TPE(eRAN8.1_01)

eRAN

TPE Feature Parameter Description Issue

01

Date

2015-03-23

HUAWEI TECHNOLOGIES CO., LTD.

Copyright © Huawei Technologies Co., Ltd. 2015. All rights reserved. No part of this document may be reproduced or transmitted in any form or by any means without prior written consent of Huawei Technologies Co., Ltd.

Trademarks and Permissions and other Huawei trademarks are trademarks of Huawei Technologies Co., Ltd. All other trademarks and trade names mentioned in this document are the property of their respective holders.

Notice The purchased products, services and features are stipulated by the contract made between Huawei and the customer. All or part of the products, services and features described in this document may not be within the purchase scope or the usage scope. Unless otherwise specified in the contract, all statements, information, and recommendations in this document are provided "AS IS" without warranties, guarantees or representations of any kind, either express or implied. The information in this document is subject to change without notice. Every effort has been made in the preparation of this document to ensure accuracy of the contents, but all statements, information, and recommendations in this document do not constitute a warranty of any kind, express or implied.

Huawei Technologies Co., Ltd. Address:

Huawei Industrial Base Bantian, Longgang Shenzhen 518129 People's Republic of China

Website:

http://www.huawei.com

Email:

[email protected]

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Huawei Proprietary and Confidential Copyright © Huawei Technologies Co., Ltd.

i

eRAN TPE Feature Parameter Description

Contents

Contents 1 About This Document.................................................................................................................. 1 1.1 Scope.............................................................................................................................................................................. 1 1.2 Intended Audience.......................................................................................................................................................... 1 1.3 Change History............................................................................................................................................................... 1 1.4 Differences Between eNodeB Types.............................................................................................................................. 2

2 Overview......................................................................................................................................... 3 2.1 Background Information.................................................................................................................................................4 2.1.1 TCP-related Terms.......................................................................................................................................................4 2.1.2 TCP-related Processes................................................................................................................................................. 5 2.2 Introduction.................................................................................................................................................................... 7 2.3 Benefits........................................................................................................................................................................... 7 2.4 Architecture.................................................................................................................................................................... 8

3 Technical Description of TPE................................................................................................... 10 3.1 ACK Splitting............................................................................................................................................................... 11 3.2 ACK Control.................................................................................................................................................................11 3.3 Enhanced ACK Control................................................................................................................................................ 11 3.4 MTU Control................................................................................................................................................................ 12

4 Related Features...........................................................................................................................13 5 Network Impact........................................................................................................................... 14 6 Engineering Guidelines............................................................................................................. 15 6.1 When to Use TPE......................................................................................................................................................... 15 6.2 Required Information................................................................................................................................................... 16 6.3 Planning........................................................................................................................................................................ 16 6.4 Deployment.................................................................................................................................................................. 16 6.4.1 Requirements............................................................................................................................................................. 16 6.4.2 Data Preparation........................................................................................................................................................ 17 6.4.3 Precautions.................................................................................................................................................................20 6.4.4 Hardware Adjustment................................................................................................................................................20 6.4.5 Initial Configuration.................................................................................................................................................. 21 6.4.5.1 Using the CME to Perform Batch Configuration for Newly Deployed eNodeBs..................................................21 6.4.5.2 Using the CME to Perform Batch Configuration for Existing eNodeBs............................................................... 21 Issue 01 (2015-03-23)


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Contents

6.4.5.3 Using the CME to Perform Single Configuration.................................................................................................. 22 6.4.5.4 Using MML Commands......................................................................................................................................... 23 6.4.6 Activation Observation..............................................................................................................................................23 6.4.7 Reconfiguration......................................................................................................................................................... 25 6.4.8 Deactivation...............................................................................................................................................................25 6.4.8.1 Using the CME to Perform Batch Configuration................................................................................................... 25 6.4.8.2 Using the CME to Perform Single Configuration.................................................................................................. 26 6.4.8.3 Using MML Commands......................................................................................................................................... 26 6.5 Performance Monitoring...............................................................................................................................................26 6.6 Parameter Optimization................................................................................................................................................ 26 6.7 Troubleshooting............................................................................................................................................................ 26

7 Parameters..................................................................................................................................... 28 8 Counters........................................................................................................................................ 34 9 Glossary......................................................................................................................................... 35 10 Reference Documents............................................................................................................... 36

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1 About This Document

1

About This Document

1.1 Scope This document describes LOFD-001026 TCP Proxy Enhancer (TPE), including its technical principles, related features, network impact, and engineering guidelines. This document applies to the following types of eNodeBs. eNodeB Type

Model

Macro

3900 series eNodeB

Micro

BTS3202E and BTS3203E

LampSite

DBS3900 LampSite

Any managed objects (MOs), parameters, alarms, or counters described herein correspond to the software release delivered with this document. Any future updates will be described in the product documentation delivered with future software releases. This document applies only to LTE FDD. Any "LTE" in this document refers to LTE FDD, and "eNodeB" refers to LTE FDD eNodeB.

1.2 Intended Audience This document is intended for personnel who: l

Need to understand the features described herein

l

Work with Huawei products

1.3 Change History This section provides information about the changes in different document versions. There are two types of changes: Issue 01 (2015-03-23)


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l

1 About This Document

Feature change Changes in features and parameters of a specified version as well as the affected entities

l

Editorial change Changes in wording or addition of information and any related parameters affected by editorial changes. Editorial change does not specify the affected entities.

eRAN8.1 01 (2015-03-23) This issue does not include any changes.

eRAN8.1 Draft A (2015-01-15) Compared with Issue 02 (2014-09-30) of eRAN7.0, Draft A (2015-01-15) of eRAN8.1 includes the following changes. Change Type

Change Description

Parameter Change

Feature change

None

None

Editorial change

Modified the description of network impact. For details, see 5 Network Impact.

