Network Working Group O. Bonaventure
Request for Comments: 2963 FUNDP
Category: Informational S. De Cnodder
Alcatel
October 2000
Network Working Group O. Bonaventure
Request for Comments: 2963 FUNDP
Category: Informational S. De Cnodder
Alcatel
October 2000
A Rate Adaptive Shaper for Differentiated Services
一种用于区分服务的速率自适应整形器
Status of this Memo
本备忘录的状况
This memo provides information for the Internet community. It does not specify an Internet standard of any kind. Distribution of this memo is unlimited.
本备忘录为互联网社区提供信息。它没有规定任何类型的互联网标准。本备忘录的分发不受限制。
Copyright Notice
版权公告
Copyright (C) The Internet Society (2000). All Rights Reserved.
版权所有（C）互联网协会（2000年）。版权所有。
Abstract
摘要
This memo describes several Rate Adaptive Shapers (RAS) that can be used in combination with the single rate Three Color Markers (srTCM) and the two rate Three Color Marker (trTCM) described in RFC2697 and RFC2698, respectively. These RAS improve the performance of TCP when a TCM is used at the ingress of a diffserv network by reducing the burstiness of the traffic. With TCP traffic, this reduction of the burstiness is accompanied by a reduction of the number of marked packets and by an improved TCP goodput. The proposed RAS can be used at the ingress of Diffserv networks providing the Assured Forwarding Per Hop Behavior (AF PHB). They are especially useful when a TCM is used to mark traffic composed of a small number of TCP connections.
本备忘录介绍了几种速率自适应整形器（RAS），它们可分别与RFC2697和RFC2698中描述的单速率三色标记（srTCM）和双速率三色标记（trTCM）结合使用。当TCM用于区分服务网络的入口时，这些RAS通过减少流量的突发性来提高TCP的性能。对于TCP流量，这种突发性的减少伴随着标记数据包数量的减少和TCP goodput的改进。所提出的RAS可用于区分服务网络的入口，提供有保证的每跳转发行为（AF-PHB）。当TCM用于标记由少量TCP连接组成的流量时，它们特别有用。
In DiffServ networks [RFC2475], the incoming data traffic, with the AF PHB in particular, could be subject to marking where the purpose of this marking is to provide a low drop probability to a minimum part of the traffic whereas the excess will have a larger drop probability. Such markers are mainly token bucket based such as the single rate Three Color Marker (srTCM) and two rate Three Color Marker (trTCM) described in [RFC2697] and [RFC2698], respectively.
在DiffServ网络[RFC2475]中，特别是带有AF PHB的传入数据流量可能会受到标记的影响，其中该标记的目的是为流量的最小部分提供较低的丢弃概率，而多余部分将具有较大的丢弃概率。此类标记主要基于令牌桶，如[RFC2697]和[RFC2698]中分别描述的单速率三色标记（srTCM）和双速率三色标记（trTCM）。
Similar markers were proposed for ATM networks and simulations have shown that their performance with TCP traffic was not always satisfactory and several researchers have shown that these performance problems could be solved in two ways:
ATM网络也提出了类似的标记，模拟表明，它们在TCP流量方面的性能并不总是令人满意的，一些研究人员表明，这些性能问题可以通过两种方式解决：
1. increasing the burst size, i.e. increasing the Committed Burst Size (CBS) and the Peak Burst Size (PBS) in case of the trTCM, or
1. 增加突发大小，即在trTCM的情况下增加提交突发大小（CBS）和峰值突发大小（PBS），或
2. shaping the traffic such that a part of the burstiness is removed.
2. 对交通进行整形，以去除部分突发性。
The first solution has as major disadvantage that the traffic sent to the network can be very bursty and thus engineering the network to provide a low packet loss ratio can become difficult. To efficiently support bursty traffic, additional resources such as buffer space are needed. Conversely, the major disadvantage of shaping is that the traffic encounters additional delay in the shaper's buffer.
第一种解决方案的主要缺点是，发送到网络的流量可能非常突发，因此很难对网络进行工程设计以提供较低的分组丢失率。为了有效地支持突发流量，需要额外的资源，如缓冲区空间。相反，整形的主要缺点是流量在整形器的缓冲区中遇到额外的延迟。
In this document, we propose two shapers that can reduce the burstiness of the traffic upstream of a TCM. By reducing the burstiness of the traffic, the adaptive shapers increase the percentage of packets marked as green by the TCM and thus the overall goodput of the users attached to such a shaper.
在本文中，我们提出了两种整形器，它们可以减少TCM上游流量的突发性。通过减少流量的突发性，自适应整形器增加了TCM标记为绿色的数据包的百分比，从而增加了附加到这种整形器的用户的总吞吐量。
Such rate adaptive shapers will probably be useful at the edge of the network (i.e. inside access routers or even network adapters). The simulation results in [Cnodder] show that these shapers are particularly useful when a small number of TCP connections are processed by a TCM.
这种速率自适应整形器在网络边缘（即内部接入路由器或甚至网络适配器）可能很有用。[Cnodder]中的模拟结果表明，当TCM处理少量TCP连接时，这些整形器特别有用。
The structure of this document follows the structure proposed in [Nichols]. We first describe two types of rate adaptive shapers in section two. These shapers correspond to respectively the srTCM and the trTCM. In section 3, we describe an extension to the simple shapers that can provide a better performance. We briefly discuss simulation results in the appendix.
本文件的结构遵循[Nichols]中提出的结构。在第二节中，我们首先描述两种类型的速率自适应整形器。这些整形器分别对应于srTCM和trTCM。在第3节中，我们描述了对简单整形器的扩展，它可以提供更好的性能。我们在附录中简要讨论了模拟结果。
The rate adaptive shaper is based on a similar shaper proposed in [Bonaventure] to improve the performance of TCP with the Guaranteed Frame Rate [TM41] service category in ATM networks. Another type of rate adaptive shaper suitable for differentiated services was briefly discussed in [Azeem]. A RAS will typically be used as shown in figure 1 where the meter and the marker are the TCMs proposed in [RFC2697] and [RFC2698].
