CHAPTER 3
IMPROVING THE EFFICIENCY OF USING THE MORTGAGE CONTRACT BETWEEN PGBANK QUANG NINH AND CUSTOMERS
3.1. Viewpoint on ensuring the implementation of the mortgage contract between PGbank Quang Ninh and customers
The performance of a property mortgage contract must be carried out in accordance with the conditions ensuring compliance with the law.
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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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The implementation of the TCTS contract depends on the conditions for ensuring the implementation of the law, including the level of perfection of the law, the activities of organizing the implementation of the TCTS contract, the conditions of the organization, the capacity and qualities of the staff, civil servants of state management agencies, supporting agencies, and agencies handling TCTS contract disputes. First of all, the system of TCTS legal norms, once promulgated, will be a tool to regulate social relations. The impact of the system of legal norms is not a separate, independent impact but in a whole of certain relationships and constraints. In addition, the provisions of the law are also guided by many Decrees such as: Decree 163/2006/ND-CP on secured transactions, Decree 11/2011/ND-CP amending and supplementing Decree 163/2006/ND-CP; Decree 83/2010/ND-CP on registration of secured transactions and many Circulars and Joint Circulars of Ministries and branches were issued to guide the application of the above Decrees.
The implementation of property mortgage contracts must be associated with a mechanism to ensure law enforcement: Supportive mechanisms with the participation of many functional agencies such as: notary and certification offices; property registration offices, auction procedures, regulations on civil proceedings when filing a lawsuit, regulations on judgment enforcement are important factors contributing to the effective implementation of TCTS regulations. When perfecting the law, it is necessary to supplement regulations on cases of mortgage with fraudulent elements that will be strictly prohibited, or violations of legal provisions on procedures, processes, conditions, etc. will be declared invalid by the Court when applying the law.
The implementation of a mortgage contract must ensure the uniform application of law: The application of law in general is an activity that demonstrates the power of the state over society. In the process of applying the law to resolve disputes, all circumstances must be considered comprehensively, based on the specific provisions and requirements of legal norms. The uniformity of the application of law is an urgent requirement of the rule of law state and the principles of socialist legality.
Implementing a mortgage contract must pay attention to compatibility with international customs and treaties: This requirement requires systematic study of legislative experience of typical legal systems in the world as well as the region, international treaties to transform and selectively absorb the essence of international regulations and customs to suit reality.
3.2. Some solutions to improve the quality of using mortgage contracts between PGbank Quang Ninh and Customers
3.2.1. Solutions to promote activities of organizing the implementation of property mortgage contracts
It is necessary to review, summarize, and evaluate the practical activities of law enforcement organizations to evaluate and find solutions to eliminate and overcome limitations and shortcomings in the process of organizing the implementation of property mortgage contracts.
Promote activities to disseminate, propagate and educate about laws related to property mortgage; raise legal awareness for officials, civil servants and people. Depending on each target, determine the subject, content, form and method of propaganda, dissemination and legal education accordingly, specifically as follows:
+ For officials and civil servants at state management agencies, it is necessary to open specialized training courses to gain in-depth understanding of legal content, practical situations and how to resolve and handle them.
+ People need to pay attention to the contents of TCTS conditions; rights and obligations in TCTS contracts; methods of resolving TCTS disputes are necessary contents before mortgaging TCTS.
+ Service organizations and legal consultants for people when signing TCTS contracts need to carefully guide these contents to avoid unnecessary mistakes and errors when signing TCTS contracts.
Strengthening and innovating the organization and operation of judicial support organizations, service organizations, legal consultancy and legal aid in society: The organization and operation of these organizations play a very important role in the general implementation of the law of the whole society, as well as in the implementation of TCTS contracts. It contributes to the dissemination of propaganda, legal education, and raising legal awareness for people to sign secured transaction contracts in general and TCTS contracts in accordance with the law, strict in content and form, preventing fraudulent acts or unfortunate mistakes. On the other hand, the operation of these organizations helps the parties in contractual relationships protect their legitimate rights and interests when disputes arise.
3.2.2. Solutions to improve the capacity, responsibility and ethics of bank staff towards customers regarding the procedures for resolving property mortgage contracts
The staff planning is publicly announced to the departments and individual staff members in the planning. The selection of staff members to be included in the planning is a very important step in the staff planning. Based on the requirements and tasks of each position and title, the selection is appropriate and gradually standardized.
