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MPT – GRE in UDP based Multipath Communication Library, User

1. INTEFACE The name of the interfac Go Sila In the example topology mentioned in Section 2 6 1 you should enable the physical interfaces after mpt srv is started ijere ime erail vg S o mprt int STAZ wS 4 3 mpt reload This command is used to notify the MPT server that the configuration was changed and needs to be reloaded If we do not specify any arguments the server will read all connection configuration files from the conf connections directory having conf extension The server will detect whether the connection is new or changed in some parameters We are not able to delete a connection with the mpt reload command the mpt delete must be used for that A file name can be specified as an argument in order to reload only that file and ignore changes in others The file name must be given without path For example 13 mpt reload connection conf 4 4 mpt delete To remove a connection we can use the mpt delete command It requires an argument which is the file name without path containing the connection to be removed For example S mpt delete connection conf This command removes all connections described in the connection conf file so we highly recommend to have only one connection in each configuration file The configuration file will not be deleted permanently but will be renamed to conf disabled to prevent them from being loaded next time 4 5 mpt save The current configuration
2. can be changed during runtime by remote peers This can be enabled as mentioned in Section 2 6 2 with the accept_ remote key and in Section 2 6 3 1 with the permission key This command is used to write these connection changes to the configuration files so the new settings will remain after server startup or after mot reload The usage of this command can be viewed in mpt help mpt save FILENAME FILENAME Save changed connection information to config file Optional The mpt save command can be called without arguments in this case all changes will be written If the file name is specified without path then only changes related to the connections described in that file will be written 14 Appendix A List of figures Figure 1 The MPT layered architecture ysis lt cecssssuccssdesevenvasseacceitcosecisavucesaladetsscavnceves Figure 2 The PDU structure of the MPT based communication cceseeeeseeeeees Figure 3 A sample topolo Sy occicca c ssssed asad oaecauheg act doscnanch nebo eaete ea ensaas eae Appendix B List of tables oA AD be coll Mea ALLS as srcsaiet atic sccm gt seat tos eed ace age a ane dad E capa du aaa ncaa Table 2 Connection update snoin onin aia ones Auten E edeen Mia eens Antec Table 3 Authentication TY PeSwasiss tial ests tee Mice asaaca haces ten ous mde tenner yerves tues Appendix C List of configurations Configuration 1 A sample interface conf
3. connection is used to refer to the communication session or probably independent communication sessions between two end hosts The term path is used to refer to the pair of the network cards of the end nodes identified by the pair of the cards IP addresses Using a specified path the packet transmission runs between the given pair of network cards To put it simply the multipath environment means that one connection is able to use multiple paths multiple pair of IP addresses for packet transmission The IETF RFC 6824 TCP Extensions for Multipath Operation with Multiple Addresses MPTCP published in January of 2013 describes the necessary extensions for the TCP protocol in order to extend the current TCP implementations for supporting multiple paths Actually the MPTCP works in the transport layer and is restricted to the TCP protocol Application Tunnel TCP UDP Tunnel IPv4 IPv6 Tunnel GRE in UDP UDP Physical UDP Physical IPv4 IPv6 Physical IPv4 IPv6 Physical Network Access Network Access Figure 1 The MPT layered architecture The purpose of the MPT library is to open the possibility for the multipath environment in the network layer The architecture of the MPT communication environment is based on the IETF RFC Draft GRE in UDP specification which is currently a work in progress state specification but the MPT environment allows the usage of
4. device 2 Jeev Mote tuia Tunnel file desc 4 Tunnel ipv4 addr 10 0 0 2 24 Tunnel ipv6 addr fec0 2 64 CMD server port number 60456 CMD client port number 52242 Global server 2 If the start was not successful e g root privileges are missing an error message will be given for example Tunnel interface IOCTL error Errno 77 After the MPT server started we can check in other terminal windows whether the tunnel interface was successfully created ip addr EEE 5 tun0 lt POINTOPOINT MULTICAST NOARP UP LOWER _UP gt mtu 1452 qdisc pfifo fast state UNKNOWN glen 1500 link none inet 10 0 0 2 24 scope global tun0 imete fec0 2 64 scope site Wale lire COrever Preretred line COrewer After closing the MPT server the IP settings of physical interfaces will not change back only the tunnel interface will disappear If we start the server again we can calmly ignore this error message RTNETLINK answers File exists 4 Sending commands to the server There is a client application called mpt which can send commands to the server on the local machine to control its working behavior at runtime Running the mpt client without parameters a brief syntax description will be printed including the available commands Seer mote Usage mpt 6 port_number mpt_command mpt_args 6 Use IPv6 to communicate with mptsrv Porc imbmMISSic The jOowie Aumoer Cue clas mocsiw dereavults 5010