速率自适应整形器基于[Bonaventure]中提出的类似整形器，以提高ATM网络中具有保证帧速率[TM41]服务类别的TCP的性能。[Azem]简要讨论了另一种适用于区分服务的速率自适应整形器。RAS通常如图1所示使用，其中仪表和标记是[RFC2697]和[RFC2698]中提出的TCM。
Result
+----------+
| |
| V
+--------+ +-------+ +--------+
Incoming | | | | | | Outgoing
Packet ==>| RAS |==>| Meter |==>| Marker |==>Packet
Stream | | | | | | Stream
+--------+ +-------+ +--------+
Result
+----------+
| |
| V
+--------+ +-------+ +--------+
Incoming | | | | | | Outgoing
Packet ==>| RAS |==>| Meter |==>| Marker |==>Packet
Stream | | | | | | Stream
+--------+ +-------+ +--------+
Figure 1. Rate adaptive shaper
图1。速率自适应整形器
The presentation of the rate adaptive shapers in Figure 1 is somewhat different as described in [RFC2475] where the shaper is placed after the meter. The main objective of the shaper is to produce at its output a traffic that is less bursty than the input traffic, but the shaper avoids to discard packets in contrast with classical token bucket based shapers. The shaper itself consists of a tail-drop FIFO queue which is emptied at a variable rate. The shaping rate, i.e. the rate at which the queue is emptied, is a function of the occupancy of the FIFO queue. If the queue occupancy increases, the shaping rate will also increase in order to prevent loss and too large delays through the shaper. The shaping rate is also a function of the average rate of the incoming traffic. The shaper was designed to be used in conjunction with meters such as the TCMs proposed in [RFC2697] and [RFC2698].
如[RFC2475]中所述，图1中速率自适应整形器的表示有所不同，其中整形器放置在仪表后面。整形器的主要目标是在其输出端产生一个比输入流量突发性小的流量，但与传统的基于令牌桶的整形器相比，整形器避免丢弃数据包。整形器本身由一个尾部丢弃FIFO队列组成，该队列以可变速率清空。成形速率，即队列清空的速率，是FIFO队列占用率的函数。如果队列占用率增加，成形率也将增加，以防止通过成形器的丢失和过大的延迟。整形速率也是传入流量平均速率的函数。该成型机设计用于与[RFC2697]和[RFC2698]中提出的TCMs等仪表结合使用。
There are two types of rate adaptive shapers. The single rate rate adaptive shaper (srRAS) will typically be used upstream of a srTCM while the two rates rate adaptive shaper (trRAS) will usually be used upstream of a trTCM.
有两种类型的速率自适应整形器。单速率自适应整形器（srRAS）通常用于srTCM的上游，而双速率自适应整形器（trRAS）通常用于trTCM的上游。
The srRAS is configured by specifying four parameters: the Committed Information Rate (CIR), the Maximum Information Rate (MIR) and two buffer thresholds: CIR_th (Committed Information Rate threshold) and MIR_th (Maximum Information Rate threshold). The CIR shall be specified in bytes per second and MUST be configurable. The MIR shall be specified in the same unit as the CIR and SHOULD be configurable. To achieve a good performance, the CIR of a srRAS will usually be set to the same value as the CIR of the downstream srTCM. A typical value for the MIR would be the line rate of the output link of the shaper. When the CIR and optionally the MIR are configured, the srRAS MUST ensure that the following relation is verified:
通过指定四个参数来配置SRRA：提交信息速率（CIR）、最大信息速率（MIR）和两个缓冲区阈值：CIR_th（提交信息速率阈值）和MIR_th（最大信息速率阈值）。CIR应以每秒字节数为单位，并且必须是可配置的。MIR应在与CIR相同的单元中指定，并且应可配置。为了获得良好的性能，SRRA的CIR通常将设置为与下游srTCM的CIR相同的值。MIR的典型值是整形器输出链接的线速率。配置CIR和MIR（可选）时，SRRA必须确保验证以下关系：
CIR <= MIR <= line rate
CIR <= MIR <= line rate
The two buffer thresholds, CIR_th and MIR_th shall be specified in bytes and SHOULD be configurable. If these thresholds are configured, then the srRAS MUST ensure that the following relation holds:
两个缓冲区阈值CIR_th和MIR_th应以字节为单位指定，并应可配置。如果配置了这些阈值，则SRRA必须确保以下关系成立：
CIR_th <= MIR_th <= buffer size of the shaper
CIR_th <= MIR_th <= buffer size of the shaper
The chosen values for CIR_th and MIR_th will usually depend on the values chosen for CBS and PBS in the downstream srTCM. However, this dependency does not need to be standardized.
CIR_th和MIR_th的选择值通常取决于下游srTCM中CBS和PBS的选择值。但是，这种依赖性不需要标准化。
The output rate of the shaper is based on two factors. The first one
is the (long term) average rate of the incoming traffic. This
average rate can be computed by several means. For example, the
function proposed in [Stoica] can be used (i.e. EARnew = [(1-exp(-
T/K))*L/T] + exp(-T/K)*EARold where EARold is the previous value of
the Estimated Average Rate, EARnew is the updated value, K a
constant, L the size of the arriving packet and T the amount of time
since the arrival of the previous packet). Other averaging functions
can be used as well.
The output rate of the shaper is based on two factors. The first one
is the (long term) average rate of the incoming traffic. This
average rate can be computed by several means. For example, the
function proposed in [Stoica] can be used (i.e. EARnew = [(1-exp(-
T/K))*L/T] + exp(-T/K)*EARold where EARold is the previous value of
the Estimated Average Rate, EARnew is the updated value, K a
constant, L the size of the arriving packet and T the amount of time
since the arrival of the previous packet). Other averaging functions
can be used as well.
The second factor is the instantaneous occupancy of the FIFO buffer of the shaper. When the buffer occupancy is below CIR_th, the output rate of the shaper is set to the maximum of the estimated average rate (EAR(t)) and the CIR. This ensures that the shaper buffer will be emptied at least at a rate equal to CIR. When the buffer occupancy increases above CIR_th, the output rate of the shaper is computed as the maximum of the EAR(t) and a linear function F of the buffer occupancy for which F(CIR_th)=CIR and F(MIR_th)=MIR. When the buffer occupancy reaches the MIR_th threshold, the output rate of the shaper is set to the maximum information rate. The computation of the shaping rate is illustrated in figure 2. We expect that real implementations will only use an approximate function to compute the shaping rate.