It is necessary to innovate the content and methods to improve the planning of cadres. It is necessary to focus on creating cadre resources for planning, including attracting talents, receiving, recruiting and training and fostering the cadre team.
Personnel planning must follow the laws of development and elimination, planned sequential development and sudden development. Those who have been included in the planning, but after a period of time have no development prospects, must be resolutely removed from the planning.
The planning work needs to pay attention to the young staff, giving priority to female staff, ensuring a reasonable structure of young and female staff. Based on the current situation of the staff and the goals, standards, and structure of the staff in the new period, each staff position can select staff with sufficient capacity, professional qualifications, and skills to be ready to replace and continue to inherit.
Regularly summarize and improve the quality of staff planning work to promptly adjust any changes or fluctuations, if any, and overcome subjectivity and satisfaction of staff who have been planned.
Use a combination of different assessment methods for different job positions. The nature of cadres is that they often have to contact and work directly with people and organizations, units, and businesses. Therefore, it is necessary to combine internal assessment methods and external assessment results (from people, agencies, organizations, businesses, etc.) so that the assessment results are more objective and comprehensive.
Assessing cadres is based on the title standards of each cadre, on specific work, specific circumstances and policies, and on specific analysis of the conditions and circumstances in which the cadre is working. Establishing assessment criteria and scales for each title and position, the more specific the easier it is to assess. It must be based on the work results and development potential of the cadre.
Evaluating cadres through the performance of assigned functions and tasks: Evaluating the performance of tasks is an important step in management, through which we can properly evaluate the professional expertise, initiative, creativity, and organization of civil servants. The evaluation of cadres must be based on a developmental perspective, not rigid, narrow-minded, or prejudiced.
It is necessary to develop a system of criteria for evaluating staff according to each position and job title with detailed job descriptions, requirements, tasks of each job position, and the level of work completion. The results of annual staff evaluations need to be analyzed and used as a basis for selecting, screening, transferring, planning, and orienting the development of staff.
It is necessary to conduct training and improve the professional skills, ability to grasp and understand the law, policy mechanisms, and related documents for the staff in charge of appraisal, valuation and signing of mortgage contracts so that they have the ability to access and handle mortgaged assets effectively.
Conduct training courses and seminars on experience in appraisal, valuation and signing of mortgage contracts for PG Bank Quang Ninh assets and other banks.
other customers to learn, selectively absorb experiences to apply in practice.
Arrange a team of staff to do the work of appraisal, valuation and signing of mortgage contracts and staff to handle mortgaged assets and recover debts specialized in each specific field (real estate, means of transport, construction works, goods).
...) so that they can grasp the market situation, have a deeper understanding of the field they manage to help in valuing mortgaged assets and foreclosing assets close to their actual value.
3.2.3. Implement the construction and improvement of the secured transaction registration system, modernize the storage system, connect and exchange secured transaction information.
It is necessary to establish a system of independent agencies to recognize secured transaction registration. Of course, to recognize such secured transaction registration, it is also necessary to check the accuracy and legality of information related to secured assets and the identity of the mortgagor and mortgagee.
The agency registering secured transactions needs to grasp the actual status, changes, and fluctuations of secured assets to provide to interested customers. To ensure the reliability and ability to store, connect, and exchange information about secured transactions, a modern system is needed to ensure the storage and provision of information.
Implement information security for secured transactions; strictly handle officers who disclose customer information without the director's permission.
Expand the transaction system to commune and ward People's Committees and schools. Each of these units needs to have a responsible officer to carry out transactions when required. All transaction processes must apply information technology to save costs and time to resolve contracts.
The storage system needs to be encrypted with modern equipment; minimizing the need for costly written storage, labor maintenance costs, and making it convenient to look up customer information when needed.
3.2.4. Strengthening and consolidating service activities, legal advice, and legal aid in the implementation of property mortgage contracts.
It is necessary to improve the organization, strengthen legal services, legal consultancy, and legal aid activities in society, help agencies and organizations operate according to the law, manage society by law, especially help citizens live and work according to the Constitution and the law.
Increase legal advice points, legal aid in mortgage contract implementation. Collaborate with households and customers in organizing free training on consulting content, turning those people into consulting collaborators for the bank.
Conduct agreements with customers on placing bank signs, profit sharing in consulting activities, successful transactions for each mortgage contract.
