arriving at the router are often in clusters rather than in turn. Therefore, the operating mechanism of DropTail makes the queue easily full for a long period of time, leading to the average delay time of large packets. To avoid this phenomenon, with DropTail, the only way is to increase the router's buffer, this method is very expensive and ineffective.
− No QoS guarantee: With the DropTail mechanism, there is no way to prioritize important packets to be transmitted through the router earlier when all are in the queue. Meanwhile, with multimedia communication, ensuring connection and stable speed is extremely important and the DropTail algorithm cannot satisfy.
The problem of choosing the buffer size of the routers in the network is to “absorb” short bursts of traffic without causing too much queuing delay. This is necessary in bursty data transmission. The queue size determines the size of the packet bursts (traffic spikes) that we want to be able to transmit without being dropped at the routers.
In IP-based application networks, packet dropping is an important mechanism for indirectly reporting congestion to end stations. A solution that prevents router queues from filling up while reducing the packet drop rate is called dynamic queue management.
3.2. Random elimination method – RED
3.2.1 Overview
RED (Random Early Detection of congestion; Random Early Drop) is one of the first AQM algorithms proposed in 1993 by Sally Floyd and Van Jacobson, two scientists at the Lawrence Berkeley Laboratory of the University of California, USA. Due to its outstanding advantages compared to previous queue management algorithms, RED has been widely installed and deployed on the Internet.
The most fundamental point of their work is that the most effective place to detect congestion and react to it is at the gateway or router.
Source entities (senders) can also do this by estimating end-to-end delay, throughput variability, or the rate of packet retransmissions due to drop. However, the sender and receiver view of a particular connection cannot tell which gateways on the network are congested, and cannot distinguish between propagation delay and queuing delay. Only the gateway has a true view of the state of the queue, the link share of the connections passing through it at any given time, and the quality of service requirements of the
traffic flows. The RED gateway monitors the average queue length, which detects early signs of impending congestion (average queue length exceeding a predetermined threshold) and reacts appropriately in one of two ways:
− Drop incoming packets with a certain probability, to indirectly inform the source of congestion, the source needs to reduce the transmission rate to keep the queue from filling up, maintaining the ability to absorb incoming traffic spikes.
− Mark “congestion” with a certain probability in the ECN field in the header of TCP packets to notify the source (the receiving entity will copy this bit into the acknowledgement packet).
Figure 3. 1 RED algorithm
The main goal of RED is to avoid congestion by keeping the average queue size within a sufficiently small and stable region, which also means keeping the queuing delay sufficiently small and stable. Achieving this goal also helps: avoid global synchronization, not resist bursty traffic flows (i.e. flows with low average throughput but high volatility), and maintain an upper bound on the average queue size even in the absence of cooperation from transport layer protocols.
To achieve the above goals, RED gateways must do the following:
− The first is to detect congestion early and react appropriately to keep the average queue size small enough to keep the network operating in the low latency, high throughput region, while still allowing the queue size to fluctuate within a certain range to absorb short-term fluctuations. As discussed above, the gateway is the most appropriate place to detect congestion and is also the most appropriate place to decide which specific connection to report congestion to.
− The second thing is to notify the source of congestion. This is done by marking and notifying the source to reduce traffic. Normally the RED gateway will randomly drop packets. However, if congestion
If congestion is detected before the queue is full, it should be combined with packet marking to signal congestion. The RED gateway has two options: drop or mark; where marking is done by marking the ECN field of the packet with a certain probability, to signal the source to reduce the traffic entering the network.
− An important goal that RED gateways need to achieve is to avoid global synchronization and not to resist traffic flows that have a sudden characteristic. Global synchronization occurs when all connections simultaneously reduce their transmission window size, leading to a severe drop in throughput at the same time. On the other hand, Drop Tail or Random Drop strategies are very sensitive to sudden flows; that is, the gateway queue will often overflow when packets from these flows arrive. To avoid these two phenomena, gateways can use special algorithms to detect congestion and decide which connections will be notified of congestion at the gateway. The RED gateway randomly selects incoming packets to mark; with this method, the probability of marking a packet from a particular connection is proportional to the connection's shared bandwidth at the gateway.
− Another goal is to control the average queue size even without cooperation from the source entities. This can be done by dropping packets when the average size exceeds an upper threshold (instead of marking it). This approach is necessary in cases where most connections have transmission times that are less than the round-trip time, or where the source entities are not able to reduce traffic in response to marking or dropping packets (such as UDP flows).