第二个因素是整形器FIFO缓冲区的瞬时占用率。当缓冲区占用率低于CIR_th时，整形器的输出速率设置为估计平均速率（EAR（t））和CIR的最大值。这确保整形器缓冲区将至少以等于CIR的速率清空。当缓冲区占用率增加到CIR_th以上时，整形器的输出速率计算为EAR的最大值（t） 以及缓冲区占用率的线性函数F，其中F（CIR_th）=CIR和F（MIR_th）=MIR。当缓冲区占用率达到MIR_th阈值时，整形器的输出速率设置为最大信息速率。整形速率的计算如图2所示。我们预计实际实现将仅使用近似函数来计算整形速率。
^
Shaping rate |
|
|
MIR | =========
| //
| //
EAR(t) |----------------//
| //
| //
CIR |============
|
|
|
|------------+---------+----------------------->
CIR_th MIR_th Buffer occupancy
^
Shaping rate |
|
|
MIR | =========
| //
| //
EAR(t) |----------------//
| //
| //
CIR |============
|
|
|
|------------+---------+----------------------->
CIR_th MIR_th Buffer occupancy
Figure 2. Computation of shaping rate for srRAS
图2。srRAS成形速率的计算
The trRAS is configured by specifying six parameters: the Committed Information Rate (CIR), the Peak Information Rate (PIR), the Maximum Information Rate (MIR) and three buffer thresholds: CIR_th, PIR_th and MIR_th. The CIR shall be specified in bytes per second and MUST be configurable. To achieve a good performance, the CIR of a trRAS will usually be set at the same value as the CIR of the downstream trTCM. The PIR shall be specified in the same unit as the CIR and MUST be configurable. To achieve a good performance, the PIR of a trRAS will usually be set at the same value as the PIR of the downstream trRAS. The MIR SHOULD be configurable and shall be specified in the same unit as the CIR. A typical value for the MIR will be the line rate of the output link of the shaper. When the values for CIR, PIR and optionally MIR are configured, the trRAS MUST ensure that the following relation is verified:
trRAS通过指定六个参数进行配置：提交信息速率（CIR）、峰值信息速率（PIR）、最大信息速率（MIR）和三个缓冲区阈值：CIR_th、PIR_th和MIR_th。CIR应以每秒字节数为单位，并且必须是可配置的。为了获得良好的性能，TRRA的CIR通常设置为与下游trTCM的CIR相同的值。PIR应在与CIR相同的单元中指定，并且必须是可配置的。为了获得良好的性能，trRAS的PIR通常设置为与下游trRAS的PIR相同的值。MIR应是可配置的，并应以与CIR相同的单位指定。MIR的典型值为整形器输出链路的线速率。当配置CIR、PIR和可选MIR的值时，trRAS必须确保验证以下关系：
CIR <= PIR <= MIR <= line rate
CIR <= PIR <= MIR <= line rate
The three buffer thresholds, CIR_th, PIR_th and MIR_th shall be specified in bytes and SHOULD be configurable. If these thresholds are configured, then the trRAS MUST ensure that the following relation is verified:
三个缓冲区阈值CIR_th、PIR_th和MIR_th应以字节为单位指定，并应可配置。如果配置了这些阈值，则TRRA必须确保验证以下关系：
CIR_th <= PIR_th <= MIR_th <= buffer size of the shaper
CIR_th <= PIR_th <= MIR_th <= buffer size of the shaper
The CIR_th, PIR_th and MIR_th will usually depend on the values chosen for the CBS and the PBS in the downstream trTCM. However, this dependency does not need to be standardized.
CIR_th、PIR_th和MIR_th通常取决于为下游trTCM中的CBS和PBS选择的值。但是，这种依赖性不需要标准化。
The output rate of the trRAS is based on two factors. The first is the (long term) average rate of the incoming traffic. This average rate can be computed as for the srRAS.
trRAS的输出速率基于两个因素。第一个是传入流量的（长期）平均速率。该平均速率可按SRRA计算。
The second factor is the instantaneous occupancy of the FIFO buffer of the shaper. When the buffer occupancy is below CIR_th, the output rate of the shaper is set to the maximum of the estimated average rate (EAR(t)) and the CIR. This ensures that the shaper will always send traffic at least at the CIR. When the buffer occupancy increases above CIR_th, the output rate of the shaper is computed as the maximum of the EAR(t) and a piecewise linear function F of the buffer occupancy. This piecewise function can be defined as follows. The first piece is between zero and CIR_th where F is equal to CIR. This means that when the buffer occupancy is below a certain threshold CIR_th, the shaping rate is at least CIR. The second piece is between CIR_th and PIR_th where F increases linearly from CIR to PIR. The third part is from PIR_th to MIR_th where F increases linearly from PIR to the MIR and finally when the buffer occupancy is above MIR_th, the shaping rate remains constant at the MIR. The computation of the shaping rate is illustrated in figure 3. We expect that real implementations will use an approximation of the function shown in this figure to compute the shaping rate.
第二个因素是整形器FIFO缓冲区的瞬时占用率。当缓冲区占用率低于CIR_th时，整形器的输出速率设置为估计平均速率（EAR（t））和CIR的最大值。这确保整形器始终至少在CIR发送流量。当缓冲区占用率增加到CIR_th以上时，整形器的输出速率计算为EAR（t）的最大值以及缓冲区占用率的分段线性函数F。这个分段函数可以定义如下。第一块介于0和CIR_th之间，其中F等于CIR。这意味着当缓冲区占用率低于某个阈值CIR_th时，成形率至少为CIR。第二块介于CIR_th和PIR_th之间，其中F从CIR到PIR线性增加。第三部分是从PIR_th到MIR_th，其中F从PIR到MIR线性增加，最后当缓冲区占用率高于MIR_th时，成形速率在MIR处保持不变。成形率的计算如图3所示。我们期望实际实现将使用此图中所示函数的近似值来计算成形率。
^
Shaping rate |
|
MIR | ======
| ///
| ///
PIR | ///
| //
| //
EAR(t) |----------------//
| //
| //
CIR |============
|
|
|
|------------+---------+--------+-------------------->
CIR_th PIR_th MIR_th Buffer occupancy
^
Shaping rate |
|
MIR | ======
| ///
| ///
PIR | ///
| //
| //
EAR(t) |----------------//
| //
| //
CIR |============
|
|
|
|------------+---------+--------+-------------------->
CIR_th PIR_th MIR_th Buffer occupancy
Figure 3. Computation of shaping rate for trRAS
图3。trRAS成形速率的计算
3. Description of the green RAS.
3. 绿色RAS的描述。
The srRAS and the trRAS described in the previous section are not aware of the status of the meter. This entails that a RAS could unnecessarily delay a packet although there are sufficient tokens available to color the packet green. This delay could mean that TCP takes more time to increase its congestion window and this may lower the performance with TCP traffic. The green RAS shown in figure 4 solves this problem by coupling the shaper with the meter.