Use social networking systems to disseminate legal knowledge when implementing mortgage contracts for customers. At the same time, send information to different subjects to seek and disseminate knowledge in the implementation and procedures of property mortgage contracts.
Banks need to coordinate with the People's Committees of communes and wards, and various consulting organizations and units in disseminating knowledge on contract execution.
3.2.5. Strengthen inspection, supervision and handling of violations related to the signing, liquidation and settlement of disputes over property mortgage contracts.
The work of managing, inspecting and supervising the activities of bank staff in resolving mortgage contracts must be carried out regularly, not waiting for staff to commit serious violations before inspecting and disciplining. Implement a customer participation regime to build and supervise, inspect the activities of bank staff, and receive feedback from customers about the staff's behavior and attitude when contacting customers to resolve contracts.
Conduct inspections and supervision in the strict implementation of discipline in the performance of transaction tasks and contract signing. Unified management is to ensure
for the activities of cadres to be consistent, rhythmic, orderly and towards effectiveness and efficiency. At the same time, conduct periodic cadre assessments to assess cadre capacity (the cycle can be from 3 to 8 months); Determine the number of cadres according to job positions in each agency and unit; Regulate the types of diplomas and certificates for each title.
There should be more specific regulations on inspection and evaluation of staff. That is the condition to ensure that staff carry out transactions, procedures for signing and appraising assets seriously, legally, and effectively. Through inspection and evaluation activities, the above directors will know how capable the staff is in handling mortgage contracts, whether they are correct, and whether there are any errors. If there are violations, timely guidance and correction will be given. Also, through inspection and evaluation, staff will see their strengths and weaknesses so that they can make the right adjustments.
It is necessary to establish regulations on regular and periodic inspection of cadres when assigned to search for and sign mortgage contracts. The results must be publicly announced, and serve as the basis for considering salary increases, for arrangement, promotion, appointment and consideration of other preferential regimes.
Violations must be strictly handled to serve as a deterrent; at the same time, it must be handled as quickly as possible; if there is a serious violation, the officer can be suspended from work immediately. This will create more effectiveness for the implementation of administrative discipline; preventing negativity within the people performing the work.
Develop and perfect the mechanism and policy for inspecting and supervising cadres and implement them in practice. It is necessary to conduct inspections and supervisions to contribute to consolidating and enhancing the effectiveness of the cadre team, detecting and promptly handling cadres who show signs of violating ethics and the law in implementing the procedures for concluding mortgage contracts.
It is necessary to inspect and supervise to ensure correctness and legality from the beginning and during the implementation process. If any violations of the law are detected in these activities, they must be strictly handled according to the provisions of the law.
It is necessary to regularly check and supervise the signing, liquidation and dispute resolution of TCTS contracts because this is a series of closely related activities, in which ensuring the correctness and reliability of the previous activities will ensure the correctness and legality of the following activities and finally limit and eliminate possible TCTS contract disputes.
It is necessary to establish a separate organization to monitor the use of customers' loans to evaluate the credit activities of both the Bank and customers.
3.2.6. Solutions to improve the efficiency of concluding and implementing property mortgage contracts
+ About contract content :
Regarding contract documents and contract interpretation , this clause should clearly state which documents are considered as contract documents such as appendices (for example, a map describing the location of the mortgaged property being a house), separate agreements in order of priority. When there is a conflict regarding the interpretation of the contract, these documents can be referred to in the order specified. This clause is meant to be a pre-emptive measure when the parties disagree on the interpretation of the language stated in the contract. This clause should be written after the clause on the subject to make the contract clearer.
Regarding the terms of rights and obligations , in general, the model mortgage contract has provided relatively complete and specific provisions in some contents. However, it is still necessary to supplement more in the direction of specifying obligations such as the obligation to register secured transactions, specifically about the time of performance in each obligation.
Regarding the provision on handling violations , it is necessary to clearly define what acts are considered to be in breach of contract and what the penalties are for each specific act. Such clear provisions will help the penalty clause to be implemented smoothly in practice. When one party commits the acts specified in the penalty clause, the other party will have the right to immediately apply the agreed sanctions. The current provisions in the Branch's mortgage contract form are still unclear and ambiguous, so they do not ensure the feasibility and predictability of the contract; therefore, the Branch should amend this provision in the above direction.