5. public _ipaddr 10 2 252 gw_ipaddr 10 252 52 remote ipaddr 105 2 2538 keepalive tim 5 dead_ time 11 window size 1 status 0 HHHHTEEEEHEHEEEE REET NETWORKS HAA tt EE AE AE EE HH HEE EE HH HEE EH EH EH EE mast 0 1o ver 4 src_addr Lil dst_addr 21 Maer 1 ip Ver 4 Sre acle 12 dst_addr 22 PR j 0 24 0 24 0 24 0 24 Configuration 2 A sample connection conf file 2 6 3 1 General connection configuration section connection The connection section contains the general description of a connection Here is the list of the keys of the connection section name mandatory The value is a word without space containing the unique name of the connection If we use multiple connections the name must uniquely identify the connection permission mandatory The permission key may have four possible values depending on what we want to permit to the program There are SEND and RECEIVE permissions which allow sending and receiving connection updates The term SEND means that the local MPT environment is allowed to start configuration change to the peer The term RECEIVE means that the peer is allowed to start a configuration change and the local MPT environment will accept it The interpretation of the values can be seen in Table 2 RECEIVE SEND VALUE 0 1 2 3 Table 2 Connection update ip_ver manda
6. settings e g interface addresses route table entries The content of these command scripts can be changed without recompiling the source In the conf directory there are the configuration files see Section 2 6 In the doc directory the documentation that belongs to the selected package can be found The src directory contains the source code It is beyond the scope of this document to explain this in detail please read the Developer Manual for further description 2 6 Editing the configuration files 2 6 1 Design topology We will need the local and remote IP addresses of the MPT environment endpoints and we will need to allocate two new IP addresses for the tunnel interface Now a sample configuration with two paths will be discussed Figure 3 shows the IP address and port number assignments in this example ethl ethl 10 1 1 2 2345 tun0d tunO0 W10 1 1 3 23456 n 10 0 0 2 Tunnel 10 0 0 3 amp CMD 6045 eth2 eth2 10 2 2 2 23456 10 2 2 3 23456 Figure 3 A sample topology This document discusses the configuration files on host A but the package files contain the configuration files for host A and host B too In the studied example we assume that the Ethernet cards of the hosts are directly connected to each other i e eth1 ofhost A is directly connected to eth1 ofhost B and eth2 ofhost A is directly connected to eth2 of host B 2 6 2 The interface conf file The tunnel interface and some general co
7. MPT GRE in UDP based Multipath Communication Library User Guide 2015 09 03 Project leader and main contact dr B la Alm si almasi bela inf unideb hu Faculty of Informatics University of Debrecen Debrecen Hungary Developers and members dr Mark Kosa Ferenc Fejes Robert Katona Tamas Kelemen Levente P s k Table of contents Introduction esinen iaa a e Ea ea E a E Ea E Ea 2 2 Using th MPT pProjeCtiecninien na n OES 3 2 1 Getting the latest CiStribUtiOM iccs cacssensesssneanccessscsencananseeteventeceesersceesneets 3 2 2 Installing Aepend Sn cies ack acesnocescuss yi vasdsdssa selon Gpeasnicuseadessanacdonaee 4 2 3 Extracting the tarballg o csexsiovesusssennastunossendstiasdsaistuetastsuaveseveinuaneseesndseeawaee 4 2 44 Compiling the source code ssseseeseesessseesseserssesseseessressessrssressessessees 4 2 5 The directory structure of the MPT environment ceeeeeeeeeeeeees 4 2 6 Editing the configuration files gccercssasosavensienesdsonincascenusdsxnincnssntiawancsounioee 5 200 1 Design topologisen eni e AE EEEE 5 2 6 2 The interface Conf PIG scvasecenstencsucdustantarsseanuncteneteseseaniae 6 2 6 3 ce 056101 Meret eee ne ee ne nee nee ne oer ee eee 6 2 6 3 1 General CONMSUTATIONG jscessiesdeiasctacisionaesensncniarotaaninasban 7 2063 2 PALS scesaeysa viet iuawncssnsilnntaeansnsnsasnesieatsnbanesaneanpantantsteinnbieaseupentiennards 9 2 6 3 3 DUC OTIS cer sracetenndsceeecssnceiencesea