上一节中描述的SRRA和TRRA不知道仪表的状态。这意味着RAS可能会不必要地延迟数据包，尽管有足够的令牌可用于将数据包涂成绿色。这种延迟可能意味着TCP需要更多的时间来增加其拥塞窗口，这可能会降低TCP流量的性能。图4所示的绿色RAS通过将整形器与仪表耦合来解决此问题。
Status Result
+----------+ +----------+
| | | |
V | | V
+--------+ +-------+ +--------+
Incoming | green | | | | | Outgoing
Packet ==>| RAS |==>| Meter |==>| Marker |==>Packet
Stream | | | | | | Stream
+--------+ +-------+ +--------+
Status Result
+----------+ +----------+
| | | |
V | | V
+--------+ +-------+ +--------+
Incoming | green | | | | | Outgoing
Packet ==>| RAS |==>| Meter |==>| Marker |==>Packet
Stream | | | | | | Stream
+--------+ +-------+ +--------+
Figure 4. green RAS
图4。绿色RAS
The two rate adaptive shapers described in section 2 calculate a shaping rate, which is defined as the maximum of the estimated average incoming data rate and some function of the buffer occupancy. Using this shaping rate, the RAS computes the time schedule at which the packet at the head of the queue of the shaper is to be released. The main idea of the green RAS is to couple the shaper with the downstream meter so that the green RAS knows at what time the packet at the head of its queue would be accepted as green by the meter. If this time instant is earlier than the release time computed from the current shaping rate, then the packet can be released at this time instant. Otherwise, the packet at the head of the queue of the green RAS will be released at the time instant calculated from the current shaping rate.
第2节中描述的两个速率自适应整形器计算整形速率，整形速率定义为估计的平均传入数据速率和缓冲区占用的某些函数的最大值。使用该成形速率，RAS计算成形器队列头部的数据包将被释放的时间安排。绿色RAS的主要思想是将整形器与下游计量器耦合，以便绿色RAS知道在什么时候其队列头部的数据包将被计量器接受为绿色。如果该时刻早于根据当前成形速率计算的释放时间，则可以在该时刻释放分组。否则，绿色RAS的队列头部的分组将在根据当前成形速率计算的时刻被释放。
3.2. Configuration of the Green single rate Rate Adaptive Shaper (GsrRAS)
3.2. 绿色单速率自适应整形器（GsrRAS）的配置
The G-srRAS must be configured in the same way as the srRAS (see section 2.2).
G-SRRA的配置方式必须与SRRA相同（见第2.2节）。
First of all, the shaping rate of the G-srRAS is calculated in the same way as for the srRAS. With the srRAS, this shaping rate determines a time schedule, T1, at which the packet at the head of the queue is to be released from the shaper.
首先，G-srRAS的成形率的计算方法与srRAS相同。对于srRAS，该成形速率确定时间调度T1，在该时刻，队列头部的分组将从成形器释放。
A second time schedule, T2, is calculated as the earliest time instant at which the packet at the head of the shaper's queue would be colored as green by the downstream srTCM. Suppose that a packet of size B bytes is at the head of the shaper and that CIR is the Committed Information Rate of the srTCM in bytes per second. If we denote the current time by t and by Tc(t) the amount of green tokens in the token bucket of the srTCM at time t, then T2 is equal to max(t, t+(B-Tc(t))/CIR). If B is larger than CBS, the Committed Burst Size of the srTCM, then T2 is set to infinity.
第二时间日程表T2被计算为最早的时刻，在该时刻，整形器队列头部的分组将被下游srtc着色为绿色。假设大小为B字节的数据包位于整形器的头部，且CIR是srTCM的提交信息速率（以字节/秒为单位）。如果我们用t表示当前时间，用Tc（t）表示srTCM在时间t的令牌桶中的绿色令牌量，那么T2等于max（t，t+（B-Tc（t））/CIR。如果B大于srTCM的提交突发大小CBS，则T2设置为无穷大。
When a packet arrives at the head of the queue of the shaper, it will leave this queue not sooner than min(T1, T2) from the shaper.
当数据包到达整形器队列的头部时，它将在距离整形器不到min（T1，T2）的时间内离开该队列。
The G-trRAS must be configured in the same way as the trRAS (see section 2.4).
G-trRAS的配置方式必须与trRAS相同（见第2.4节）。
First of all, the shaping rate of the G-trRAS is calculated in the same way as for the trRAS. With the trRAS, this shaping rate determines a time schedule, T1, at which the packet at the head of the queue is to be released from the shaper.
首先，G-trRAS的成形率的计算方法与trRAS相同。对于trRAS，该成形速率确定时间调度T1，在该时刻，队列头部的分组将从成形器释放。
A second time schedule, T2, is calculated as the earliest time instant at which the packet at the head of the shaper's queue would be colored as green by the downstream trTCM. Suppose that a packet of size B bytes is at the head of the shaper and that CIR is the Committed Information Rate of the srTCM in bytes per second. If we denote the current time by t and by Tc(t) (resp. Tp(t)) the amount of green (resp. yellow) tokens in the token bucket of the trTCM at time t, then T2 is equal to max(t, t+(B-Tc(t))/CIR,t+(B-Tp(t))/PIR). If B is larger than CBS, the committed burst size, or PBS, the peak burst size, of the srTCM, then T2 is set to infinity.
第二时间日程表T2被计算为最早的时刻，在该时刻，整形器队列头部的分组将被下游trtc着色为绿色。假设大小为B字节的数据包位于整形器的头部，且CIR是srTCM的提交信息速率（以字节/秒为单位）。如果我们用t和Tc（t）（分别为Tp（t））表示当前时间，则T2等于最大值（t，t+（B-Tc（t））/CIR，t+（B-Tp（t））/PIR）。如果B大于srTCM的提交突发大小CBS或峰值突发大小PBS，则T2被设置为无穷大。
When a packet arrives at the head of the queue of the shaper, it will leave this queue not sooner than min(T1, T2) from the shaper.
当数据包到达整形器队列的头部时，它将在距离整形器不到min（T1，T2）的时间内离开该队列。
The shapers discussed in this document assume that the Internet traffic is dominated by protocols such as TCP that react appropriately to congestion by decreasing their transmission rate.
本文中讨论的整形器假设Internet流量由TCP等协议控制，这些协议通过降低传输速率对拥塞做出适当反应。
The proposed shapers do not provide a performance gain if the traffic is composed of protocols that do not react to congestion by decreasing their transmission rate.
如果流量由不通过降低传输速率对拥塞作出反应的协议组成，则所提出的整形器不会提供性能增益。
The shapers discussed in this document can be used where the TCMs proposed in [RFC2697] and [RFC2698] are used. In fact, simulations briefly discussed in Appendix A show that the performance of TCP can be improved when a rate adaptive shaper is used upstream of a TCM. We expect such rate adaptive shapers to be particularly useful at the edge of the network, for example inside (small) access routers or even network adapters.
