e6474a drive test tool ftp ipv4ipv6 testing explained

7/24/2019 E6474A Drive Test Tool FTP IPv4IPv6 Testing Explained

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Application Note

WEBSITE:www.jdsu.com/test

E6474A Drive Test Tool FTP IPv4/IPv6 Testing ExplainedBy: Fabien Pinardon

Introduction

A key feature of the E6474A Drive est tool is its data test capabilities, including FP testing of the CP-IP layer.his document shows some typical testing scenarios that highlight the capabilities of using the FP IPv4/IPv6test.

Network troubleshooting- a simple FP transaction can help identify network failures, traffic problems andhighlight performance issues.

Network benchmarking- comparing network performance using different FP tests running in parallel.

Network capacity evaluation- the buffer size feature combined with real-time measurements can help identifynetwork capacity issues or physical limits.

In this document the following aspects of FP testing, using the E6474A solution, are outlined and explained:

Features of the FP test

Parallel FP

Multiple file downloads and uploads

Passive versus Active mode

IPv4 and IPv6

Buffer size

Progress bar

Saving files to disc Measurements

Connection performance KPIs

Running and average/final throughput

E6474A FP versus DOS FP

Device binding

IPv6 addressing format

Frequently Asked Questions

Abstract

The FTP IPv4/IPv6 Test is

designed to meet your Drive Test

needs and accommodate the fast

evolution of wireless networks.

Find out how to best configure

your FTP test environment to get

the most accurate information

from your data network.


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Application Note: IPv4/IPv6 Testing Explained 2

FeaturesParallel FTPA unique feature of the JDSU FP test is its ability to run multipleinstances on more than one device in parallel. he FP test hasbeen designed to run network benchmarking using multipledevices each connected to a different network. o enable thisfeature all the network communication and FP protocol codehas been implemented without using any third-party or high levelAPIs. Both the data and control sockets are bound to the chosendevice. his ensures all traffic goes to the targeted interface such asmodems, wireless cards and network cards.

Multiple file download and uploadhe FP test supports multiple download and upload of files. Allfiles must be downloaded from, or uploaded to, the same folderdefined in the properties of the test. his differs from repeating asingle file FP test for two reasons:

Te connection to the remote FP server is kept openand only the data link is reopened. Tis has the benefit ofsimulating what the real user would do when downloadingor uploading multiple files.

Different files can be chosen for the same connection.

When selecting multiple files you can also define a pause betweeneach file which is uploaded or downloaded.

Passive versus Active modehe FP test supports both passive and active modes.

An FP client opens two sockets, one for remote communicationwith the server on POR 21 and one for data transfer. Once aconnection with the server is established the client will have thechoice between opening a data link either in passive or activemode.

Usingpassive modethe client opens the data link by connectingto the FP server on a random port, thus allowing the client tobypass the firewall if any is present.

Inactive modethe opposite occurs. he FP client is listening

on a random port and this time it is the server that will connect tothe client. If the client is behind a firewall, the connection requestfrom the server might be blocked.

If the FP test fails to connect while in active mode then it isrecommended you try using passive mode before investigatingother possible reasons for the test failure.

Passive mode is mostly used within a LAN network because mostfirewalls block incoming connections from unknown ports.

IPv4 and IPv6he FP test supports IPv4 and IPv6 protocols. his means youcan test IPv6 to IPv6 network and IPv4 to IPv4 network nodes byselecting the appropriate protocol in the FP IP Network ype

as shown below:

If you need to connect two IPv6 nodes over an IPv4 network,you must select the correct Automatic unnelling Pseudo (AP)interface for each device network interface. If the network is fullyIPv6, then it is possible to select the respective network cardsinstead of the AP interface and run FP tests in parallel. More

information on IPv6 networks is provided later in this applicationnote.


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he diagram below shows the different supported combinationsof IP interface:

Buffer sizeFP uses ransmission Control Protocol (CP) which is the mostcommon network protocol used on the Internet. Understandinghow CP operates can help you understand how to set the buffersize.