None

1.4 Differences Between eNodeB Types The features described in this document are implemented in the same way on macro, micro and LampSite eNodeBs.

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2 Overview

2

Overview

This document describes LOFD-001026 TCP Proxy Enhancer (TPE). As a functional entity on the eNodeB, TPE improves TCP service performance.

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2 Overview

2.1 Background Information 2.1.1 TCP-related Terms Table 2-1 defines TCP-related terms. For details about TCP, see the RFC 793 standard. Table 2-1 TCP-related terms

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Term

Definition

MSS

The maximum segment size (MSS) is the largest amount of payload data (excluding TCP headers) in a single segment sent by TCP from the source end to the peer end. The MSS is negotiated when a TCP connection is established between two ends.

MTU

Maximum transmission unit (MTU) is the largest packet size permitted at a specific protocol layer.

Receive window

The receive window (rwnd for short) specifies the largest amount of data that can be received by the receiver.

Congestion window

The congestion window (cwnd for short) limits the total amount of data that can be sent over a TCP connection. This window frequently changes throughout the communication process of the TCP connection.

Offered window

The offered window indicates the largest amount of data that can be received at a specific point in time by the receiver. This window is used to limit the largest amount of unacknowledged data allowed by the sender.

Send window

The send window indicates the largest amount of data that can be sent by the sender at a point in time. This window is equal to the smaller data amount between cwnd and offered window.

Slow start threshold

When cwnd is larger than or equal to the slow start threshold (ssthresh for short), the TCP connection enters the congestion avoidance phase.


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2 Overview

Term

Definition

RTT

The round trip time (RTT) is the elapsed time between sending a data packet with a particular sequence number and receiving an acknowledgment that covers that sequence number.

DupACK

The duplicate acknowledgment (DupACK) is an ACK whose sequence number is the same as that of the previous ACK. When packet disorder or packet loss occurs during transmission, the receiver responds to the sender with a DupACK.

WS

The WS is a window scaling factor. It is indicated by a 16-bit string and is an optional field in the TCP header. If the TCP window size field in the TCP header does not carry the WS option, the maximum value of rwnd is 65,535 bytes (64 KB). If it carries the WS option, the value of rwnd is greater than 64 KB. For example, WS = 1 indicates that the value of rwnd is 64 KB x 2, namely, 128 KB.

SACK

SACK technology enables the selective retransmission of lost packets instead of the retransmission of all subsequent packets. SACK also enables the receiver to inform the sender of lost packets, retransmitted packets, and packets received in advance. SACK improves transmission efficiency.

ACK

ACK is a TCP packet that contains only one sequence number, which indicates that the packets with an earlier sequence number in the corresponding TCP thread have been received.

Fragmentation

The datagram length is determined based on the TCP payload that is negotiated between communication parties. If the size of a datagram is greater than the MTU at the data link layer, the datagram must be fragmented at the IP layer.

2.1.2 TCP-related Processes Data starts to be sequentially transmitted only after a TCP connection is established through a three-way handshake. During data transmission, TCP automatically adjusts the transmission rate based on transmission conditions indicated by RTT changes to maintain TCP Issue 01 (2015-03-23)


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2 Overview

transmission stability. If the sender detects packet loss caused by a retransmission timeout or reception of DupACKs, the sender adjusts the transmission rate by scaling up or down cwnd. This transmission process complies with TCP Reno, a widely used TCP protocol version. The TCP Reno process consists of four phases: slow start, congestion avoidance, fast recovery, and fast retransmission.Figure 2-1 and Figure 2-2 show these phases in which the slow start threshold (ssthresh) is set to 64 KB. Figure 2-1 Slow start and congestion avoidance

Figure 2-2 Fast retransmission and fast recovery

As specified in RFC 793, in the slow start phase, cwnd is set to twice the MSS. Each time an ACK is received, the value of cwnd is incremented by one MSS (unit: byte). In addition, each TCP connection has a slow start threshold (ssthresh). When the value of cwnd reaches this slow start threshold, the TCP connection enters the congestion avoidance phase. In the congestion avoidance phase, the sender reduces the incremental rate of cwnd to avoid network congestion. Figure 2-1 and Figure 2-2 describes two congestion situations and the corresponding actions. Issue 01 (2015-03-23)


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2 Overview

If...

Then...

No ACK is received before the timer expires

The sender assigns values to ssthresh and cwnd as follows:

Consecutive DupACKs are received

l ssthresh = max {cwnd/2, 2 x MSS} l cwnd = 2 x MSS The sender retransmits the packets for which no ACK is received and then enters the slow start phase, as shown in Figure 2-1. l The TCP connection enters the fast retransmission and fast recovery phases, as shown in Figure 2-2. The sender sets both ssthresh and cwnd to the following value: max {cwnd/2, 2 x MSS}. l Each time a DupACK is received, the value of cwnd is incremented by one MSS until the retransmitted packet is acknowledged. l The sender sets cwnd to the value of ssthresh. The TCP connection enters the congestion avoidance phase again.