本文件中讨论的成形器可用于[RFC2697]和[RFC2698]中提出的TCM。事实上，附录A中简要讨论的仿真表明，当在TCM上游使用速率自适应整形器时，TCP的性能可以得到改善。我们期望这种速率自适应整形器在网络边缘特别有用，例如在（小型）接入路由器甚至网络适配器内部。
This document explains how the idea of a rate adaptive shaper can be combined with the srTCM and the trTCM. This resulted in the srRAS and the G-srRAS for the srTCM and in the trRAS and the G-trRAS for the trTCM. Similar adaptive shapers could be developed to support other traffic markers such as the Time Sliding Window Three Color Marker (TSWTCM) [Fang]. However, the exact definition of such new adaptive shapers and their performance is outside the scope of this document.
本文档解释了如何将速率自适应整形器的思想与srTCM和trTCM结合起来。这导致了srTCM的srRAS和G-srRAS以及trTCM的trRAS和G-trRAS。可以开发类似的自适应整形器来支持其他交通标记，例如时间滑动窗口三色标记（TSWTCM）[Fang]。然而，这种新的自适应成形器的确切定义及其性能超出了本文档的范围。
The shapers described in this document have no known security concerns.
本文档中描述的整形器没有已知的安全问题。
The IETF has been notified of intellectual property rights claimed in regard to some or all of the specification contained in this document. For more information consult the online list of claimed rights.
IETF已收到关于本文件所含部分或全部规范的知识产权声明。有关更多信息，请查阅在线权利主张列表。
We would like to thank Emmanuel Desmet for his comments.
我们要感谢埃曼纽尔·德斯米特的评论。
[Azeem] Azeem, F., Rao, A., Lu, X. and S. Kalyanaraman, "TCP-Friendly Traffic Conditioners for Differentiated Services", Work in Progress.
[Azem]Azem，F.，Rao，A.，Lu，X.和S.Kalyanaraman，“区分服务的TCP友好流量调节器”，正在进行中。
[RFC2475] Blake S., Black, D., Carlson, M., Davies, E., Wang, Z. and W. Weiss, "An Architecture for Differentiated Services", RFC 2475, December 1998.
[RFC2475]Blake S.，Black，D.，Carlson，M.，Davies，E.，Wang，Z.和W.Weiss，“差异化服务架构”，RFC 24751998年12月。
[Bonaventure] Bonaventure O., "Integration of ATM under TCP/IP to provide services with a minimum guaranteed bandwidth", Ph. D. thesis, University of Liege, Belgium, September 1998.
[BoaveTure] Bonaventure O.，“ATM在TCP/IP下的集成，提供具有最小保证带宽的服务”，Ph. D.论文，列日大学，比利时，1998年9月。
[Clark] Clark D. and Fang, W., "Explicit Allocation of Best-Effort Packet Delivery Service", IEEE/ACM Trans. on Networking, Vol. 6, No. 4, August 1998.
[Clark]Clark D.和Fang，W.，“尽力而为数据包交付服务的显式分配”，IEEE/ACM Trans。《网络》，第6卷，第4期，1998年8月。
[Cnodder] De Cnodder S., "Rate Adaptive Shapers for Data Traffic in DiffServ Networks", NetWorld+Interop 2000 Engineers Conference, Las Vegas, Nevada, USA, May 10-11, 2000.
[Cnodder]De Cnodder S.，“区分服务网络中数据流量的速率自适应整形器”，NetWorld+Interop 2000工程师会议，美国内华达州拉斯维加斯，2000年5月10-11日。
[Fang] Fang W., Seddigh N. and B. Nandy, "A Time Sliding Window Three Colour Marker (TSWTCM)", RFC 2859, June 2000.
[Fang]Fang W.，Seddigh N.和B.Nandy，“时间滑动窗口三色标记（TSWTCM）”，RFC 28592000年6月。
[Floyd] Floyd S. and V. Jacobson, "Random Early Detection Gateways for Congestion Avoidance", IEEE/ACM Transactions on Networking, August 1993.
[Floyd]Floyd S.和V.Jacobson，“避免拥塞的随机早期检测网关”，IEEE/ACM网络事务，1993年8月。
[RFC2697] Heinanen J. and R. Guerin, "A Single Rate Three Color Marker", RFC 2697, September 1999.
[RFC2697]Heinanen J.和R.Guerin，“单速率三色标记”，RFC 26971999年9月。
[RFC2698] Heinanen J. and R. Guerin, "A Two Rate Three Color Marker", RFC 2698, September 1999.
[RFC2698]Heinanen J.和R.Guerin，“双速率三色标记”，RFC 26981999年9月。
[RFC2597] Heinanen J., Baker F., Weiss W. and J. Wroclawski, "Assured Forwarding PHB Group", RFC 2597, June 1999.
[RFC2597]Heinanen J.，Baker F.，Weiss W.和J.Wroclawski，“保证货运PHB集团”，RFC 25971999年6月。
[Nichols] Nichols K. and B. Carpenter, "Format for Diffserv Working Group Traffic Conditioner Drafts", Work in Progress.
[Nichols]Nichols K.和B.Carpenter，“区分服务工作组流量调节器草案的格式”，正在进行中。
[Stoica] Stoica I., Shenker S. and H. Zhang, "Core-stateless fair queueuing: achieving approximately fair bandwidth allocations in high speed networks", ACM SIGCOMM98, pp. 118-130, Sept. 1998
[Stoica]Stoica I.，Shenker S.和H.Zhang，“核心无状态公平排队：在高速网络中实现近似公平的带宽分配”，ACM SIGCOMM98，第118-130页，1998年9月
[TM41] ATM Forum, Traffic Management Specification, verion 4.1, 1999
[TM41]ATM论坛，流量管理规范，verion 4.11999
Appendix
附录
A. Simulation results
A.模拟结果
We briefly discuss simulations showing the benefits of the proposed shapers in simple network environments. Additional simulation results may be found in [Cnodder].
我们简要地讨论了在简单网络环境中显示所提出的整形器的优点的仿真。其他模拟结果可在[Cnodder]中找到。
To evaluate the rate adaptive shaper through simulations, we use the simple network model depicted in Figure A.1. In this network, we consider that a backbone network is used to provide a LAN Interconnection service to ten pairs of LANs. Each LAN corresponds to an uncongested switched 10 Mbps LAN with ten workstations attached to a customer router (C1-C10 in figure A.1). The delay on the LAN links is set to 1 msec. The MSS size of the workstations is set to 1460 bytes. The workstations on the left hand side of the figure send traffic to companion workstations located on the right hand side of the figure. All traffic from the LAN attached to customer router C1 is sent to the LAN attached to customer router C1'. There are ten workstations on each LAN and each workstation implements SACK-TCP with a maximum window size of 64 KBytes.