When GPRS networks were first established the FP test had adefault socket buffer size of 4 KBytes which reflected the relativelylow data rates of the early GPRS networks. his size is too small forfaster networks such as HSPA or WiMAX.

he table below shows the recommended buffer size for FP

PU, depending on the type of network used:Network Type Recommended Buffer Size

GPRS 4 KBytes

UMS & CDMA 64 KBytes

HSPA & WiMAX (Fast Data) 64 to 512 KBytes

TCP overview

CP uses a congestion window to decide how manypackets to send to the server at one time before looking for anacknowledgement. he bigger the congestion window, the higherthe throughput. he congestion window is directly related to thebuffer size.

o get the maximum throughput you need to have the optimalCP socket buffer size. If the buffer size is too small the CPcongestion window will also be too small and will not let enoughpackets through so the sender will be throttled.

If the buffer size is too large the sender client can overrun theserver with data. his will cause dropped packets and the CPcongestion window to close.

TCP buffer size

It is commonly agreed that the best buffer size is usually doublethe value for the packet delay multiplied by the bandwidth of thenetwork:

buffer size = 2 x delay x bandwidthSince twice the delay is the same as the round-trip time, you canuse the R: his value can be found using the PING command.

buffer size = RTT x bandwidth

his diagram shows that increasing the buffer size will increasefragmentation at the CP-IP layer, which results in more packetsbeing sent and acknowledged.

he CP buffer size can be set in the FP test properties.

he default FP buffer size is 64 KBytes. It is also the default buffersize of most FP clients.

As explained previously the buffer size will affect the performanceof CP. For instance, in case of FP upload, a buffer too large willincrease network congestion and the throughput will drop. On theother hand a buffer size too small will have the opposite effect andthe throughput will be consistent but low.

he following figure shows a FP upload running throughputline chart. he square shape shows periods of no activity dueto the socket being nonresponsive for too long. his is usually

Node A

IPv6 IPv6 Yes

Yes

Yes

No

No

IPv4

IPv4 IPv6IPv4

IPv4 IPv4IPv4

IPv6 IPv6IPv6

IPv6 IPv4IPv4 or IPv6

Node B SupportedNetwork Type

Automatic Tunnelling Pseudo Interface

Use Network IPv6 Interface card

E6474A FTP Client

File to be transferred

TCP-IP Stack Server

Packet 1

Packet 2

Packet N

send

ack

send

ack

send

ack

Socket

TCP Buffer

ACK

data

Block 1

Block 2

send

fragme

ntation


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an indication that the buffer is too large and that the network isoverloaded:

Ultimately the buffer size should be set appropriately for networkconditions to optimize throughput and minimize packetfragmentation and network congestion.

Progress barhe JDSU FP test has the ability to monitor the file transferprogress using the FP est Completed data item from the FPResults frame. By selecting this data item and adding it to a GridView and then configuring the properties of that data items todisplay the range of expected values you can generate a progress

bar for the FP test. Here are the values for this data item reportedduring an FP transaction.

0 = FP connecting to server

5 = FP connected

7 = User authenticated

10 = Data connection established

10 to 100 = File transfer progress

If there is a test failure, this data item can help to troubleshoot thetest by showing where to start looking for a problem.

For example if the test fails at the stage FP connecting to server(value = 0), check that you have the right server name and IP

address.

Similarly if the test fails at the stage User authentication (value =7), then check you have the right username and password enteredin the properties for the test.

Saving files to discWhen performing an FP download you can save files to disc byspecifying an output folder. Each test iteration will automaticallygenerate a sub-folder named as follows:

[output folder]\[test label]_[device name]_

[date and time]

For example: MyFiles\MyFPest_datadevice_25_8_2008_16_23_2_478

When more than one FP test is running in parallel ensure thateach test has an unique test name. his prevents the same outputfolder being used by different tests.

he downloaded file is saved inside the above sub-folder with anautomatically generated name with the following format:

[iteration number]_[file position in file

list]_[source file name].[source file name

extension]

Upload

Throughput

Time

Buffer size too large


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For example: 1_4_My10MEGFile.txt

Measurements

Time calculationMany different times are measured during FP transactions. Eachtime is measured in milliseconds.

his diagram represents a multi-file transfer using one FP test:

Optional pauses can be added to the FP test after the connectionhas been authenticated. For multi-file FP tests a different pausecan be added for each subsequent file transfer.

