Solving work, output results and reorganizing the workforce... to improve task performance and save costs to increase income for cadres and civil servants.
Fifth: The inspection of the management and use of the State budget of the units is not really regular, usually periodic inspection after completing a stage of the financial management cycle (incorporated annual settlement inspection, periodic audit). Therefore, the detection of errors and measures to adjust each stage of the financial management cycle (estimate preparation, allocation, assignment of estimates, settlement...) have not been timely to correct the shortcomings in financial management work.
Sixth: in the process of implementing the autonomy mechanism, units and individuals have not paid attention to evaluating, classifying and ranking civil servants to have a form of reward for collectives and individuals with achievements in improving work efficiency at the lowest cost, which somewhat reduces the effectiveness of the autonomy mechanism and has not fully exploited the potential and creativity of civil servants in performing their tasks.
Seventh: Some units have not recruited enough staff while the annual administrative management budget is allocated according to the assigned planned staff, so they have higher additional income than units that have recruited enough staff. Therefore, looking at the level of additional income expenditure does not accurately assess the unit's ability to save costs.
2.3.2.2 Causes of existence and limitations
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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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Factors Affecting the Implementation of Ktqt in Jordan -
Factors Affecting the Training Activities to Improve State Administrative Management Capacity for Secondary School Principals of the Department of Education - -
Factors Affecting the Implementation of the Digitalization Policy of Terrestrial Television Broadcasting in Dak Lak Province
Firstly, because the construction of a fixed rate close to reality is a difficult problem, requiring the basis of actual use over many periods, analyzing related factors to build a fixed rate to ensure the most effective, consistent with market prices, consistent with the financial capacity of the agency or unit. However, the ability to monitor and track expenditures as a basis for building fixed rates of the administrative and accounting apparatus is still limited; the budget allocated for autonomous regular expenditures (outside the salary fund) is still low, so it is not encouraged for affiliated units to build fixed rates of expenditure. Due to the difficulty in funding sources for implementing the fixed rate of expenditures, the operating fixed rate has increased. Specifically, in the period of 2017 - 2018, the regular expenditure rate increased, but included expenditures for labor contracts according to Decree No. 68/2000/ND-CP (salaries and other expenses).
regular activities) into the norm, so in reality the regular expenditure norm does not increase while market prices increase, so the State Audit Office has difficulty in funding to implement the contract.
Second: due to the State's policy mechanism allowing the preparation of budget estimates according to the assigned payroll (including the payroll that has not been fully recruited) based on the State budget allocation norms, there are certain limitations such as: the budget allocation norms are not really linked to the criteria for ensuring the quality of performing professional tasks, the responsibility between the assigned budget and the level of work completion has not been clarified. The budget allocation norms have not been adjusted to suit reality and have not fully calculated factors related to industry characteristics and market fluctuations.
Third: the policy mechanism allows the use of administrative management funds for the staff quota that has not been fully recruited. Therefore, looking at the level of additional income expenditure does not accurately assess the unit's ability to save costs.
Fourth: the settlement work is not yet linked to output results, volume, quality of work and level of completion of assigned tasks because the State does not have a system of indicators and standards to evaluate the performance of units to encourage cadres and civil servants to strive to complete assigned tasks as well as to make efforts in using administrative management costs economically.
Fifth letter: The spending on rewards for collectives and individuals with achievements is still limited because criteria have not been established to evaluate the annual work efficiency of cadres and civil servants. In addition, the awareness of voting for titles and considering the emulation achievements of civil servants is not objective and does not accurately reflect the work results of the elected persons.
Sixth: The inspection of management and use of regular autonomous funds of units is not regular because the work of advising on the development of periodic and unscheduled inspection plans of level I budget units has not been focused on.
2.3.3 Factors affecting the implementation of the autonomy mechanism at the State Audit Office
Firstly: Administrative management costs assigned to the State Audit Office to implement the autonomous regime are allocated according to the State budget allocation norms based on the payroll approved by competent authorities.
approval; meanwhile, the workload of the State Audit Office due to the requirement of increasing tasks according to the 2015 State Budget Law and the 2015 State Audit Law, the State currently does not have a valid basis to regulate the ratio between the volume of professional work and the number of staff, leading to the need for spending money not being completely proportional to the large volume of work assigned. The budget allocation norms have not paid attention to the characteristics of the industry, which often requires traveling to units across the country and over a large area, so the cost of attention and travel allowances is relatively large; besides, the system of offices and equipment invested by the State is modern and needs to ensure sufficient financial resources for operation; meanwhile, the autonomous budget is still limited, the budget allocation norms are low, not meeting actual needs; therefore, saving expenses to increase income for workers and setting up funds is very difficult...