为了通过仿真评估速率自适应成形器，我们使用图A.1所示的简单网络模型。在这个网络中，我们考虑使用骨干网络为十对LAN提供LAN互连服务。每个LAN对应于一个未占用的交换式10 Mbps LAN，其中10个工作站连接到客户路由器（图a.1中的C1-C10）。LAN链路上的延迟设置为1毫秒。工作站的MSS大小设置为1460字节。图中左侧的工作站将通信发送到图中右侧的同伴工作站。连接到客户路由器C1的LAN的所有通信发送到连接到客户路由器C1'的LAN。每个LAN上有十个工作站，每个工作站实现SACK-TCP，最大窗口大小为64 KB。
2.5 msec, 34 Mbps 2.5 msec, 34 Mbps
<--------------> <-------------->
\+---+ +---+/
-| C1|--------------+ +--------------|C1'|-
/+---+ | | +---+\
\+---+ | | +---+/
-| C2|------------+ | | +------------|C2'|-
/+---+ | | | | +---+\
\+---+ | | | | +---+/
-| C3|----------+ | | | | +----------|C3'|-
/+---+ | | | | | | +---+\
\+---+ | | | | | | +---+/
-| C4|--------+ +-+----------+ +----------+-+ +--------|C4'|-
/+---+ | | | | | | +---+\
\+---+ +---| | | |---+ +---+/
-| C5|------------| ER1 |-----| ER2 |------------|C5'|-
/+---+ +---| | | |---+ +---+\
\+---+ | | | | | | +---+/
-| C6|--------+ +----------+ +----------+ +--------|C6'|-
/+---+ |||| |||| +---+\
\+---+ |||| <-------> |||| +---+/
-| C7|------------+||| 70 Mbps |||+------------|C7'|-
/+---+ ||| 10 msec ||| +---+\
\+---+ ||| ||| +---+/
-| C8|-------------+|| ||+-------------|C8'|-
/+---+ || || +---+\
\+---+ || || +---+/
-| C9|--------------+| |+--------------|C9'|-
/+---+ | | +---+\
\+---+ | | +----+/
-|C10|---------------+ +---------------|C10'|-
/+---+ +----+\
Figure A.1. the simulation model.
2.5 msec, 34 Mbps 2.5 msec, 34 Mbps
<--------------> <-------------->
\+---+ +---+/
-| C1|--------------+ +--------------|C1'|-
/+---+ | | +---+\
\+---+ | | +---+/
-| C2|------------+ | | +------------|C2'|-
/+---+ | | | | +---+\
\+---+ | | | | +---+/
-| C3|----------+ | | | | +----------|C3'|-
/+---+ | | | | | | +---+\
\+---+ | | | | | | +---+/
-| C4|--------+ +-+----------+ +----------+-+ +--------|C4'|-
/+---+ | | | | | | +---+\
\+---+ +---| | | |---+ +---+/
-| C5|------------| ER1 |-----| ER2 |------------|C5'|-
/+---+ +---| | | |---+ +---+\
\+---+ | | | | | | +---+/
-| C6|--------+ +----------+ +----------+ +--------|C6'|-
/+---+ |||| |||| +---+\
\+---+ |||| <-------> |||| +---+/
-| C7|------------+||| 70 Mbps |||+------------|C7'|-
/+---+ ||| 10 msec ||| +---+\
\+---+ ||| ||| +---+/
-| C8|-------------+|| ||+-------------|C8'|-
/+---+ || || +---+\
\+---+ || || +---+/
-| C9|--------------+| |+--------------|C9'|-
/+---+ | | +---+\
\+---+ | | +----+/
-|C10|---------------+ +---------------|C10'|-
/+---+ +----+\
Figure A.1. the simulation model.
The customer routers are connected with 34 Mbps links to the backbone network which is, in our case, composed of a single bottleneck 70 Mbps link between the edge routers ER1 and ER2. The delay on all the customer-edge 34 Mbps links has been set to 2.5 msec to model a MAN or small WAN environment. These links and the customer routers are not a bottleneck in our environment and no losses occurs inside the edge routers. The customer routers are equipped with a trTCM [Heinanen2] and mark the incoming traffic. The parameters of the trTCM are shown in table A.1.
客户路由器通过34 Mbps链路连接到主干网，在我们的例子中，主干网由边缘路由器ER1和ER2之间的单个瓶颈70 Mbps链路组成。所有客户边缘34 Mbps链路上的延迟已设置为2.5毫秒，以模拟MAN或小型WAN环境。这些链路和客户路由器在我们的环境中不是瓶颈，边缘路由器内部不会发生任何损失。客户路由器配备trTCM[Heinanen2]并标记传入流量。trTCM的参数如表A.1所示。
Table A.1: configurations of the trTCMs
表A.1:TRTCM的配置
Router CIR PIR Line Rate C1 2 Mbps 4 Mbps 34 Mbps C2 4 Mbps 8 Mbps 34 Mbps C3 6 Mbps 12 Mbps 34 Mbps C4 8 Mbps 16 Mbps 34 Mbps C5 10 Mbps 20 Mbps 34 Mbps C6 2 Mbps 4 Mbps 34 Mbps C7 4 Mbps 8 Mbps 34 Mbps C8 6 Mbps 12 Mbps 34 Mbps C9 8 Mbps 16 Mbps 34 Mbps C10 10 Mbps 20 Mbps 34 Mbps
路由器CIR PIR线路速率C1 2 Mbps 4 Mbps 34 Mbps C2 4 Mbps 8 Mbps 34 Mbps C3 6 Mbps 12 Mbps 34 Mbps C4 8 Mbps 16 Mbps 34 Mbps C5 10 Mbps 20 Mbps 34 Mbps C6 2 Mbps 4 Mbps 34 Mbps C7 4 Mbps 8 Mbps 34 Mbps C8 Mbps 12 Mbps 34 Mbps C9 8 Mbps 16 Mbps 34 Mbps C10 10 Mbps 20 Mbps 34 Mbps
All customer routers are equipped with a trTCM where the CIR are 2 Mbps for router C1 and C6, 4 Mbps for C2 and C7, 6 Mbps for C3 and C8, 8 Mbps for C4 and C9 and 10 Mbps for C5 and C10. Routers C6-C10 also contain a trRAS in addition to the trTCM while routers C1-C5 only contain a trTCM. In all simulations, the PIR is always twice as large as the CIR. Also the PBS is the double of the CBS. The CBS will be varied in the different simulation runs.