Throughput calculation

hroughputs are calculated at the application level. Some networkmonitoring tools (for example; NetPerSec) return slightly higherthroughput values. his is because they calculate throughputsat the IP network layer, which includes the CP header andretransmissions.

hroughputs are measured in Kilobits/sec (Kilo = 1024).

hroughputs are calculated in real-time every second. wo typesof throughput are provided:

Average throughput - he average or cumulative throughput isdefined as:p (Kilobits/sec) = Size of transfer (Kilobits) / ime for transfer(seconds)

Running throughput - he running throughput calculates theamount of data transferred in a one second period. It shows howmuch new data has been sent or received for each second elapsed.

E6474A FTP versus DOS FTPhe DOS FP is faster than any Windows FP tool due to itsextra access privileges. However, the JDSU FP can be as fast asthe DOS FP.

he main advantages of using the JDSU FP test over DOS FPare:

Produces real-time measurements and timers

Provides error reports

Supports multiple devices

he DOS FP only provides final measurements and doesnot allow device selection. he JDSU FP test provides moredetails about progress and errors. he JDSU FP test also usessynchronous socket mode which is also used by DOS FP.

A benchmark test was used to compare the DOS FP and E6474AFP tests. First five FP GE tests were run for both the DOS andE6474A FP tests in parallel. he tests used the same device andremote file from the same FP server. hen five FP PU testswere performed using the same conditions but this time usingsource files of the same size but with different file names to preventfile writing violations on the server.

R es pon se Tran sf er AuthenticationConnect Pause

Pause

DNS Resolution

Total Time

DNS Time Connect Time Authentication Time Response Time GET Time

R es pon se Tran sf er

Response Time GET Time

Total Time

First File

Second File


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he following table and charts outlines the results of thebenchmark tests.

DOS FTP E6474A FTP

Time TotalThroughput

Time TotalThroughput

Get 51.94 967.76 50.189 978.06

Put 25.92 1939.04 26.40 1858.90

Get 52.00 966.64 45.95 1068.18

Put 24.64 2039.84 25.76 1905.07

Get 99.42 505.60 99.11 495.28

Put 26.39 1904.64 25.11 1954.84

Get 99.21 506.72 98.86 496.53

Put 25.45 1974.80 26.17 1875.52

Get 88.42 568.48 88.72 553.28

Put 24.75 2030.96 24.47 2006.05

Device bindinghe JDSU FP test supports device binding which allowsmultiple FP tests to bind to different devices and run in parallel.Device binding is a two step process. he socket is first bound tothe assigned IP address of the device parent, with both IPv6 andIPv4 being supported.

A second binding occurs at the routing table level. Unfortunatelyin the Windows Operating System, the routing table supersedesthe socket binding. he routing table decides which device to usefor sending packets. o ensure data goes to the correct device aroute is added to the operating system routing table.

Note: Since IPv6 does not share the same routing table as IPv4 this

makes the bindings more complicated. However, E6474A FPdeals with those complications to make sure the communicationis bound to the correct device.

IPv6 addressing formatAs explained previously there are restrictions when using IPv6.Most of the Internet is IPv4 based and to support IPv6 networksdesigners have had to compromise on the network protocolstandards.

o reach an IPv6 host on a IPv4 network the Automaticunnelling Pseudo-Interface (AP) must be used. EffectivelyIPv6 in Windows XP and Windows Server 2003 use the

Automatic unnelling Pseudo-Interface for encapsulating IPv6packets with an IPv4 header so that they can be sent across anIPv4 network. By default, IPv6 configures a link-local Intra-SiteAutomatic unnel Addressing Protocol (ISAAP) address on theAutomatic unnelling Pseudo-Interface. he link-local ISAAPaddress has the form fe80::200:5efe:w.x.y.xorfe80::5efe:w.x.y.x,wherew.x.y.xis an IPv4 address assigned to the computer.

In the case of a multi-host machine capable of running parallelFP tests, it is necessary to check that each interface has arespective AP interface assigned. If this is not the case thenparallel testing will not be possible. Please check your networkconfiguration for more details.