If the MSS is too large, fragmentation is required. The length of the datagram is determined based on the TCP payload that is negotiated between communication parties. If the size of a datagram is greater than the MTU at the data link layer, the datagram must be fragmented at the IP layer. A unique identifier is used to identify each datagram. This identifier is copied and included in each fragment after datagram fragmentation. One bit in the identifier indicates whether there are more fragments. The value of this bit is 1 in all fragments except for the last one. The fragment offset field indicates the offset of a fragment to the beginning of the original datagram. After a datagram is fragmented, the total length of each fragment is changed to the length of the fragment. After datagram fragmentation, each fragment has its own IP header and independently selects routes. The fragments are reassembled when they arrive at the target IP address. If any fragment is lost, the entire datagram needs to be retransmitted. If the transmission delays of the fragments differ a lot, the reassembling may fail and the datagram may need to be retransmitted.

2.2 Introduction TCP is a transport layer protocol. It provides reliable end-to-end byte stream delivery services on the Internet and is widely used in email and file transfer services. TCP was originally designed for wired networks. It cannot meet the transmission performance requirements of wireless networks in which problems such as significant delay variations occur. As a functional entity on the eNodeB, TPE buffers and processes TCP packets to improve TCP service performance in different scenarios and improve user experience.

2.3 Benefits TPE involves multiple technologies that provide the following benefits: Issue 01 (2015-03-23)


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2 Overview

ACK Splitting ACK splitting reduces TCP transmission delays in the slow start phase, especially when the transmitted files are small. If the sender is running Windows Server 2003, ACK splitting brings 5% to 20% gains during the transmission of small-sized files (1 MB to 10 MB). If the sender is running Windows 7, Windows Server 2008, or Linux, ACK splitting brings no gains. When the air interface is congested, this function brings no gains.

ACK Control When the transmission bandwidth is close to the air interface bandwidth, ACK control prevents bursts of uplink ACKs and therefore bursts of downlink data to be transmitted. Smooth and steady uplink ACK transmission reduces the downlink packet loss rate and improves downlink TCP transmission performance. ACK control brings 5% to 25% gains for single-thread peak throughput when the transmission bandwidth is narrow (not exceeding 120% of the air interface bandwidth) and the buffer of the transmission device is small, such as 32 KB or 64 KB. ACK control brings no gains in scenarios in which five or more threads are used or the transmission bandwidth is not limited (much larger than the air interface bandwidth).

Enhanced ACK Control Based on ACK control, enhanced ACK control prevents bursts of uplink ACKs on an eNodeB level and brings gains for multi-thread scenarios when the transmission bandwidth is narrow (close to the air interface bandwidth) and the buffer of the transmission device is small, such as 32 KB or 64 KB.

MTU Control MTU control prevents packet fragmentation caused by extremely small MTUs and therefore prevents fragment reassembling failure and fragment loss caused by fragmentation. More threads and transmission delays result in more gains. If a device in the transmission network is faulty, which results in fragment loss, MTU control also brings noticeable gains.

2.4 Architecture To improve TCP service performance, a TPE module is introduced to the eNodeB. The TPE module can establish a TPE entity for specified TCP connections. The TPE entity buffers to improve TCP service performance in slow start and congestion scenarios. Figure 2-3 shows the position of the TPE entity.

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2 Overview

Figure 2-3 TPE entity position

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3 Technical Description of TPE

3

Technical Description of TPE

When TCP is applied in wireless networks, TCP service performance becomes deficient because of significant delay variations in wireless networks. In this situation, the eNodeB uses a TPE module to establish a TPE entity for TCP connections carried on a specified TCP port and improve TCP performance. l

l

In downlink data transmission, TPE adopts the following technologies: –

ACK splitting

–

ACK control

–

Enhanced ACK control

–

MTU control

In uplink data transmission, TPE adopts the following technologies: –

ACK splitting

–

MTU control

NOTE

ACK splitting and MTU control in uplink transmission are the same as those in downlink transmission.

TPE, MTU control, ACK control, and enhanced ACK control can be enabled or disabled through the EnodeBAlgoSwitch.TpeSwitch,TcpMssCtrl.TcpMssCtrlSwitch, TcpAckCtrlAlgo.AckCtrlSwitch, and TCPACKLIMITALG.TCPACKLIMITSWITCHparameters, respectively. NOTE

ACK control and enhanced ACK control conflict when both are enabled. ACK control and enhanced ACK control are used in single-thread and multi-thread scenarios, respectively. All functions provided by ACK control now can be provided by enhanced ACK control. You are advised to use only enhanced ACK control.

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3.1 ACK Splitting ACK splitting is performed in slow start phases to generate multiple ACKs in response to one received packet. In TCP implementation, the sender updates the congestion window size based on the number of received ACKs during slow start and fast retransmission. This indicates that the congestion window size increases with the number of ACKs during the two phases. As a result, ACK splitting is useful for restoring and increasing the TCP transmission rate. Networks are already congested during fast retransmission. Network congestion may deteriorate if ACK splitting increases the TCP transmission rate. Therefore, ACK splitting is used only in the initial slow start phase based on the congestion condition of the buffer queue. If the sender is running Windows Server 2003, ACK splitting brings 5% to 20% gains during the transmission of small-sized files (1 MB to 10 MB). If the sender is running Windows 7, Windows Server 2008, or Linux, ACK splitting brings no gains.

3.2 ACK Control The ACK control function controls the transmission of uplink ACKs. If the number of bytes acknowledged by ACKs during a period specified by TcpAckCtrlAlgo.CtrlTimerLength exceeds the threshold specified by TcpAckCtrlAlgo.DlMaxThroughput / (8 x 1000), other ACKs are buffered and sent during the next period. NOTE

The threshold is not equal to the TcpAckCtrlAlgo.DlMaxThroughput parameter but equal to this parameter divided by 8 x 1000. The reason is that the expected unit of the threshold is byte/ms but the unit of this parameter is bit/s.