8. Revere In the following sections the commands of the MPT client will be discussed 12 4 1 mpt address This command can be used to add new IP addresses to an interface or remove an existing one A brief description about the usage of this command can be shown by typing mpt address without arguments mpt address mpt addi less add del IP_ADDRESS PREF_LEN dev INTERFACE IP ADDRESS The IP address can be v4 or v6 to manipulate PREF LEN The prefix length of the manipulated address Default prefix length 24 for IPv4 64 for IPv6 INTERFACE The name of the interface related to the manipulated address As it can be seen in the description we can shorten the word address as addr There is only two useable operators for this command add and de1 for delete The IP address can be given without prefix length or with a prefix length after it separated by a sign It is automatically detected whether the address is IPv4 or IPv6 If the prefix length is not specified the default value will be used which is 24 for IPv4 and 64 for IPv6 4 2 mpt interface With this command we can enable or disable an interface A brief description about the usage of this command can be printed by typing mpt interface without arguments We can shorten the word interface as int Its usage is very simple mpt interface mot int erface INTEFACE up down
9. ave to mention that the fields of Tunnel IP and IP are absolutely independent which means that also the IP versions can be different it is possible to use IPv6 for the application 1 e Tunnel IP will be IPv6 and to use IPv4 for the network interface i e IP will be IPv4 in this case Also it is possible for the application to use IPv4 1 e Tunnel IP will be IPv4 and use IPv6 for the network interface i e TP will be IPv6 Of course the two versions can be the same To use the MPT multipath communication environment we have to configure and start the MPT server see the next chapters of this document and we have to use the tunnel interface for the application s communication on both endpoints 2 Using the MPT project 2 1 Getting the latest distribution To get the MPT environment please contact the e mail address almasi bela inf unideb hu The MPT software library was written in C in Linux The project is delivered in various packages as described in Table 1 A package can contain the documentation source code and precompiled binaries The mpt gre 1lib32 and mpt gre 1lib64 library packages were developed for Intel 386 and AMD x86 64 architectures These distributions contain the user guide the header files the source code of the main program of the MPT server and the compiled library files Libmpt a cli a which can be used to create the server mptsrv and the client command line
10. ecernteeneereceatunaarencnsneeeee tence 11 Running the MPT SErVel sss eiiener nini aaa R E 12 4 Sending commands to the server ivdcisecssiarvcovesasasssesseddocsussvostsveavervesdareseciasyes 12 4l pt addres Suys i ea A aan esa 13 42 mpte Interf aCeee cw en reen EA EE EREEREER 13 43 mpe relo d eerren aer aeaaeae EEA EERE EEA ERASE 13 44 mpt eo AEC cig nc eRe Re Ee TRE Cen a a a reer er 14 cos MOE SAVO ee eee E 14 1 Introduction The current Internet communication environment allows the usage of a single path only for data transmission in a communication session the endpoint of a communication session is identified by the IP address of the host s interface and the port number is also used inside the host for the identification The single path assumption is quite acceptable for systems which use a single connection interface or a single exit point to the Internet On the other hand a lot of currently used devices have got factory built in multiple network interfaces RJ 45 for the wired network RF interface for the Wi Fi wireless network connection and mobile phone data transfer connection interface e g 3G LTE or HSPA The single path communication technology is not able to use the advantages of the multiple available interfaces The communication performance e g throughput reliability could be highly improved if the networking environment supported the usage of multiple paths inside a communication session The term
11. elay msec specifies the maximum time in milliseconds while the packet is stored in the buffer array If the packet is delayed in the buffer array for the specified time it will be transmitted to the tunnel interface even in the case when some packets are missing before the considered packet The missing packets are considered as lost packets i e we will not wait more for a lost packet The arrived packets are transferred to the tunnel interface according to their GRE sequence number so the ordered delivery will be kept also in the case of packet loss auth_type mandatory The MPT system uses control communication between the tunnel endpoint The control communication can be requested to use authentication The value 0 means no authentication Other useable values can be found in Table 3 auth_key optional The auth_key contains the key value of the control communication authentication Some algorithms do not need authentication keys In this case the specification of the auth_key is not necessary or will be ignored The list of authentication algorithms and their keys required can be found in Table 3 AUTH TYPE AUTH KEY Algorithm name 0 No AUTH _NONE 1 No AUTH_ RAND 2 Yes 64 byte long in HEX AUTH _SHA256 Table 3 Authentication types 2 6 3 2 Path configuration sections path_n interface name mandatory The value is the name of the physical interface used by the given path for packet forwardi