If the network is fully IPv6 and all routers within the sub networkare IPv6 enabled then it should be possible to use the network cardinterface instead of the AP interface. his is adequate for parallelFP testing on different devices.

At present the E6474A application does not support IPv6 to IPv4FP. his requires Dual-Stack sockets which are only supportedby the Windows Vista operating system. Another alternativewould be the use of the IPv4-mapped IPv6 address format.Any IPv4 address must be represented in the IPv4-mappedIPv6 address format which enables an IPv6 only application tocommunicate with an IPv4 node. he IPv4-mapped IPv6 address

0

500

1000

1500

2000

2500

1 2 3 4 5

DOS Tp Uplink

E6474A Tp Uplink

0

200

400

600

800

1000

1200

1 2 3 4 5

DOS Tp Downlink

E6474A Tp Downlink


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format allows the IPv4 address of an IPv4 node to be representedas an IPv6 address. he IPv4 address is encoded into the low-order 32 bits of the IPv6 address, and the high-order 96 bits holdthe fixed prefix 0:0:0:0:0:FFFF. he IPv4-mapped IPv6 addressformat is specified in RFC 4291.

Here is the content of the RFC:

Frequently Asked Questions

Does increasing the buffer size impact FTP

download?Changing the buffer size for download has less impact than forupload. Most PCs can receive and store data faster than the FPserver can send data. hus a small buffer size can be as effectiveas a large one. However, a very large buffer size can be a wasteof memory and take up resources that can be used by otherprocesses running on your PC. JDSU recommends a buffer size of2000 KBytes for downloads.

Does increasing the buffer size impact FTP upload?Yes. Large buffer size will increase the risk of network congestion.

his means that the FP test sends more data than the networkcan cope with, resulting in packets being dropped and resent. Alsothe FP server bandwidth is shared amongst multiple users andcan be limited. he server might not be able to receive as fast as theFP client can send. It is possible to check packets dropped andother network information using the DOS commandnetstat s1.

Additionally using a line chart and monitoring the throughputyou will see the square stepped shape line indicating periods of lowthroughput as the network layer is overloaded and consequentlynot updating the layer above (FP application layer) fast enough.

If you believe your network can cope with a larger buffer sizes

but you still see throughput problems then check your networkreliability using the DOS command netstat s. Refer to thesection on Buffer size (page 3) for more information.

What is the recommended buffer size?It depends on the network used. he E6474A applicationuses a default value of 64 Kbytes. As mentioned earlier therecommended buffer sizes change depending on the networktype being used. For example, fast 3G and 4G networks benefit

1 Netstat is a DOS command-line tool that displays network connections

(both incoming and outgoing), routing tables, and network interfacestatistics.

from increasing the buffer size for FP download to a maximum(2000 KB) for an optimum performance.

Does increasing the operating system MTU improve

the FTP upload rate?MU (Maximum ransmission Unit), also referred to as packetsize, is the greatest amount of data that can be transferred in onephysical frame on the network. For Ethernet the MU is around1500 bytes, dial-up connections often use 576 bytes. A packetconsists of header and data information, the data is also referred toas MSS (Maximum Segment Size).

MU = MSS + CP/IP header

In theory increasing the MU will increase the transfer ratebecause larger packets are being sent, in reality this will work onlyif the network can support large packets. Increasing the MU willalso reduce the number of headers and routing decisions, as wellas client socket requests and device interrupts. here are someobvious benefits in manipulating the MU for large buffer size onfast networks such as WiMAX but JDSU does not recommenddoing this. he E6474A FP test does not support MUmanipulation. Changes to the MU can have a critical impact onyour system.

What is the best file size to use for an FTP test?here is no correct answer to this but it makes sense to considerthe expected data transfer rates on the network when choosingfile sizes. If you are testing UMS or HSPA technologies with veryhigh transfer rates, it does not (in general) make sense to choosea 200 Kilobytes test file. By the time the transfer has started, itis almost finished and the networking mechanics have hardlyhad a chance to get going. Conversely if you are testing GPRSwith a throughput of 48 Kilobits per second you will be waitingfor a long time to complete a download of a 1 megabyte file. It isrecommended to chose a file size that best exercises your network.