ACK control prevents a burst of uplink ACKs and therefore any sharp increase of the transmission rate, which reduces the packet loss rate. ACK control brings 5% to 25% gains for single-thread peak throughput when the transmission bandwidth is narrow (not exceeding 120% of the air interface bandwidth) and the buffer of the transmission device is small, such as 32 KB or 64 KB. ACK control brings no gains in scenarios in which five or more threads are used or the transmission bandwidth is unlimited, for example, much larger than the air interface bandwidth.

3.3 Enhanced ACK Control The enhanced ACK control function controls the uplink ACK traffic on an eNodeB. If the number of ACKs transmitted in each TTI exceeds the threshold specified by the TCPACKLIMITALG.DLTHROUGHPUTTHRESHOLD parameter, the rest of the ACKs are reserved for the next TTI. Enhanced ACK control brings gains for multi-thread scenarios when the transmission bandwidth is narrow (not exceeding 120% of the air interface bandwidth) and the buffer of the transmission device is small, such as 32 KB or 64 KB. Enhanced ACK control brings no gains when the transmission bandwidth of the eNodeB is sufficient (much larger than the air interface bandwidth). Issue 01 (2015-03-23)


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3.4 MTU Control MTU control limits the datagram length. If the size of a datagram is greater than that of the MTU, the datagram must be fragmented at the IP layer. For a TCP connection, the MTU size equals the sum of the MSS, TCP header length, and IP datagram header length. The latter two have fixed values. MTU control changes the MSS of TCP packets to prevent packet fragmentation caused by extremely small MTUs. Packet fragmentation may increase the packet loss rate and decrease the throughput.

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4 Related Features

4

Related Features

Prerequisite Features None

Mutually Exclusive Features None

Impacted Features None

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5 Network Impact

5

Network Impact

System Capacity The entire throughput of a cell increases, the extent of which depends on user habits. However, the increase is not great, because TPE takes effect only in certain scenarios. When the number of UEs is large and the air interface is congested, this function brings no gains.

Network Performance No impact.

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6 Engineering Guidelines

6

Engineering Guidelines

6.1 When to Use TPE When you activate TPE, check whether to enable each function based on the following scenarios:

ACK splitting ACK splitting enables the sender to generate multiple ACKs from one ACK. This process accelerates slow start during initial service startup and the downloading rate of small-sized files. ACK splitting improves the user experience of TCP services and applies to both uplink and downlink transmission. ACK splitting is not recommended when the air interface is congested. When a UE is located near the cell center and is downloading a large file, the download condition is constantly good. TPE can provide a small gain for the downloading rate at the beginning. However, it takes a long time to download the file and this small gain is barely noticeable. Therefore, only subtle gains can be brought to downloading rate and transmission delay.

Enhanced ACK control It is recommended that enhanced ACK control be enabled when the transmission bandwidth is narrow (not exceeding 120% of the air interface bandwidth) to decrease the number of lost TCP packets due to downlink traffic bursts. Enhanced ACK control is also recommended when the transmission bandwidth is close to the air interface bandwidth. Enhanced ACK control brings no gains when the transmission bandwidth is unlimited, for example, three times that of the air interface bandwidth or wider.

MTU Control It is recommended that MTU control be enabled when the path MTU is smaller than the maximum packet size negotiated between the sender and receiver to prevent packet loss, delay increase, and service interruption. Issue 01 (2015-03-23)


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6.2 Required Information ACK Splitting None

Enhanced ACK Control To enable enhanced ACK control, collect information about the transmission bandwidth of the eNodeB, and set the parameters based on the transmission bandwidth.

MTU Control To enable MTU control, the minimum path MTU needs to be collected, and the TcpMssCtrl.TcpMssThd parameter must be set based on the minimum path MTU.

6.3 Planning RF Planning N/A

Network Planning N/A

Hardware Planning N/A

6.4 Deployment 6.4.1 Requirements TPE does not have any requirements for the operating environment and transmission networking. The operator has purchased and activated the license for the feature listed in the following table.

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Feature ID

Feature Name

Model

License Control Item

NE

Sales Unit

LOFD-001 026

TCP Proxy Enhancer (TPE)

LT1S000T PE00

TCP Proxy Enhancer (TPE) (FDD)

Macro eNodeB/ LampSite eNodeB/ BTS3202E

per RRC Connected User

6.4.2 Data Preparation This section describes the data that you need to collect for setting parameters. Required data is data that you must collect for all scenarios. Collect scenario-specific data when necessary for a specific feature deployment scenario. There are three types of data sources: l

Network plan (negotiation not required): parameter values planned and set by the operator

l

Network plan (negotiation required): parameter values planned by the operator and negotiated with the evolved packet core (EPC) or peer transmission equipment

l

User-defined: parameter values set by users.

Required Data The following table describes the parameter that must be set in the EnodeBAlgoSwitch MO to enable or disable TPE. Paramete r Name

Parameter ID

Data Source

Setting Notes

TPE switch

EnodeBAlgoSwitch.TpeSwit ch

Network plan (negotiation not required)

Turn on this switch to enable TPE.

