User`s Manual for the SCPS Reference Implementation
Contents
1. Working Note WN 97W0000026 April 1997 27 Appendix A Manual Page for scps_init Application SCPS_INIT 1 NAME scps_init sample SCPS based client program SYNOPSIS scps_init A b size B C D G L M R rate S T Z host DESCRIPTION Scps_init is a sample of a SCPS based client program Scps_ttcp allows the user to set various SCPS options via the command line OPTIONS A ackdelay Set the value of the maximum time in milliseconds a SCPS TP entity must send a TP acknowledgment b size Set size of socket buffer in bytes B Enable SCPS Best Effort Transport Service BETS operation if supported by the peer C Enable SCPS compression operation is supported by the peer D Don t buffer SCPS TP writes sets SCPS NODELAY option G Enable TCP Vegas Congestion control algorithm L Set SCPS socket to non blocking mode M mtu Sets the Maximum Transmission Unit MTU in bytes for this connection R rate Sets the SCPS rate control value in bps 29 Disables SCPS Selective Negative Acknowledgment SNACK Disables SCPS TimeStamp operation Enable SCPS BETS SCPS compression SCPS SNACK and SCPS TimeStamp options 30 Appendix B Manual Page for scps_resp Application SCPS_RESP 1 NAME scps_resp Sample SCPS based server program SYNOPSIS scps_resp A b size B C D G L M R rate S T Z DESCRIPTION Scps_resp is a sample of a SCPS based client2. Port number to send to or listen on default 2000 On some systems this port may be allocated to another network daemon Set the value of the maximum time in milliseconds a SCPS TP entity must send a TP acknowledgment If transmitting using TCP do not buffer data when sending sets the TCP_NODELAY socket option When receiving data output only full blocks using the block size specified by l This option is useful for programs such as tar 1 that require complete blocks Align the start of buffers to this modulus default 16384 Align the start of buffers to this offset default 0 For example A8192 O1 causes buffers to start at the second byte of an 8192 byte page Specify using one of the following characters the format of the throughput rates as kilobits sec k kilobytes sec K megabits sec m megabytes sec M gigabits sec g or gigabytes sec G The default is K Touch the data as they are read in order to measure cache effects 34 G F M m mtu R rate Verbose print more statistics Debug set the SO_DEBUG socket option Enable SCPS Best Effort Transport Service BETS operation if supported by the peer Enable SCPS compression operation is supported by the peer Override the default Congestion Control Algorithm 0 Disable Congestion Control 1 Van Jacobson Congestion Control 2 TCP Vegas Congestion Control Set default ACK behavior 0 Strictly
3. the result of each of these decisions is passed to the configuration command script as parameters The configuration command script will use a default value for any parameter that is not supplied To invoke the configuration command script and accept all of the default values for parameters one would change directory to the FP subdirectory under the SCPS directory and execute the command configure Continuing our example of using a Sun Sparc workstation the response to the configure command with default values for all parameters is as follows configure 13 Configuring make file for sparc sun sunos4 1 3_Ul Created Makefile system sunos size small debug off Using TP sockets In order to specify a non default value for the size of the SCPS FP implementation the user should specify the following command line parameter to the configure utility where specified_size is replace by either small medium or large size specified_size To explicitly specify the transport protocol over which the SCPS FP should operate the user should supply the tp parameter to the configure utility specifying yes to use the SCPS stack as the lower layer service and specifying no to use the in kernel TCP IP stack as the lower layer service To specify whether debugging information is enabled or disabled the user should supply the debug parameter with yes or no respectively Here is an examp
4. and Space Administration NASA and the Department of Defense DOD that is chartered with producing a set of specifications for standardized end to end space mission data transfer covering the following technical areas 1 An efficient file handling protocol the SCPS File Protocol or SCPS FP optimized towards the up loading of spacecraft commands and software and the downloading of collections of observational telemetry data 2 Various flavors of underlying retransmission control protocol the SCPS Transport Protocol or SCPS TP optimized to provide reliable end to end delivery of spacecraft command and telemetry messages between computers that are communicating over a network containing one or more unreliable space data transmission paths 3 A data protection mechanism the SCPS Security Protocol or SCPS SP which assures the end to end security and integrity of such message exchange 4 A scaleable networking protocol the SCPS Network Protocol or SCPS NP that supports both connectionless and connection oriented routing of these messages through networks containing multiple space data links 1 2 The SCPS Reference Implementation As part of the standards development process implementations of each protocol have been developed These protocol implementations have been integrated together for distribution as the Reference Implementation of the SCPS protocols This Reference Implementation is being made available for the purpose of ev