3.2.2 Algorithm
This section describes the algorithm for RED gateways. RED gateways calculate the average queue size using a low-pass filter. This average queue size is compared with two thresholds: minth and maxth. When the average queue size is less than the lower threshold, no incoming packets are marked or dropped; when the average queue size is greater than the upper threshold, all incoming packets are dropped. When the average queue size is between minth and maxth, each incoming packet is marked or dropped with a probability pa, where pa is a function of the average queue size avg; the probability of marking or dropping a packet for a particular connection is proportional to the bandwidth share of that connection at the gateway. The general algorithm for a RED gateway is described as follows: [5]
For each packet arrival
Caculate the average queue size avg If minth ≤ avg < maxth
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Perfecting the financial mechanism for science and technology activities in universities in Vietnam - 8
Central universities shall submit their tuition fee collection plans to the direct state management agency, the superior management agency and the Ministry of Finance for consideration and comments. In case the tuition fee collection plans of the units do not comply with the prescribed principles for determining tuition fee levels, the financial agency has the right to request the universities to make appropriate adjustments.
Publicity is an important principle in financial management. Publicity of tuition fee collection plans of universities aims to ensure the right of learners to proactively choose schools and training programs, strengthen the management of competent State agencies and the supervisory role of the people in the activities of units. Tuition fee collection plans of universities must be made public to the admission subjects before organizing the admission registration work.
Sixth , specify the content of expenditure from tuition fees.
Specific regulations on the content of expenditure from tuition fees aim to ensure that tuition fees collected from learners are used for the right purpose of covering direct costs related to providing educational services to learners; accounting for tuition fees is transparent, avoiding commercialization in education.
Agree with the provisions of Decree 43/2006/ND-CP to remove the regulation that public universities must set aside at least 35% (education sector), 45% (training sector) of tuition fees to strengthen facilities and the tuition fee rate to support general management and regulation work of the education and training sector at the local level. Because, also according to the provisions of Decree 43/2006/ND-CP, public educational institutions with tuition fee revenue must set aside at least 25% of the difference between revenue and expenditure in the fiscal year after fulfilling their obligations to the State budget (if the difference between revenue and expenditure is greater than
expenditure, greater than one time the annual salary fund of the unit's rank and position) to create a fund for developing career activities. Furthermore, tuition collection is to cover costs directly related to the educational activities of universities.
Seventh, establish an agency to forecast the occupational needs of society as a basis for building a tuition framework suitable for the training capacity of universities.
Currently, the university training structure in Vietnam is unbalanced (mentioned in chapter 2). Therefore, in the coming time, the state needs to conduct surveys to study social needs for each profession. The results of this survey are an important basis for developing policies and regulations related to tuition fees or policies to encourage and support the development of different training fields of universities.
In particular, separate the development and implementation of tuition policy from social policy to ensure resources for better development of public universities.
3.2.1.5. Perfecting the mechanism for allocating state budget expenditure estimates for higher education
To perfect the mechanism for allocating the State budget expenditure estimate for education, the following State budget allocation models can be referred to.
Reforms in the financing of public higher education over the past several years have raised a number of pressing issues that have drawn particular attention from researchers and administrators around the world. The most important reforms in this area have been the allocation of central government quotas to universities and reforms in budget allocation.
The World Bank's study on higher education policies and practices has drawn four types of models for allocating state budget to universities [33], namely:
-> The model is based on the policy of “negotiation”. This method is rarely used because it does not encourage efficient activities and makes it difficult to adjust resources when the situation changes.
-> The “input-based” budget allocation model. This model is preferred over the “negotiated” budget model, but it does not encourage efficiency enough. It reflects the difference in costs but does not encourage schools to reduce costs or improve quality compared to the norm.
-> The “output-based” model. This model links funding to performance. The performance indicator used to determine the level of funding is based on the number of graduates. This is a more accurate measure of educational effectiveness than the “input-based” model, especially in cases where dropout and repetition rates are high. When studying the cases of Australia, Denmark, and the Netherlands; the World Bank concluded that: applying the output-based funding formula
This leads to a reduction in student attrition and an improvement in the overall efficiency of the public higher education system and the efficiency of resource use.
-> “Quality-based” model; The aim of this funding mechanism is to promote competition between universities to improve quality and thus attract the best students. Currently only Chile is experimenting with this model.