12. es several seconds as the server must communicate the action to its peer The section tun _0 describes the tunnel interface parameters The name key specifies the name of the tunnel interface which is used by the operating system to access to the interface The ipv4_ addr andthe ipv6 addr parameters set the IPv4 and IPv6 address and prefix length of the tunnel interface The tunnel interface is created and configured by the mpt srv application automatically no further interaction is required from the user 2 6 3 Connections Connection configurations can be found in the conf connections directory and must have conf extension An example configuration is shown in Configuration 2 based on the topology shown in Figure 3 HHHHEEHEHHEEEEEEEEEEEE HEHEHE GENERAL INFORMATION HH EEEPEHHEEEE connection name MPN Commacredem 10 0 0 2 permission 3 1o Wee 4 ij loea LO 0 052 local_port 23456 ip Emote 1000S remote port 23456 remote cmd port 60456 path_count 2 network count 2 status 0 reorder window 0 max _buffdelay msec 200 auth type 0 auth_key 0 HHEHHEEEEERREEREEEEEEEEEEE PATHS AARE TEA AE TE AE AE HAE EEE EERE EE HH EE HEHE path _0 interface nam thl 1o yer 4 public _ipaddr A uli Rolin 2 gw_ipaddr NOs Ihe al a remote ipaddr 101 1538 keepalive tim 3 deacli time 11 window size il status 0 path 1 interface nam Tella 1D Wie 4
13. fle weiss cccccesdatissceencdtecesdvasidameseeeies Configuration 2 A sample connection conf file seesseseesessesersesseesesseseesesse 15
14. i e not only the tunnel peers can use the tunnel for communication The value must be chosen from the interval 0 20 This key is an integer denoting the number of networks on which the actual connection is able to route This configuration file must have sections net_n where 0 lt n lt l describing all networks that belong to the connection status mandatory The key indicates the initial status of the connection The value 0 means OK reorder window optional The MPT environment can be forced to ensure the right ordered packet transmission for the tunnel communication As the delay of the different paths can be different packet reordering may appear in a packet sequence transmission In this case the receiver uses a buffer array to store the incoming unordered packets Then the packets are sorted according to the GRE sequence numbers so ensuring the ordered transmission to the receiver s tunnel interface The reorder window value specifies the length or size of the buffer array The value of 0 which is the default value when omitted the key means that no sorting will be performed at the receiver the packets are transferred to the tunnel interface immediately when they arrive The maximum value of the reorder window parameter can be 10 000 max_buffdelay msec optional This key is used only if we require ordered packet transmission i e reorder window gt 0 If ordered packet transmission is required max buffd
15. interface mpt executable A simple example configuration is also given in the mpt gre 1ib32 and mpt gre 1lib64 distributions The mpt gre src package contains the source code including the libraries sources the user guide the developer s documentation and the compiled libraries File name Docs Sre Compiled Executable library mpt gre src Y Y Y Y MM DD tar gz Yes Yes Yes No mpt gre lib32 Y Y Y Y MM DD tar gz Yes No Yes Yes mpt gre lib64 Y Y Y Y MM DD tar gz Yes No Yes Yes Table 1 Tarballs 2 2 Installing dependencies The MPT server needs libe GNU C Library including pthread make gcc iproute openssl tar and gzip packages to be installed The package names and its installation method can be different on the various Linux distributions and architectures On Debian based distributions it can be installed with apt get install libc6 dev make gcc gcc multilib libssl dev iproute Tene Gao On Intel 386 and AMD x86 64 architectures the package names may have different suffixes e g for the Intel 386 architecture this suffix is 1386 and for AMD x86 64 architecture this suffix is amd 2 3 Extracting the tarballs The package file contains a complete file structure under a subdirectory called mpt which needs to be extracted We recommend to put this folder into the opt directory To do that use this command S rene AVAE PACKAGE FILENAME C Jopt G cd opt m