The following table describes the parameters that must be set in the TpeAlgo MO to configure the TCP ports that require TPE entity processing. NOTE

The commonly used TCP ports are as follows: l TCP 20 for data transfer using File Transfer Protocol (FTP) l TCP 80 for hypertext transfer using Hypertext Transfer Protocol (HTTP) l TCP 8080, which is the WWW proxy

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Parameter Name

Parameter ID

Data Source

Setting Notes

TPE Port Number

TpeAlgo.PortList Num


Set this parameter to the number of ports that require TPE entity processing.

TPE Port 1

TpeAlgo.Port1


TPE Port 2

TpeAlgo.Port2


TPE Port 3

TpeAlgo.Port3


TPE Port x (x = 1 to 20) indicates the number of the port that requires TPE entity processing. The number of ports is specified by the TpeAlgo.PortList Num parameter.

TPE Port 4

TpeAlgo.Port4


TPE Port 5

TpeAlgo.Port5


TPE Port 6

TpeAlgo.Port6


TPE Port 7

TpeAlgo.Port7


TPE Port 8

TpeAlgo.Port8


TPE Port 9

TpeAlgo.Port9


TPE Port 10

TpeAlgo.Port10


TPE Port 11

TpeAlgo.Port11


TPE Port 12

TpeAlgo.Port12



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Parameter Name

Parameter ID

Data Source

Setting Notes

TPE Port 13

TpeAlgo.Port13


TPE Port 14

TpeAlgo.Port14


TPE Port 15

TpeAlgo.Port15


TPE Port 16

TpeAlgo.Port16


TPE Port 17

TpeAlgo.Port17


TPE Port 18

TpeAlgo.Port18


TPE Port 19

TpeAlgo.Port19


TPE Port 20

TpeAlgo.Port20


The following table describes the parameters that must be set in the TCPACKLIMITALG MO to configure the switch and threshold for enhanced ACK control.

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Paramete r Name

Parameter ID

Data Source

Setting Description

TCP ACK Limit Switch

TCPACKLIMITALG. TCPACKLIMITSWIT CH


Turn on this switch to enable enhanced ACK control.

DL Throughp ut Threshold

TCPACKLIMITALG. DLTHROUGHPUTTH RESHOLD


This parameter indicates the maximum throughput for enhanced ACK control. It is recommended that you set this parameter based on the transmission bandwidth.


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The following table describes the parameters that must be set in the TcpMssCtrl MO to configure the switch and MSS for MTU control. Paramete r Name

Parameter ID

Data Source

Setting Description

TCP MSS Control Switch

TcpMssCtrl.TcpMssCtrl Switch


Turn on this switch to enable MTU control.

TCP MSS Threshold

TcpMssCtrl.TcpMssThd


This parameter indicates the MSS threshold. If this parameter is set to a small value, for example, a value less than 500, the throughput and transmission efficiency will be negatively affected. You are advised to set this parameter based on the minimum MTU of all devices on the transmission path and consider the IP header, TCP header, GTP-U header, and SeGW packet header overheads. The parameter value is calculated by subtracting the total number of bytes of all headers from the number of bytes of the minimum MTU. The MTUs of transmission devices from the eNodeB to the core network can be obtained by running the TRACERT command on the eNodeB. The parameter value is between 1200 and 1400. In most cases, it is 1380.

Scenario-specific Data None

6.4.3 Precautions TPE does not apply to the TCP connections established after the in-use TPE entities reach the maximum specification of 1000.

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6.4.5 Initial Configuration 6.4.5.1 Using the CME to Perform Batch Configuration for Newly Deployed eNodeBs Enter the values of the parameters listed in the following table in a summary data file, which also contains other data for the new eNodeBs to be deployed. Then, import the summary data file into the Configuration Management Express (CME) for batch configuration. For detailed instructions, see "Creating eNodeBs in Batches" in the initial configuration guide for the eNodeB, which is available in the eNodeB product documentation. Table 6-1 Parameters for TPE MO

Sheet in the Summary Data File

Parameter Group

Remarks

ENOD EBAL GOSW ITCH

Common Data

ENodeBAlgoSwitc h

TPEAlgoSwitch

TPEAL GO

Common Data

TpeAlgo

TCP Port Number / TCP Port 1 / TCP Port 2 / TCP Port 3 / TCP Port 4 / TCP Port 5 / TCP Port 6 / TCP Port 7 / TCP Port 8 / TCP Port 9 / TCP Port 10 / TCP Port 11 / TCP Port 12 / TCP Port 13 / TCP Port 14 / TCP Port 15 / TCP Port 16 / TCP Port 17 / TCP Port 18 / TCP Port 19 / TCP Port 20 A user-defined template is required.

TCPAC KLIMI TALG

Common Data


TCP ACK Limit Switch/ DL Throughput Threshold

TCPM SSCTR L

Common Data


TCP MSS Control Switch/TCP MSS Threshold

6.4.5.2 Using the CME to Perform Batch Configuration for Existing eNodeBs Batch reconfiguration using the CME is the recommended method to activate a feature on existing eNodeBs. This method reconfigures all data, except neighbor relationships, for multiple eNodeBs in a single procedure. The procedure is as follows: Step 1 Choose CME > Advanced > Customize Summary Data File (U2000 client mode), or choose Advanced > Customize Summary Data File (CME client mode), to customize a summary data file for batch reconfiguration. Issue 01 (2015-03-23)


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NOTE

For context-sensitive help on a current task in the client, press F1.