In Vietnam today, the choice of the “input-based” budget allocation model for many years has not encouraged efficiency. This is one of the manifestations of the inadequacies in the state budget management mechanism in higher education. Therefore, the state budget allocation mechanism for universities needs to be improved.
Choosing a budget allocation model for public universities in Vietnam.
Budget allocation “based on output” or based on the number of graduates with jobs is a method being applied in some countries on the basis of a standard quality assessment system. However, the mechanism is difficult to apply to Vietnam, but it should be studied and tested. Because the rate of students with jobs and working in the right field is the indicator that shows the highest training efficiency. In particular, according to the author, the basis for allocating the state budget to public universities should be considered from the system of indicators that the author mentioned in chapter 1.
In order to apply the “output-based” budget allocation model, it is necessary to build an information system that updates annually on the survey of employed graduates from the school level; publish all output products linked to the financial management assessment indicator system of public universities, which means:
-> Help schools get closer to the needs of the labor market.
-> Provide accurate information as a basis for policy-making and budget-allocation agencies to review and finalize the new budget allocation mechanism.
-> Is a useful and necessary information channel for learners to make decisions about choosing a suitable career.
The annual survey of graduates is a very new approach for Vietnam. Within the framework of the higher education project, most schools must participate in the survey; this work has been and is being completed to ensure the accuracy and high reliability of the information.
Complete, develop and implement the contract and bidding mechanism for providing educational services ordered by the State.
3.2.1.6. Perfecting the State's legal policy system on public financial management
To increase financial resources in public universities and effectively use these financial resources, the Ministry of Finance needs to develop a plan to supplement other legal documents, more specifically Decree No. 43/2006/ND-CP dated April 25, 2006. Policy makers should
Unify regulations in current legal documents to avoid the situation where the same content has many documents regulating different handling and resolution. Issuing legal and sub-law documents on the one hand avoids overlap, on the other hand creates favorable conditions for units to take advantage of facilities, effectively exploit facilities to generate revenue from joint ventures and associations. For example: According to Decree 43/2006/ND-CP, public service units are allowed to: "Use assets for joint ventures, associations or contribute capital to joint ventures with domestic and foreign organizations and individuals to invest in construction, purchase machinery and equipment to serve service activities in accordance with the functions and tasks of the unit according to current regulations of the State", but the Land Law states that "public land cannot be used for joint ventures and associations ". In addition, the Ministry of Finance also needs to issue timely and appropriate guidance documents for the specific activities of each field, encouraging a number of public universities to convert their operations to private and non-public types. At the same time, regulations and incentive mechanisms should be created when converting to the above types of operations, so that schools can enjoy preferential policies: on taxes, land, and continue to rent or buy back headquarters and assets invested by the State, etc.
Up to now, there have been a number of research projects related to the content of financial autonomy and have made recommendations similar to the author's recommendations. The author hopes that this recommendation will be considered to create a premise for financial autonomy for public universities. Issue regulations allowing schools to be autonomous in enrollment, autonomous in training, and autonomous in tuition fees.
Most public universities and colleges are under the control of ministries, sectors and localities. The ministry that manages the most universities is the Ministry of Education and Training (54 schools – 48 universities and 6 colleges), followed by the Ministry of Health and the Ministry of Culture and Information (6 schools). Many other ministries and sectors manage one or two schools. Some localities that have recently established universities are also considered as the governing bodies of those schools.
With the current management mechanism, there are advantages: helping ministries and branches manage and support schools in terms of finance, human resource organization, scientific research, international cooperation, etc., especially in the early stages of forming the Vietnamese higher education system and in the context of an economy under a centralized planning mechanism. However, after many years of existence, the mechanism of the managing ministry has revealed its limitations and weaknesses. First of all, the closedness within each ministry and branch leads to
to separatism, localism. In many jobs, the governing body becomes an intermediary agency, the school is under the direction of many management agencies. This form loses the initiative and self-responsibility of the school, the unity of the system as well as the pressure increases while the efficiency decreases.
Furthermore, the quality of schools under different ministries and sectors is also difficult to ensure a common level of training level, knowledge standards, narrow program content and lack of flexibility. Not to mention the fact that the schools themselves have a mindset of relying on and waiting for resources from the governing ministry, making the training and scientific research environment extremely passive.