5. the build of SCPS TP Users may issue socket options to change the behavior from its default Refer to the SCPS TP User s Guide for more details TCP standard congestion control RFC 1323 window scaling RFC 1323 TCP timestamps Increased initial congestion window Combined SCPS negotiation option Selective Negative Acknowledgment SCPS Header Compression Best Effort Transport Service Multiple Forward Transmissions Note that the Makefile is overwritten by an execution of the configure utility If changes to the SCPS_TP variable in the Makefile are made but not also made in the Makefile template Makefile in these changes will be lost when the configure utility is next used in the source directory 2 4 Building the Reference Implementation The UNIX command make is acommonly used method of simplifying the maintenance of programs After the individual directories have been properly configured as described in section 2 3 return to the SCPS top level directory and type make The SCPS Reference Implementation will build the SCPS library the SCPS FP and all of the example SCPS applications The SCPS FP executable files and the example applications will be copied to the bin directory The SCPS library will be copied to the lib directory 16 2 5 Tcpdump The SCPS Reference Implementation provides a simple method of extending tcpdump to understand the SCPS lower layer protocols A copy of tcpdump version 3 4a5 avai
6. 14 2 4 Building the Reference Implementation 16 2 5 Tcpdump 17 Using SCPS 19 3 1 Configuring SCPS 19 3 1 1 Configuring the SCPS Routing Table 19 3 1 2 Configuring the SCPS Address Mapping Table 19 3 1 3 Configuring the SCPS Security Requirements 19 3 2 Using SCPS Protocol Services 20 3 3 Developing Applications using the SCPS Library 20 3 4 SCPS Application Examples 21 Section 3 4 1 SCPS Server 3 4 2 SCPS Client 3 5 SCPS Utilities 3 5 1 SCPS ttcp Feedback List of References Appendix A Appendix B Appendix C Appendix D Appendix E Glossary Manual Page for scps_init Application Manual Page for scps_resp Application Manual Page for scps_ttcp Application List of Files in Reference Implementation Distribution Problem Report Form vi Page 21 22 22 22 25 27 29 31 33 37 43 45 Section 1 Introduction This section provides a basic background on the SCPS project and the SCPS software release 1 1 What is SCPS The Space Communications Protocol Standards SCPS project has been jointly established by NASA and DOD to recommend and develop standard space data communications protocols It is the task of the SCPS project to specify integrated layered stacks of standards and their options that can satisfy common requirements of both the military and civil space user communities of the United States Every effort is being made to converge on common solutions to common problems so that a wide range of op
7. 3 DINIT_CWND_INCR Enable initial congestion window of up to 4380 bytes refer to J C Hoe ACM SIGCOMM 96 Improving the Start up Behavior of a Congestion Control Scheme for TCP DOPT_SCPS Enable combined negotiation of SNACK header compression record boundaries and BETS via a single connection time option DOPT_SNACKI Enable SCPS selective negative acknowledgment option DOPT_COMPRESS Enable SCPS header compression DOPT_RECORD_BOUNDARY Enable record boundaries on SOCK_SEQPACKET sockets DOPT_BETS Enable Best Effort Transmission Service a partial reliability TCP service DMFX_TRANS Enable multiple forward transmissions mutually exclusive with all congestion control schemes By default the SCPS_TP constant is defined in the Makefile as the following string SCPS_TP DOPT_SCALE DOPT_SNACK1 DOPT_BETS DOPT_TSTMP DOPT_COMPRESS DCONGEST DVJ_CONGEST DOPT_SCPS DINIT_CWND_INCR DOPT_RECORD_BOUNDARY Note that the back slash V at the end of the first line indicates a continuation of that line and should not be deleted Users should bear in mind that specifying these options only makes them available for use If a particular capability described above is included in the build of SCPS TP the use of that capability may be enabled or disabled on a per connection basis The following table describes 15 the default behavior when that capability is included in
8. BSD and the Silicon Graphics IRIX operating environments The SCPS Reference Implementation uses its own thread scheduler to achieve a limited multitasking capability within a single Unix process This particular approach was selected because POSIX threads were not and still are not as widely supported as necessary and because some operating platforms e g spacecraft had no real operating system services at all The impact of this decision on portability is that there is some embedded assembly language code in the file thread c This assembly language code saves and restores the stack frame and the machine registers during task context switches The assembly language code is embedded using the GNU C compiler style for embedding assembly code and therefore the SCPS Reference Implementation depends on the availability of the GNU C compiler In addition users wishing to port the SCPS Reference Implementation beyond the following hardware architectures will need to add a small amount of assembly language to the function threadHandoffCPU in the file thread c e Sun Sparc instruction set architecture e Motorola M680X0 instruction set architecture e Intel 80X86 instruction set architecture e MIPS 3000 instruction set architecture Note that this assembly language has also been generated for the MIL STD 1750 processor but is not distributed with the SCPS Reference Implementation Users interested in this code should contact the