Step 2 Choose CME > LTE Application > Export Data > Export Base Station Bulk Configuration Data (U2000 client mode), or choose LTE Application > Export Data > Export Base Station Bulk Configuration Data (CME client mode), to export the eNodeB data stored on the CME into the customized summary data file. Step 3 In the summary data file, set the parameters in the MOs listed in 6.4.5.1 Using the CME to Perform Batch Configuration for Newly Deployed eNodeBs and close the file. Step 4 Choose CME > LTE Application > Import Data > Import Base Station Bulk Configuration Data (U2000 client mode), or choose LTE Application > Import Data > Import Base Station Bulk Configuration Data (CME client mode), to import the summary data file into the CME. Step 5 Choose (U2000 client mode), or choose Area Management > Planned Area > Export Incremental Scripts (CME client mode), to export and activate the incremental scripts. ----End

6.4.5.3 Using the CME to Perform Single Configuration On the CME, set the parameters listed in the "Data Preparation" section for a single eNodeB. The procedure is as follows: Step 1 In the planned data area, click Base Station in the upper left corner of the configuration window. Step 2 In area 1 shown in Figure 6-1, select the eNodeB to which the MOs belong. Figure 6-1 MO search and configuration window

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NOTE

l To view descriptions of the parameters in the MO, click in area 4 and press F1. l Area 5 displays the details of a selected area-4 entry in vertical format. Click the Details icon to show or hide this area.

Step 3 On the Search tab page in area 2, enter an MO name, for example, CELL. Step 4 In area 3, double-click the MO in the Object Name column. All parameters in this MO are displayed in area 4. Step 5 Set the parameters in area 4 or 5. Step 6 Choose (U2000 client mode), or choose Area Management > Planned Area > Export Incremental Scripts (CME client mode), to export and activate the incremental scripts. ----End

6.4.5.4 Using MML Commands ACK Splitting Run the following command to enable ACK splitting: MOD ENODEBALGOSWITCH: TpeSwitch=TpeAlgoSwitch-1;

Run the MOD TPEALGO command to enable TPE for a specified port. The following is an example: MOD TPEALGO: PortListNum=1, Port1=80;

Enhanced ACK Control Run the MOD TCPACKLIMITALG command to enable enhanced ACK control. The following is an example: MOD TCPACKLIMITALG: TCPACKLIMITSWITCH=ON, DLTHROUGHPUTTHRESHOLD=150000;

MTU Control Run the MOD TCPMSSCTRL command to enable MTU control. The following is an example: MOD TCPMSSCTRL: TcpMssCtrlSwitch=ON, TcpMssThd=1380;

6.4.6 Activation Observation Prerequisites l

The UE can perform services at the peak rate.

l

An FTP network server is available, and port 20 is dedicated to FTP services.

Procedure

ACK Splitting Perform the following operations when a computer running Windows Server 2003 is available, the TcpAckFrequency parameter is set to the default value, and the UE is located near the cell center: Issue 01 (2015-03-23)


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Step 1 Run the following command to enable TPE and then enable the UE to reaccess the network: MOD ENODEBALGOSWITCH:TpeSwitch=TpeAlgoSwitch-1;

Step 2 Log in to the FTP server using DOS and download a 1 MB file. Record the downloading time and throughput. Repeat this step multiple times and obtain the average downloading time and throughput. Step 3 Run the following command to disable TPE and then enable the UE to reaccess the network: MOD ENODEBALGOSWITCH:TpeSwitch=TpeAlgoSwitch-0;

Step 4 Repeat Step 2. Step 5 Compare the average downloading times and throughputs obtained in Step 2 and Step 4. If the average downloading time decreases and the average throughput increases, ACK splitting has been enabled. ----End

Enhanced ACK Control Perform the following operations when a 100 Mbit/s switch, such as Quidway S3900, is deployed between the eNodeB and EPC and a Category-3 UE is available: Step 1 Run the following command to enable enhanced ACK control and then enable the UE to reaccess the network: MOD TCPACKLIMITALG: TCPACKLIMITSWITCH=ON, DLTHROUGHPUTTHRESHOLD=95000;

Step 2 Log in to the FTP server running DOS and download a 500 MB file. Record the downloading time and throughput. Repeat this step at least five times and obtain the average downloading time and throughput. Step 3 Run the following command to disable enhanced ACK control and then enable the UE to reaccess the network: MOD TCPACKLIMITALG: TCPACKLIMITSWITCH=OFF;

Step 4 Repeat Step 2. Compare the results obtained in Step 2 and Step 4. With enhanced ACK control enabled, the average download time decreases and the average throughput increases. ----End

MTU Control Step 1 Log in to the FTP server and download a 1 MB file when MTU control is disabled. Record the payload length using packet capturing. Step 2 Enable MTU control and set the TcpMssThd parameter to a value less than the payload length obtained in Step 1, for example, 1380, enable the UE to reaccess the network and download a 1 MB file, and record the payload length using packet capturing. MOD TCPMSSCTRL: TcpMssCtrlSwitch=ON, TcpMssThd=1380; Step 3 Compare the results obtained in Step 1 and Step 2. If the payload length changes to 1380, MTU control has been enabled. ----End Issue 01 (2015-03-23)


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6.4.7 Reconfiguration N/A

6.4.8 Deactivation 6.4.8.1 Using the CME to Perform Batch Configuration Batch reconfiguration using the CME is the recommended method to deactivate a feature on eNodeBs. This method reconfigures all data, except neighbor relationships, for multiple eNodeBs in a single procedure. The procedure for feature deactivation is similar to that for feature activation described in 6.4.5.2 Using the CME to Perform Batch Configuration for Existing eNodeBs. In the procedure, modify parameters according to the following table. Table 6-2 Parameters for deactivating TPE MO