To implement the above solutions related to the management mechanism of the governing ministry is to grant higher autonomy and social responsibility to universities, so that schools have certain autonomy for academic activities, creativity, dynamism and efficiency in school activities, thereby creating breakthroughs and development of each school leading to the development of the entire system in the process of regional and international integration.
The role of the State is to study the autonomy of universities in which areas, to what extent, and to what extent in terms of finance. When granting autonomy to schools, what is the role of the Ministry of Education and Training in the obligation to monitor the quality of education and related management issues.... All transformation mechanisms need to have a roadmap and appropriate steps.
However, this is not easy to do when the habit of thinking about administrative management under the subsidy mechanism of the governing ministry and universities still exists. When there is no full and comprehensive research on the theory and practice of the mechanism of autonomy and social responsibility to have a clear model of the operation of the university system in Vietnam under this mechanism, thinking according to the old mechanism is still a concern in improving the quality of education.
That means it is necessary to carry out reforms in response to the needs and pressures of developing higher education. Therefore, it is necessary to perfect the mechanism of the governing ministry for higher education, thereby creating a large space and environment for the development of higher education on the basis of giving schools autonomy in all aspects, including organization, personnel, finance, and training . At the same time, there needs to be a monitoring process by the University Council. To do this well, it is necessary to establish a general model of the higher education system operating autonomously and taking social responsibility. The powers and responsibilities of state management agencies and universities are also more clearly affirmed. The powers and responsibilities of the Government, ministries, and branches are to develop strategies, directions, development policies as well as long-term plans and annual plans for the development of higher education.
In addition, ensuring financial conditions as well as issuing policies and quality control procedures to develop the training system also play an important role.
The autonomy and self-responsibility of universities are realized through the activities of the university council such as building goals, strategies, directions for operations and development, mobilizing and monitoring the use of resources for the school, regulating policies on the use of finance, assets, etc.
3.2.2. Micro-solution group
3.2.2.1. Diversifying financial sources at public universities
Firstly, there are mechanisms, policies and organizations to mobilize resources from social organizations, associations and businesses into school activities.
On the basis of proposing to the State to soon research and promulgate a mechanism for social organizations, professional associations, and enterprises to participate in proposing and evaluating training and scientific research activities of universities; at the same time, there is a mechanism to mobilize financial resources outside the state budget from social organizations, professional associations, and enterprises to sponsor training and scientific research activities of universities.
- For businesses, who are the direct users of training products, the State needs to have policies to encourage businesses to support training. Business owners themselves say that businesses are willing to financially support training and scientific research activities of universities, but that support money needs to be included in the production costs of the business. Therefore, it is necessary to amend and supplement financial regulations, include it in costs and exempt from corporate income tax revenue for businesses on the support for universities in training and scientific research activities.
- It is necessary to encourage funds to support training, scientific research and technology transfer activities of universities. Currently, funds to support training, scientific research and technology transfer activities of universities have not been developed. Currently, there are a number of funds such as the Scholarship Fund and the Vietnam Technical Innovation Fund, etc. For enterprises, there are currently a number of enterprises that sponsor schools through scholarships for good students. However, the scope and scale are not significant. From the experience of developed countries, the State should soon have a mechanism to encourage enterprises, social organizations, associations, and philanthropists to establish Funds to support training, scientific research and technology transfer. For example, allowing the Fund to be named after the enterprises, social organizations and individuals who founded and sponsored it.
- The State and units co-organize scientific research competitions, search for young talents in universities, thereby building funds to sponsor schools that meet national standards, and move towards building universities that meet international standards.
Second, improve the endogenous capacity of universities. To improve the endogenous capacity of universities, one of the specific solutions has been presented in section 3.2.2.2, further focusing on the following solution:
Promoting the role of the University Council, attracting representatives from businesses to participate in the activities of the Scientific and Training Council in universities. Currently, many universities in advanced countries in the world have implemented a university management mechanism that emphasizes the role of the University Council (SCC). According to them, the SCC is an organization that stands next to and above the board of directors. In the US, the organizational structure of universities is: Chairman of the SCC, General Principal, Principals of member schools, in which the Chairman of the SCC has the highest power. In some countries, the number of members outside the school and members who are students accounts for a large proportion of the SCC structure. In addition to deciding on major issues regarding school development (development strategy, long-term and medium-term plans, determining the school's organizational model, nominating the Principal), the SCC also attaches importance to foreign relations such as: requesting sponsorship, requesting financial contributions from investors, and alumni of the school.