所有客户路由器均配备trTCM，其中路由器C1和C6的CIR为2 Mbps，C2和C7为4 Mbps，C3和C8为6 Mbps，C4和C9为8 Mbps，C5和C10为10 Mbps。除trTCM外，路由器C6-C10还包含trRAS，而路由器C1-C5仅包含trTCM。在所有模拟中，PIR始终是CIR的两倍。PBS也是CBS的两倍。CBS将在不同的模拟运行中变化。
The edge routers, ER1 and ER2, are connected with a 70 Mbps link which is the bottleneck link in our environment. These two routers implement the RIO algorithm [Clark] that we have extended to support three drop priorities instead of two. The thresholds of the parameters are 100 and 200 packets (minimum and maximum threshold, respectively) for the red packets, 200 and 400 packets for the yellow packets and 400 and 800 for the green packets. These thresholds are reasonable since there are 100 TCP connections crossing each edge router. The parameter maxp of RIO for green, yellow and red are respectively set to 0.02, 0.05, and 0.1. The weight to calculate the average queue length which is used by RED or RIO is set to 0.002 [Floyd].
边缘路由器ER1和ER2通过70 Mbps链路连接，这是我们环境中的瓶颈链路。这两个路由器实现了RIO算法[Clark]，我们已经扩展到支持三个丢弃优先级，而不是两个。对于红色分组，参数的阈值为100和200个分组（分别为最小和最大阈值），对于黄色分组为200和400个分组，对于绿色分组为400和800个分组。这些阈值是合理的，因为每个边缘路由器有100个TCP连接。绿色、黄色和红色的RIO参数maxp分别设置为0.02、0.05和0.1。用于计算RED或RIO使用的平均队列长度的权重设置为0.002[Floyd]。
The simulated time is set to 102 seconds where the first two seconds are not used to gather TCP statistics (the so-called warm-up time) such as goodput.
模拟时间设置为102秒，其中前两秒不用于收集TCP统计数据（所谓的预热时间），如goodput。
For our first simulations, we consider that routers C1-C5 only utilize a trTCM while routers C6-C10 utilize a rate adaptive shaper in conjunction with a trTCM. All routers use a CBS of 3 KBytes. In table A.2, we show the total throughput achieved by the workstations attached to each LAN as well as the total throughput for the green and the yellow packets as a function of the CIR of the trTCM used on the customer router attached to this LAN. The throughput of the red
对于我们的第一个模拟，我们认为路由器C1-C5仅利用TrCTCM，而路由器C6C10与TrTCM结合使用速率自适应整形器。所有路由器都使用3KB的CBS。在表A.2中，我们显示了连接到每个LAN的工作站实现的总吞吐量，以及作为连接到该LAN的客户路由器上使用的trTCM的CIR函数的绿色和黄色数据包的总吞吐量。红色通道的吞吐量
packets is equal to the difference between the total traffic and the green and the yellow traffic. In table A.3, we show the total throughput achieved by the workstations attached to customer routers with a rate adaptive shaper.
数据包等于总流量与绿色和黄色流量之间的差值。在表A.3中，我们显示了通过速率自适应整形器连接到客户路由器的工作站实现的总吞吐量。
Table A.2: throughput in Mbps for the unshaped traffic.
表A.2：未定型流量的吞吐量（以Mbps为单位）。
green yellow total 2Mbps [C1] 1.10 0.93 2.25 4Mbps [C2] 2.57 1.80 4.55 6Mbps [C3] 4.10 2.12 6.39 8Mbps [C4] 5.88 2.32 8.33 10Mbps [C5] 7.57 2.37 10.0
绿黄色总量2Mbps[C1]1.10 0.93 2.25 4Mbps[C2]2.57 1.80 4.55 6Mbps[C3]4.10 2.12 6.39 8Mbps[C4]5.88 2.32 8.33 10Mbps[C5]7.57 2.37 10.0
Table A.3: throughput in Mbps for the adaptively shaped traffic. green yellow total 2Mbps [C6] 2.00 1.69 3.71 4Mbps [C7] 3.97 2.34 6.33 6Mbps [C8] 5.93 2.23 8.17 8Mbps [C9] 7.84 2.28 10.1 10Mbps [C10] 9.77 2.14 11.9
表A.3：自适应形状流量的吞吐量（以Mbps为单位）。绿黄色总量2Mbps[C6]2.00 1.69 3.71 4Mbps[C7]3.97 2.34 6.33 6Mbps[C8]5.93 2.23 8.17 8Mbps[C9]7.84 2.28 10.1 10Mbps[C10]9.77 2.14 11.9
This first simulation shows clearly that the workstations attached to an edge router with a rate adaptive shaper have a clear advantage, from a performance point of view, with respect to workstations attached to an edge router with only a trTCM. The performance improvement is the result of the higher proportion of packets marked as green by the edge routers when the rate adaptive shaper is used.
第一次模拟清楚地表明，从性能角度来看，连接到具有速率自适应整形器的边缘路由器的工作站相对于连接到仅具有trTCM的边缘路由器的工作站具有明显的优势。使用速率自适应整形器时，边缘路由器标记为绿色的数据包比例较高，这是性能提高的结果。
To evaluate the impact of the CBS on the TCP goodput, we did additional simulations were we varied the CBS of all customer routers.
为了评估CBS对TCP goodput的影响，我们对所有客户路由器的CBS进行了额外的模拟。
Table A.4 shows the total goodput for workstations attached to, respectively, routers C1 (trTCM with 2 Mbps CIR, no adaptive shaping), C6 (trRAS with 2 Mbps CIR and adaptive shaping), C3 (trTCM with 6 Mbps CIR, no adaptive shaping), and C8 (trRAS with 6 Mbps CIR and adaptive shaping) for various values of the CBS. From this table, it is clear that the rate adaptive shapers provide a performance benefit when the CBS is small. With a very large CBS, the performance decreases when the shaper is in use. However, a CBS of a few hundred KBytes is probably too large in many environments.
表A.4显示了连接到路由器C1（具有2 Mbps CIR的trTCM，无自适应整形）、C6（具有2 Mbps CIR和自适应整形的trRAS）、C3（具有6 Mbps CIR的trTCM，无自适应整形）和C8（具有6 Mbps CIR和自适应整形的trRAS）的工作站的各种CBS值的总吞吐量。从该表可以清楚地看出，当CBS较小时，速率自适应整形器提供了性能优势。对于非常大的CBS，当使用整形器时，性能会下降。但是，数百KB的CBS在许多环境中可能太大。
Table A.4: goodput in Mbps (link rate is 70 Mbps) versus CBS in KBytes. CBS 2_Mbps_unsh 2_Mbps_sh 6_Mbps_unsh 6_Mbps_sh 3 1.88 3.49 5.91 7.77 10 2.97 2.91 6.76 7.08 25 3.14 2.78 7.07 6.73 50 3.12 2.67 7.20 6.64 75 3.18 2.56 7.08 6.58 100 3.20 2.64 7.00 6.62 150 3.21 2.54 7.11 6.52 200 3.26 2.57 7.07 6.53 300 3.19 2.53 7.13 6.49 400 3.13 2.48 7.18 6.43
表A.4：以Mbps（链路速率为70 Mbps）为单位的goodput与以KB为单位的CBS。CBS 2_Mbps_unsh 2_Mbps_sh 6_Mbps_unsh 6_Mbps_unsh 3 1.88 3.49 5.91 7.77 10 2.97 2.91 6.76 7.08 25 3.14 2.78 7.07 6.73 50 3.12 2.67 7.20 6.64 75 3.18 2.56 7.08 6.58 100 3.20 2.20 2.64 7.00 6.62 150 3.21 2.54 7.11 6.52 200 3.26 2.57 7.07 6.53 300 3.53 2.53 7.13.48 7.43
We use the same scenario as in A.2 but now we use the Green trRAS (G-trRAS).