Why does IE FTP and DOS FTP work while the JDSU

FTP does not?Internet Explorer (IE), DOS and other windows-based FP

applications bind differently from the method used by the JDSUFP test.

he JDSU FP binds to an IP address specified in the deviceproperties so that the IP traffic is directed to the right networkadapter (dialup or network cards). Refer to the device bindingsection previously in this document.

he JDSU FP test binds using the selected interface IP addresswhile the windows-based FP tests use the default gateway whichis not always the same as the interface IP address.

he JDSU FP test might be blocked because the network maynot allow the specified interface IP address. his will result in a

80 bits

IPv6 Addressing Architecture

0000 .......................................................... 0000

32 bits16

FFFF IPv4 address


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Product specificationsand descriptions in this document subject to change without notice. 2010 JDS Uniphase Corporation 30168098 501 0111 DFPES.AN.NSD.M.AE Jan 2011

NORTH AMERICATEL: 1 866 228 3762

FAX: +1 301 353 9216

LATIN AMERICATEL: +1 954 688 5660

FAX: +1 954 345 4668

ASIA PACIFICTEL: +852 2892 0990

FAX: +852 2892 0770

EMEATEL: +49 7121 86 2222

FAX: +49 7121 86 1222

WEBSITE: www.jdsu.com/test

Winsock connection error.Check with your network administrator to confirm if thereare any blocked IP address groups which include your selectedinterface IP address.

What do these system error messages mean?

FTP error 425 Cant open data connectionhe data connection (for a directory listing, upload, or download)was unable to be established. Check your FP server settings tomake sure no ports are blocked. Also if your FP server is behinda firewall then check the firewall permission settings. Switchingto active mode might solve the problem assuming your clientmachine is not behind a firewall as well.

Winsock error 10053 The connection to the FTP

server failshe software caused a connection abort. his is usually caused bya connection time-out. o quickly check that your FP server isrunning and is reachable, run a traceroute test.

he connection could have been terminated by the server. heFP server logs can provide some clues about the exact reasonfor the failure. Check and verify that your ISP allows multipleFP sessions. Also, if a previous session failed for some reasonbut has not been killed off by the server, then the server may forcea disconnection of subsequent sessions until the broken session

times out.Finally, the error could be that you have a firewall configurationproblem which is causing the link to fail intermittently, in whichcase try using passive mode.

FTP Error 10057 Socket is not connectedA request to send or receive data was disallowed because thesocket is not connected and no address has been supplied.

FTP Error 10060 Connection timed outA connection attempt failed because the connected party didnot properly respond after a period of time, or the establishedconnection failed because the connected host server failed to

respond.

The connection to the FTP server was successful but

the FTP upload fails intermittently with FTP errors or

Winsock errors. What is the problem?

During drive testing it is common that the same file may beuploaded at the same time by different users. As a result somerequests would be rejected by the server because FP serversonly allow one upload of the same file at a time. his is similar toshared file systems. More than one user can simultaneously readfrom the same file (equivalent to FP download) but only oneuser can write to a file at a time (equivalent to FP upload). One

solution is to ensure that the file name is different on each machinepreventing file sharing violation on the server.

FTP IPv4 Error - Net Socket Errorhis IPv4 error occurs when the remote FP server is notresponding to connection attempts. his could be due to networkcongestion or the FP server not completely disconnecting fromthe previous session.

FTP IPv4 Error - System Format Errorhis IPv4 error occurs when the application can not parse thereply returned from the remote FP server. For example, theservers reply might include additional spaces between command

codes or the FP server welcome/warning message is too large tofit into single a internet packet and get phrased.

References And Additional InformationRFC 2581: CP Congestion Control

http://www.rfc-editor.org/rfc/rfc2581.txtRFC793 - ransmission Control Protocol

http://www.faqs.org/rfcs/rfc793.html

RFC959 - File ransfer Protocol

http://www.faqs.org/rfcs/rfc959.html

uning CP/IP for Performance

http://support.microsoft.com/kb/93444/en-us

MU, what difference does it make?

http://www.speedguide.net/read_articles.php?id=111

IPv6

http://technet.microsoft.com/en-us/network/bb530961.aspx

e6474a drive test tool ftp ipv4ipv6 testing explained

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