Second: According to the provisions of the mechanism, the administrative management budget assigned to implement the autonomous regime, in addition to serving the regular operating expenses such as: salaries, wages, salary allowances, payment for public services, office supplies, information, propaganda, communication, conferences..., also includes the cost of purchasing assets. However, the mechanism does not clearly stipulate which assets are assigned in the estimate in the autonomous budget; thus, affecting the allocation of funds and determining the savings of the unit.
Third: One of the basic objectives of the autonomy and self-responsibility regime for the use of administrative management funds for state agencies as stipulated in Article 2 of Decree No. 130/2005/ND-CP is to exercise autonomy while simultaneously associating it with the responsibility of the Head of the unit. However, this has not been clearly demonstrated.
Fourth: Regarding the internal spending regulations of the agency, it is still necessary to base on the current spending regimes, standards, and norms issued by the competent state agency; the spending levels, spending regimes, and norms in the internal spending regulations must not exceed the regimes, standards, and norms issued by the competent state agency. In case the internal spending regulations of the agency are established beyond the regimes, standards, and norms issued by the competent agency, the superior management agency or the financial agency is responsible for requesting the agency issuing the internal spending regulations to make appropriate adjustments.
Fifth letter: Expenditures must be made with legal and valid vouchers and invoices according to regulations (except for lump sum payments for business travel expenses, home phone charges and mobile phone charges for qualified officials); thus, affecting the implementation of lump sum payments for other contents;
Sixth: Savings fund to supplement income for cadres and civil servants according to the coefficient of increasing the maximum salary fund not exceeding 1.0 times compared to the salary level of the rank and position prescribed by the State; regular or unexpected rewards for collectives and individuals; expenses for collective welfare activities, hardship allowances, additional expenses for employees implementing staff streamlining; setting up a reserve fund to stabilize income for cadres and civil servants. With the above regulations, although the head of the agency is given autonomy, he cannot approve or decide on the contents and levels of expenditures exceeding current regulations, cannot decide on the contents of regular operating expenditures outside of State regulations, even from the agency's savings fund. This causes passivity in the organization and implementation of professional tasks of the agency.
Seventh: The budget allocated to the autonomous unit includes both autonomous and non-autonomous budgets, which has made the financial management of the units more complicated. The budget allocated to autonomous units must be managed according to the internal spending regulations of the unit and the standards and norms issued by the competent authority, while the non-autonomous budget must be managed according to current regulations of the State, thus affecting the autonomy level of the unit to some extent.
Eighth: The State Audit Office's job position project has not been approved by competent authorities and there are no guidelines for the criteria for evaluating work volume, quality, time to complete work, and level of task completion, thus affecting the staffing and task performance results and awareness of practicing thrift and fighting waste.
Ninth: The awareness of civil servants about the implementation of the autonomy mechanism of some civil servants is not high, they do not see that the implementation of the autonomy mechanism is to create conditions for heads and civil servants in the unit to proactively use the assigned payroll and budget, associated with the quality and efficiency of work.
Thus, through identifying factors affecting financial management under the autonomous and self-responsible mechanism at the State Audit Office, it helps to orient solutions to improve financial management under the autonomous and self-responsible mechanism at the State Audit Office in chapter 3.
Chapter 2 Conclusion
The author has applied the scientific foundations presented in Chapter 1 to serve the research work in Chapter 2 on the current status of financial management under the mechanism of autonomy and self-responsibility at the State Audit Office. From the actual analysis of the settlement report and the situation of using regular funds at the State Audit Office in the period of 2015 - 2017, it can be seen that basically the mechanism of autonomy and self-responsibility for the use of staff and administrative management funds has promoted efficiency and savings in the use of administrative management funds in accordance with the objectives of the mechanism, ensuring the good completion of assigned tasks and increasing income for cadres, civil servants and employees. In addition, there are also some shortcomings and problems from the mechanism's perspective that need to be innovated, adjusted and built by the Government to build a synchronous legal system suitable to current practice. The research in chapter 2 is an important foundation for the author to propose solutions to improve financial management under the mechanism of autonomy and self-responsibility at the State Audit Office and recommend the Government to improve inappropriate contents in chapter 3.
CHAPTER 3 ORIENTATION AND SOLUTIONS TO IMPROVE FINANCIAL MANAGEMENT UNDER THE MECHANISM OF AUTONOMY AND SELF-RESPONSIBILITY AT THE STATE ARCHITECTURE
3.1 Orientation to perfect financial management work according to the mechanism of autonomy and self-responsibility
3.1.1 General orientation of the State
According to Resolution 30c/NQ-CP dated November 8, 2011 on the overall program of state administrative reform for the period 2011-2020, the Government identified the focus of administrative reform in the next 10 years as: Institutional reform; building and improving the quality of cadres, civil servants and public employees, focusing on reforming salary policies to create real motivation for cadres, civil servants and public employees to perform public duties with high quality and efficiency; improving the quality of administrative services and public services.