Decision No. 153/2003/QD-TTg dated July 30, 2003 of the Prime Minister on university charters, an important content of the Decision is to establish the Board of Directors in public universities and consider the Board of Directors as an important part of the organizational structure of the university. Decision No. 153/2003/QD-TTg dated July 30, 2003 also clearly defines the organizational structure and nature and role of "the Board of Directors is the management body of the university, the Board of Directors decides on major policies to implement the autonomy and self-responsibility of the university". Accordingly, the Board of Directors has the following tasks: Deciding on the strategic goals and development plans of the university including projects, plans, and medium and long-term development plans in accordance with the planning of the network of State universities; Resolution on the draft regulations on the organization and operation of the school or the additions and amendments to the regulations before the Principal submits them to competent authorities for approval; Resolution on the policy of spending, investment in building facilities, purchasing equipment from the school's own capital; Supervising the implementation of the "regulations on implementing democracy in school activities" issued by the Minister of Education and Training and the Resolutions of the Board of Directors, reporting to the governing body and the Ministry of Education and Training.
The establishment of the Board of Directors is necessary because in the socialist-oriented market mechanism, higher education according to WTO regulations is a type of service activity, not a career activity as we have long considered. Universities must operate according to the mechanism of enterprises, with a Board of Directors - Board of Directors and an executive organization - the Principal. When implementing Resolution No. 14/2005/NQ-CP dated November 2, 2005 of the Government on fundamental and comprehensive innovation of Vietnamese higher education in the period 2006-2010, the autonomy and social responsibility of universities are enhanced. As the legal representative and directly responsible for managing and operating the activities of the school, the Principal will have great power. Therefore,
In addition to implementing the President's management mechanism, there needs to be a mechanism for deciding major policies and supervising the University Council to implement the university's autonomy and self-responsibility and to operate effectively, ensuring the safety of the President's decisions. Thus, only when the autonomy and social responsibility of public universities are enhanced, will the University Council be necessary. Because, according to the current mechanism, schools operate mainly according to the request mechanism.
- for and under the strict and restrictive management of the Ministry, what is the purpose of organizing the Board of Directors and what issues can it decide on in the development of the school? Indeed, the school exists and develops with funds allocated from the State budget, regular expenses, basic construction expenses and even tuition fees according to the State's regulations, with quotas over 100 million VND requiring the Ministry's approval. The school recruits students according to the Ministry's approved quota and the Ministry organizes the entrance exams for the schools. That means: in fact, the Ministry has controlled all issues related to school development from strategy, long-term and medium-term plans to operations.
Up to July 2007, nationwide, a number of public universities have established the University Council and put the Council into operation such as: University of Transport, National Economics University, Ho Chi Minh City University of Economics, Tay Nguyen University, Academy of Finance and Accounting... and a number of universities are in the process of preparing to establish such as: University of Commerce, Foreign Trade University, Hanoi Pedagogical University, University of Agriculture 1.
There is no practical basis and there is not enough time to fully evaluate the role and effect of the Board of Directors on public schools that have established Boards. However, through a survey, in some schools with Boards, I have seen that: the role of the Board of Directors in school activities is still vague, the activities of the Board of Directors are still confusing, the management content of the Board of Directors is not specific, and the effectiveness and efficiency of activities are not high.
The main reason for this situation is that: the establishment of the Board of Directors is not really urgent when the State and the Ministry have not yet granted autonomy and self-responsibility to universities. When the Board of Directors still does work that overlaps with the leadership activities of the Party Committee of the school; State documents do not have specific instructions on the activities of the Board of Directors and the superior management agency, there is no monitoring.
monitoring the direction of the Board of Directors; the Board of Directors' personnel organization is too thin, lacking representatives of businesses, so the mobilization of intellectual and financial resources from society is still limited. The role of the school board has not really been promoted, it is just a formality, the operating regulations are unclear, not public, after some schools have established the Board of Directors, the results and the level of influence on the school's activities have not been publicized, there has not been any conference to summarize and evaluate the necessity and solutions for the Board of Directors' activities.
To promote the role of the Board of Directors in terms of financial autonomy, I propose the following issues:
+ Schools that do not have a Board of Directors need to urgently establish a Board of Directors according to the Ministry's guidance.