16. multiple paths see Figure 1 In this architecture we distinguish the identification of the communication session s endpoint application s socket and the physical communication interface In this mechanism we create a logical tunnel interface on the endpoints which can be used by the applications for the socket identification The IP packets transmitted to the tunnel interface by the application are encapsulated by the MPT software into a new GRE in UDP segment which will be sent to the physical network interface for transmission The MPT server or MPT library offers the possibility to map the packets coming from the tunnel interface to multiple physical interfaces dynamically so offering the multipath communication for the application There is no need to modify the application s software in this case as the application software uses only one single logical interface the tunnel interface for the communication Also the application may use the UDP transport protocol over the tunnel interface it is not restricted to the TCP protocol On the other hand as the MPT library uses the UDP protocol in the encapsulation process it will not offer retransmission and flow control services below the tunnel interface IP UDP GRE Application v4 orv6 Fixed port TCP UDP data Figure 2 The PDU structure of the MPT based communication The structure of the packet transmitted by the MPT environment can be seen in Figure 2 We h
17. nfiguration setting can be found in the conf interface conf file The configuration file is a standard ini file Each line has a key and a value part The name of the key indicates its functionality The value is assigned to the key by using the equality sign 66 59 Comment lines start with a sign general tunnel num S Accept remote new connection request QCCESE_icemoces 1 cmipor mocami ESOS cmd timeout 25 tun_0 name tun0 ipv4_addr 10 0 0 2 24 ipv6_addr fec0 2 64 Configuration 1 A sample interface conf file The file is made up of sections The first section contains general information Here we configure how many tunnel and interface we want to handle by using the mpt software The current version of mpt handles one tunnel interface which must be declared In the general section the accept remote key indicates weather the software enables mpt srv to act like a server If this parameter is set to 1 then clients can initiate creating new connections not defined in local configuration files The server will accept control commands from remote sites clients The cmdport local parameter sets the UDP port number which will be used to accept control commands The cmd_timeout parameter sets the timeout value in seconds of the local client waiting for the server s answer i e the mpt command will wait cmd_timeout seconds for the answer of the server Usually the server action tak
18. ng e g wlan0 ip _ver mandatory Specifies the version of IP used by the path The value can be 4 or 6 public ipaddr mandatory Specifies the public IP address of the interface used for the tunnel communication If the host is placed into the Global Address Realm the public _ipaddr is the IP address of the interface otherwise i e when the host is behind a NAT Box it is the public address assigned by the NAT Box to the tunnel communication session If the path uses IPv4 and NAT then the special address value of 0 0 0 0 can be used to force the mptsrv program to determine the public IP address automatically private _ipaddr optional The IP address of the physical interface Can be omitted ifthe public ipaddr is assigned directly to the interface When using IPv4 and NAT the special value of 0 0 0 0 can be used to force the mpt srv application to read and use the first IPv4 address assigned to the interface remote _ipaddr mandatory Indicates the public IP addresses of the remote endpoint gateway ipaddr mandatory The IP address of the gateway used to reach the peer i e remote ipaddr using the given path keepalive_time optional The MPT system monitors the availability of each path by sending keepalive messages regularly The key specifies the frequency ie the time between the keepalive messages in seconds that mpt s rv uses for sending keepalives The value of zero which is the default value means
19. nnection 11 1 1 0 24 21 1 1 0 24 12 1 1 0 24 22 1 1 0 24 Figure 4 A sample topology for networks HTH H HHH HHT Ht tata aa NETWORKS FEA att at it AE it it AE it FE at FE FE FE FE FE FE FE FE FE aE FE PP E E E E E ner 1D _ were 4 SicC_aclele 11 1 1 0 24 dst_addr 21 1 1 0 24 mere 1 io ver 4 SicC_aclcle 12 151 0 24 dst_addr 22 1 1 0 24 Configuration 3 The network part of a configuration file 29 Every section that belongs to a network configuration start with the net __ prefix In these sections the ip ver key indicates the version of IP protocol used by the network The src_addr describes the source network and its prefix length Similarly the dst addr key describes the destination network and its prefix length With these parameters we are able to define a route between networks through the defined connection i e we can establish a multipath connection between sites The network configuration can also be used to provide multipath Internet connection by specifying 0 0 0 0 0 as destination address and prefix length The source is our tunnel address in this case 11 3 Running the MPT server For starting the MPT server root privileges are necessary To obtain root privileges the sudo command can be used To start the server just type in mptsrv On successful startup the output will be something like this Tunnel information Tunnel interface tun0O Tunnel