Sheet in the Summary Data File

Parameter Group

Remarks

ENODEBALGOSW ITCH

Common Data

ENodeBAlgoSwitch

TPEAlgoSwitch

TPEALGO

Common Data

TpeAlgo

TCP Port Number/TCP Port 1/TCP Port 2/TCP Port 3/TCP Port 4/TCP Port 5/TCP Port 6/TCP Port 7/TCP Port 8/TCP Port 9/TCP Port 10/TCP Port 11/TCP Port 12/TCP Port 13/TCP Port 14/TCP Port 15/TCP Port 16/TCP Port 17/TCP Port 18/TCP Port 19/TCP Port 20 User-defined

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TCPACKLIMITAL G

Common Data


TCP ACK Limit Switch/DL Throughput Threshold

TCPMSSCTRL

Common Data


TCP MSS Control Switch/TCP MSS Threshold


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6.4.8.2 Using the CME to Perform Single Configuration On the CME, set parameters according to Table 6-2. For detailed instructions, see 6.4.5.3 Using the CME to Perform Single Configuration for feature activation.

6.4.8.3 Using MML Commands Run the following command to disable ACK splitting: MOD ENODEBALGOSWITCH: TpeSwitch=TpeAlgoSwitch-0;

Run the following command to disable enhanced ACK control: MOD TCPACKLIMITALG: TCPACKLIMITSWITCH=OFF;

Run the following command to disable MTU control: MOD TCPMSSCTRL: TcpMssCtrlSwitch=OFF;

6.5 Performance Monitoring The entire throughput of a cell increases. If the proportion of services, such as downloading or uploading small-sized files and web browsing, is high, counters related to the cell throughput increases noticeably. The extent of a throughput increase varies depending on signal quality and file sizes.

6.6 Parameter Optimization N/A

6.7 Troubleshooting ACK splitting brings no or negative gains for downloading or uploading smallsized files. ACK splitting brings no or negative gains for downloading or uploading small-sized files. It increases the data amount for the sender by processing ACKs to accelerate slow start. Step 1 Run the LST TPEALGO command to check whether the TCP port is included in the list of ports to which TPE applies. If the TCP port is included in the list, go to Step 2. Step 2 Check whether the sender is running Windows 7, Windows Server 2008, or Linux. TPE brings no gains when the sender is running any of these operating systems. If the sender is not running any of these operating systems, go to Step 3. Step 3 Check whether the TCP window or the buffer of the sender is greater than 64 KB. If the TCP window is equal to or less than 64 KB, TPE brings no gain. If the TCP window is greater than 64 KB, contact Huawei technical support. ----End Issue 01 (2015-03-23)


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Fault 4 Fault Description When a UE performs downlink TCP services near the cell center with enhanced ACK control enabled, the UE cannot reach the peak rate. Check whether the TCPACKLIMITALG.DLTHROUGHPUTTHRESHOLD parameter is appropriately set. If it is set to a value greater than 110% or less than 90% of the eNodeB transmission bandwidth, ACK control brings no gains. If the parameter is appropriately set, contact Huawei technical support.

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7 Parameters

7

Parameters

Table 7-1 Parameters MO

Parame ter ID

MML Comma nd

Feature ID

Feature Name

Description

ENodeB AlgoSwi tch

TpeSwit ch

MOD ENODE BALGO SWITC H

LOFD-0 01026

TCP Proxy Enhance r (TPE)

Meaning: Indicates the switch for the TCP Proxy Enhancer (TPE) algorithm. The TPE algorithm uses ACK splitting to increase the data rate of TCP services at the initial stage. If this switch is on, the TPE algorithm is enabled and applies only to UEs that newly access or reaccess the network. If this switch is off, the TPE algorithm is disabled.

TDLOF D-00102 8

LST ENODE BALGO SWITC H

TCP Proxy Enhance r (TPE)

GUI Value Range: TpeAlgoSwitch(TpeAlgoSwitch) Unit: None Actual Value Range: TpeAlgoSwitch Default Value: TpeAlgoSwitch:Off

TcpAck CtrlAlgo

CtrlTim erLengt h

MOD TCPAC KCTRL ALGO LST TCPAC KCTRL ALGO

LOFD-0 01026 / TDLOF D-00102 8

TCP Proxy Enhance r(TPE)

Meaning: Indicates the timer length for the TCP ACK control algorithm. This timer can be used to control traffic of the ACKs to uplink TCP packets, therefore preventing traffic bursts in the downlink. GUI Value Range: 1~255 Unit: ms Actual Value Range: 1~255 Default Value: 1

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7 Parameters

MO

Parame ter ID

MML Comma nd

Feature ID

Feature Name

Description

TcpAck CtrlAlgo

DlMaxT hroughp ut

MOD TCPAC KCTRL ALGO

LOFD-0 01026 / TDLOF D-00102 8


Meaning: Indicates the maximum downlink throughput in the TCP ACK control algorithm. If this parameter is set to 0, the downlink throughput in the TCP ACK control algorithm is not under control.