Thus, it can be seen that the Government is determined as well as the Government's assessment of the role and importance of Administrative Reform. This is a strong guiding viewpoint for all levels, sectors and the entire Administrative Reform system to actively and effectively implement the reform policies and guidelines deployed in the previous stage, and actively implement the reform tasks in the next stage to carry out administrative reform comprehensively.
In Article 26 of the Law on Practicing, Saving and Combating Wastefulness, the 13th National Assembly stated: "Assigning autonomy and self-responsibility for staffing and finance to agencies and organizations operating with state budget funds when meeting the conditions prescribed by law; encouraging agencies and organizations to assign certain funds to direct managers and users."
Pursuant to the Law on Cadres and Civil Servants 2008, Decree No. 21/2010/ND-CP dated March 8, 2010 of the Government on the management of civil servant payrolls and Decrees of the Government guiding the implementation of the Law on Cadres and Civil Servants. Accordingly, the civil servant payroll is determined on the basis of job positions associated with titles, positions, and civil servant structure by rank; each agency needs to clearly define job positions in order to determine the payroll.
civil servants for recruitment. That is the basis and interconnected solution contributing to determining the correct and sufficient staffing to improve the quality of cadres and civil servants.
According to the roadmap of the Project on reforming salary policy, social insurance and preferential allowances for meritorious people in the period of 2012-2020, the viewpoint of the salary reform policy is to consider salary as a direct investment in people, investment in development, salary is the main source of income for officials and civil servants and reaches a fairly average level in the labor market. Therefore, in the transition period, the State is implementing the roadmap for adjusting the minimum wage (2012-2020), it is necessary to continue to allow the implementation of the mechanism of using savings to increase income for officials and civil servants according to their capacity and work efficiency, in order to create motivation to work, promote labor productivity (because while the salary and income level of officials and civil servants is still limited, there are difficulties). After the salary policy reform roadmap has achieved the target of minimum wage, it is not advisable to continue implementing the mechanism of using savings to increase income for officials and civil servants, because in fact, this is also the budget allocated to serve the activities of state management agencies but is used to increase income; accordingly, when the state implements the minimum wage, it will ensure sufficient and appropriate salary relations, and by 2020, it will summarize the mechanism of autonomy and self-responsibility for the use of administrative management funds for state agencies, to propose to the Government a new appropriate financial management mechanism.
The objective of implementing the mechanism of autonomy and self-responsibility for the use of payroll and administrative management budget for State agencies in the period of 2014-2020 is to continue to perfect and implement the mechanism of autonomy and self-responsibility for the use of payroll and finance for State agencies in order to realize the objective of the 2011-2020 Financial Strategy, which is to build a healthy national financial system, ensure financial security, financial and monetary stability, create conditions to promote rapid and sustainable economic growth, effectively resolve social security issues; mobilize, manage, distribute and use financial resources in society effectively and fairly; promote administrative reform; improve the quality of public service activities, efficiency and effectiveness of State management agencies.
3.1.2 Orientation of State Audit
After 17 years of implementing Resolution No. 927/2010/UBTVQH12 dated April 19, 2010 of the National Assembly Standing Committee on promulgating the State Audit Development Strategy to 2020
to improve the operational capacity, legal validity, quality and efficiency of the State Audit as an effective tool of the State in inspecting, supervising the management and use of the State budget, money and assets; to build a State Audit with high professional qualifications, gradually modernizing, becoming a responsible and prestigious public financial inspection agency, meeting the requirements of the cause of industrialization and modernization of the country, in accordance with international practices and standards. Along with that, an important goal set by the National Assembly for the State Audit agency is to be an important and effective tool of the Party and the State in inspecting and controlling the management and use of the State budget, money and assets; to support and effectively serve the activities of the National Assembly and People's Councils at all levels in performing the function of supervising and deciding on important issues of the country and localities.
The goal of the State Audit is to continue to develop and perfect the organizational system of the State Audit according to the current unified centralized management model, including: advisory units under the executive apparatus, specialized State Audits, regional State Audits and public service units.
Strive to have a synchronous organizational system by 2020, with sufficient structure and force to perform tasks in a streamlined and efficient manner. Develop a human resource development project based on ensuring quantity, reasonable structure and high quality. Promote training and fostering to improve professional ethics, professional qualifications and skills to meet development and integration requirements. Promote comprehensive administrative reform, especially reform of administrative procedures in auditing activities. Strengthen the application of information technology in financial management and professional activities. Continue to save 10% of the annual increase in regular expenditure estimates.
3.2 Solutions to improve financial management under the mechanism of autonomy and self-responsibility at the State Audit Office
Faced with the requirements of socio-economic development and the context of increasingly deep international integration, public finance reform is a very heavy task, especially the task of innovating the financial mechanism of administrative agencies to truly increase the autonomy of agencies and units. Therefore, this