20. pt 2 4 Compiling the source code On Intel 386 and AMD x86 64 architectures the mpt and mptsrv can be rebuilt with the help of the precompiled libraries 1ibmpt a and cli a which can be found in mpt gre 1lib32 and mpt gre 1ib64 library packages For this you can use the following command S make You can build both 32 bit and 64 bit version of the programs depending on the library package used you have to use the mpt gre 1ib32 package or the mpt gre lib64 package respectively You have to be very careful when using these libraries because they use the m32 and m64 compiler options which are only valid on Intel 386 and AMD x86 64 architectures If you would like to build the server and the client program for other architectures then you have to use the full source package This package contains a Makefile that does not use m32 and m64 compiler options for building the programs 2 5 The directory structure of the MPT environment Everything can be found in the mpt folder every file and folder mentioned later is relative to that The binaries can be found in the root of the mpt folder There is a server application called mpt srv and a client called mpt see Chapter 3 and Chapter 4 The client application i e the mpt command can be used to modify the server working parameters e g turn off or on a path usage in the system In the bin directory there are some scripts that are used by the MPT server to configure system
21. switching off the keepalive mechanism dead_time optional If the keepalive mechanism is active and the host does not receive keepalive message on the given path from the peer for dead_time seconds then the path is considered as dead and will not be used for data transmission The default value is 3 keepalive time weight out mandatory This is the weight of the path in the system The mptsrv program distributes the outgoing packets between the available paths according to their weighs For example if we have 3 paths with weights 12 18 15 then the sending cycle contains 45 packets the sum of the weights In each sending cycle each path will transmit packets according to the weight value In our example the first path will transmit 12 packets the second path will transmit 18 and the third one will transmit 15 packets in one sending cycle The sequence of the paths in a sending cycle is optimized to perform the best approximation to the ratio of the weights at each timepoint inside a sending cycle status mandatory This key means the initial state of the path after starting mptsrv The value 0 means that the path is usable working and the state of the path is OK 10 2 6 3 3 Network configuration section net_n With configured networks in mptsrv we are able to use the application as a router routing the packets among several networks between the tunnel endpoint establishing a multipath site to site co
22. tory The key indicate the local and remote IP version of the connection i e the IP version used by the tunnel interface It can be either 4 or 6 ip_local mandatory The IP address of the tunnel interface local_port mandatory A number between 1 and 65534 It refers to the GRE in UDP data port which is not fixed yet by IANA It must be an unused UDP port number It is going to be used for sending and receiving data packets on any path If it is not a unique unused port the server will be unable to bind and will exit immediately ip_remote mandatory The IP address of the tunnel interface of the remote peer remote_port mandatory Similar to 1ocal_port but it is used on the remote peer It is going to be used as a target UDP port when sending data through the tunnel to the peer remote_cmd port mandatory The UDP port number of the peer which is used to accept control commands If we start an mpt command e g turning offa path usage the mptsrv server will communicate this action to the peer by using its remote _ cmd port as the destination port number path_count mandatory The key is an integer p denoting the number of paths defined for this connection The minimum value is 1 the maximum value is 20 This configuration file must have p sections path n where 0 lt n lt p describing all paths of the connection E network_count mandatory The MPT environment can be used to establish tunnel between networks

MPT – GRE in UDP based Multipath Communication Library, User

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MPT &ndash; GRE in UDP based Multipath Communication Library, User

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MPT – GRE in UDP based Multipath Communication Library, User