LST TCPAC KCTRL ALGO

GUI Value Range: 0~4294967295 Unit: bit/s Actual Value Range: 0~4294967295 Default Value: 0

TCPAC KLIMIT ALG

DLTHR OUGHP UTTHR ESHOL D

MOD TCPAC KLIMIT ALG

None

None

LST TCPAC KLIMIT ALG

Meaning: Indicates the maximum downlink service throughput that can be set by the TCP ACK limit algorithm. When this switch is set to on, the ACK burst of downlink TCP services is avoided and the KPIs related to the downlink throughput are improved. GUI Value Range: 1~4194304 Unit: kbit/s Actual Value Range: 1~4194304 Default Value: 153600

TpeAlgo

PortList Num

MOD TPEAL GO LST TPEAL GO

LOFD-0 01026 / TDLOF D-00102 8


Meaning: Indicates the number of ports that enable TCP acceleration. GUI Value Range: 0~20 Unit: None Actual Value Range: 0~20 Default Value: 3

TpeAlgo

Port1


LOFD-0 01026 / TDLOF D-00102 8


Meaning: Indicates port 1 to which TPE is to be applied. GUI Value Range: 0~65535 Unit: None Actual Value Range: 0~65535 Default Value: 20

TpeAlgo

Port2


LOFD-0 01026 / TDLOF D-00102 8



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7 Parameters

MO

Parame ter ID

MML Comma nd

Feature ID

Feature Name

Description

TpeAlgo

Port3

MOD TPEAL GO

LOFD-0 01026 / TDLOF D-00102 8


Meaning: Indicates port 3 to which TPE is to be applied.

LST TPEAL GO

GUI Value Range: 0~65535 Unit: None Actual Value Range: 0~65535 Default Value: 8080

TpeAlgo

Port4


LOFD-0 01026 / TDLOF D-00102 8



TpeAlgo

Port5


LOFD-0 01026 / TDLOF D-00102 8



TpeAlgo

Port6


LOFD-0 01026 / TDLOF D-00102 8



TpeAlgo

Port7


LOFD-0 01026 / TDLOF D-00102 8



TpeAlgo

Port8


LOFD-0 01026 / TDLOF D-00102 8



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7 Parameters

MO

Parame ter ID

MML Comma nd

Feature ID

Feature Name

Description

TpeAlgo

Port9

MOD TPEAL GO

LOFD-0 01026 / TDLOF D-00102 8



LST TPEAL GO


TpeAlgo

Port10


LOFD-0 01026 / TDLOF D-00102 8



TpeAlgo

Port11


LOFD-0 01026 / TDLOF D-00102 8



TpeAlgo

Port12


LOFD-0 01026 / TDLOF D-00102 8



TpeAlgo

Port13


LOFD-0 01026 / TDLOF D-00102 8



TpeAlgo

Port14


LOFD-0 01026 / TDLOF D-00102 8



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7 Parameters

MO

Parame ter ID

MML Comma nd

Feature ID

Feature Name

Description

TpeAlgo

Port15

MOD TPEAL GO

LOFD-0 01026 / TDLOF D-00102 8



LST TPEAL GO


TpeAlgo

Port16


LOFD-0 01026 / TDLOF D-00102 8



TpeAlgo

Port17


LOFD-0 01026 / TDLOF D-00102 8



TpeAlgo

Port18


LOFD-0 01026 / TDLOF D-00102 8



TpeAlgo

Port19


LOFD-0 01026 / TDLOF D-00102 8



TpeAlgo

Port20


LOFD-0 01026 / TDLOF D-00102 8



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7 Parameters

MO

Parame ter ID

MML Comma nd

Feature ID

Feature Name

Description

TCPAC KLIMIT ALG

TCPAC KLIMIT SWITC H

MOD TCPAC KLIMIT ALG

None

None

Meaning: Indicates whether to enable the TCP ACK limit algorithm. When this switch is set to on, the base station limits the ACK data rate of downlink TCP services based on the value of DL Throughput Threshold. In this case, the ACK burst of downlink TCP services is prevented and the KPIs related to the downlink throughput rate are improved, but the packet forwarding capability of boards is affected. When this switch is set to off, the base station does not limit the ACK data rate of downlink TCP services.

LST TCPAC KLIMIT ALG

GUI Value Range: OFF(Off), ON(On) Unit: None Actual Value Range: OFF, ON Default Value: OFF(Off) TcpMss Ctrl

TcpMss CtrlSwit ch

MOD TCPMS SCTRL LST TCPMS SCTRL

LOFD-0 01026 / TDLOF D-00102 8


Meaning: Indicates the switch used to enable or disable the TCP MSS function. If this switch is turned off, TCP packets are transparently transmitted without being processed. If this switch is turned on, the value of the MSS field in each packet for TCP link setups can be modified. GUI Value Range: OFF(Off), ON(On) Unit: None Actual Value Range: OFF, ON Default Value: OFF(Off)

TcpMss Ctrl

TcpMss Thd

MOD TCPMS SCTRL LST TCPMS SCTRL

LOFD-0 01026 / TDLOF D-00102 8


Meaning: Indicates the threshold for the value of the MSS field in packets for TCP link setups. If the TCP MSS function is enabled, the eNodeB first checks the MSS field in each packet for TCP link setups. If the value of the MSS field is greater than the predefined threshold, the eNodeB changes the value of the MSS field to the predefined threshold. Then, the eNodeB recalculates the TCP checksum and retransmits the packet with modified fields. For other packets, the eNodeB transparently transmits them. GUI Value Range: 1~1460 Unit: byte Actual Value Range: 1~1460 Default Value: 1460

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8 Counters

8

Counters

There are no specific counters associated with this feature.

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9 Glossary

9

Glossary

For the acronyms, abbreviations, terms, and definitions, see Glossary.

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10 Reference Documents

10

Reference Documents

1.

RFC 793, "Transmission Control Protocol"

2.

eNodeB Initial Configuration Guide

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TPE(eRAN8.1_01)

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