我们使用与A.2中相同的场景，但现在我们使用绿色trRAS（G-trRAS）。
Table A.5 and Table A.6 show the results of the same scenario as for Table A.2 and Table A.3 but the shaper is now the G-trRAS. We see that the shaped traffic performs again much better, also compared to the previous case (i.e. where the trRAS was used). This is because the amount of yellow traffic increases with the expense of a slight decrease in the amount of green traffic. This can be explained by the fact that the G-trRAS introduces some burstiness.
表A.5和表A.6显示了与表A.2和表A.3相同场景的结果，但成型器现在是G-trRAS。我们发现，与前一种情况（即使用trRAS的情况）相比，成形流量的性能也要好得多。这是因为黄色交通量增加，而绿色交通量略有减少。这可以解释为G-trRAS引入了一些突发性。
Table A.5: throughput in Mbps for the unshaped traffic. green yellow total 2Mbps [C1] 1.10 0.95 2.26 4Mbps [C2] 2.41 1.66 4.24 6Mbps [C3] 3.94 1.97 6.07 8Mbps [C4] 5.72 2.13 7.96 10Mbps [C5] 7.25 2.29 9.64
表A.5：未定型流量的吞吐量（以Mbps为单位）。绿黄色总量2Mbps[C1]1.10 0.95 2.26 4Mbps[C2]2.41 1.66 4.24 6Mbps[C3]3.94 1.97 6.07 8Mbps[C4]5.72 2.13 7.96 10Mbps[C5]7.25 2.29 9.64
Table A.6: throughput in Mbps for the adaptively shaped traffic. green yellow total 2Mbps [C6] 1.92 1.75 3.77 4Mbps [C7] 3.79 3.24 7.05 6Mbps [C8] 5.35 3.62 8.97 8Mbps [C9] 6.96 3.48 10.4 10Mbps [C10] 8.69 3.06 11.7
表A.6：自适应成形流量的吞吐量（以Mbps为单位）。绿黄色总量2Mbps[C6]1.92 1.75 3.77 4Mbps[C7]3.79 3.24 7.05 6Mbps[C8]5.35 3.62 8.97 8Mbps[C9]6.96 3.48 10.4 10Mbps[C10]8.69 3.06 11.7
The impact of the CBS is shown in Table A.7 which is the same scenario as Table A.4 with the only difference that the shaper is now the G-trRAS. We see that the shaped traffic performs much better than the unshaped traffic when the CBS is small. When the CBS is
CBS的影响如表A.7所示，其情景与表A.4相同，唯一的区别是成型机现在是G-trRAS。我们发现，当CBS较小时，成形流量比未成形流量的性能要好得多。当哥伦比亚广播公司
large, the shaped and unshaped traffic performs more or less the same. This is in contrast with the trRAS, where the performance of the shaped traffic was slightly worse in case of a large CBS.
大型、成形和非成形流量的性能大致相同。这与trRAS形成对比，在trRAS中，在大型CBS的情况下，成形流量的性能稍差。
Table A.7: goodput in Mbps (link rate is 70 Mbps) versus CBS in KBytes.
表A.7：以Mbps（链路速率为70 Mbps）为单位的goodput与以KB为单位的CBS。
CBS 2_Mbps_unsh 2_Mbps_sh 6_Mbps_unsh 6_Mbps_sh 3 1.90 3.44 5.62 8.44 10 2.95 3.30 6.70 7.20 25 2.98 3.01 7.03 6.93 50 3.06 2.85 6.81 6.84 75 3.08 2.80 6.87 6.96 100 2.99 2.78 6.85 6.88 150 2.98 2.70 6.80 6.81 200 2.96 2.70 6.82 6.97 300 2.94 2.70 6.83 6.86 400 2.86 2.62 6.83 6.84
CBS 2_Mbps_unsh 2_Mbps_sh 6_Mbps_unsh 6_Mbps_unsh 3 1.90 3.44 5.62 8.44 10 2.95 3.30 6.70 7.20 25 2.98 3.01 7.03 6.93 50 3.06 2.85 6.81 6.84 75 3.08 2.80 6.87 6.96 100 2.99 2.78 6.85 6.88 150 2.98 2.70 6.80 6.80 6.81 200 2.96 2.70 6.82 300 2.94 2.70 6.86 2.86 2.86 2.86 6.86 6.86 6
From these simulations, we see that the shaped traffic has much higher throughput compared to the unshaped traffic when the CBS was small. When the CBS is large, the shaped traffic performs slightly less than the unshaped traffic due to the delay in the shaper. The G-trRAS solves this problem. Additional simulation results may be found in [Cnodder]
从这些模拟中，我们可以看到，当CBS较小时，成形流量比未成形流量具有更高的吞吐量。当CBS较大时，由于整形器中的延迟，整形流量的性能略低于未整形流量。G-trRAS解决了这个问题。其他模拟结果可在[Cnodder]中找到
Authors' Addresses
作者地址
Olivier Bonaventure Infonet research group Institut d'Informatique (CS Dept) Facultes Universitaires Notre-Dame de la Paix Rue Grandgagnage 21, B-5000 Namur, Belgium.
Olivier Bonaventure Infonet研究小组信息研究所（CS系）比利时纳穆尔市巴黎圣母院格兰德加内奇路21号B-5000大学学院。
EMail: Olivier.Bonaventure@info.fundp.ac.be
URL: http://www.infonet.fundp.ac.be
EMail: Olivier.Bonaventure@info.fundp.ac.be
URL: http://www.infonet.fundp.ac.be
Stefaan De Cnodder Alcatel Network Strategy Group Fr. Wellesplein 1, B-2018 Antwerpen, Belgium.
Stefaan De Cnodder Alcatel网络战略集团Fr.Wellesplein 1，B-2018比利时安特卫普。
Phone: 32-3-240-8515 Fax: 32-3-240-9932 EMail: stefaan.de_cnodder@alcatel.be
电话：32-3-240-8515传真：32-3-240-9932电子邮件：stefaan.de_cnodder@alcatel.be
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