9. IP interface To use the Raw IP interface the SCPS Reference Implementation process must be run at superuser privilege Users have a choice of two network layer protocols when using the SCPS Reference Implementation IP or the SCPS NP When using the SCPS NP the Reference Implementation always encapsulates the SCPS NP packets in either Raw IP or in UDP IP This permits routing of the SCPS NP packets through the Internet In an operational environment users may choose to retain this encapsulation in ground networks and strip the encapsulating IP or UDP IP headers at the point of entry into the wireless network segment When using IP as the network layer protocol the IP packets may either be routed directly or like SCPS NP packets may be encapsulated in another IP header This could be useful when the IP address of the point of entry into the wireless network segment is known The outer packet would carry the IP address of the wireless entry point and the inner packet would carry the IP address of the destination As with SCPS NP packets IP packets may also be encapsulated in UDP IP headers For both IP and the SCPS NP the UDP IP approach is necessary if the user wishes to test in loopback mode on a single machine The following table summarizes the alternatives for configuring lower layer services Network Layer Protocol In Use Lower Layer Service Options Direct operation over Ethernet IP in IP encapsulation IP in UDP IP
10. PS Reference Implementation has been developed with the philosophy that only the specific SCPS lower layer services required by a particular application should be incorporated the build that supports that application To realize this the SCPS Reference Implementation allows users to customize the SCPS library to include only the protocols and options within those protocols which are required The SCPS TP forms the basis of the SCPS library the SCPS SP may be included or not and the network layer protocol may either be SCPS NP or IP When operating over IP the SCPS SP uses the Internet protocol number reserved for private encryption protocols Refer to section 2 5 Customizing the SCPS Environment for information on how to incorporate specific protocols into the C library Within the SCPS TP users may customize the specific protocol capabilities that are included in the build The flags to control this customization are also described in section 2 5 1 3 5 Lower Layer Services The SCPS Reference Implementation operates outside the Unix kernel as an application process It uses the kernel s socket interface as a substitute for direct access to lower layer devices The SCPS Reference Implementation may operate over many different types of lower layer services to allow flexibility in the development and execution of SCPS based applications Users may configure the SCPS protocol suite to operate directly over a Raw IP interface or over a UDP
11. Unix based environments to which the Reference Implementation has not already been ported some effort may be required However the Reference Implementation has been developed in a portable manner without depending on capabilities that are not typically found on Unix based platforms 1 3 Philosophy of the SCPS Reference Implementation The following section describes the philosophy behind the development of the SCPS Reference Implementation 1 3 1 Portability The SCPS Reference Implementation was developed in the C programming language and executes in application space on UNIX based machines It uses system calls common to most UNIX based machines and is therefore portable to many types of execution environments The transport layer and below of the SCPS Reference Implementation has been ported to the following environments e Sun Microsystems Sun 3 60 hardware platform running the Sun OS 4 1 1 operating system e Sun Microsystems SPARCstations hardware platform running either the SunOS 4 1 3 or SunOS 4 1 4 or Solaris 2 5 or Solaris 2 6 operating system e Intel 80x86 hardware platform running the FreeBSD operating system e Intel 80x86 hardware platform running the NetBSD operating system e Intel 80x86 hardware platform running the Linux operating system e Silicon Graphics Indigo hardware platform running the IRIX operating system The SCPS File Protocol SCPS FP has been ported to all of the above environments except Solaris Net
12. WN 97W0000095 WORKING NOTE User s Manual for the SCPS Reference Implementation Software September 1997 Robert C Durst Patrick D Feighery Mary Jo Zukoski Sponsor NASA Contract No F 19628 94 C 0001 Dept No W15F Project No 03970639 O 1997 The MITRE Corporation Washington C Center McLean Virginia Abstract This document provides the information necessary for individuals receiving the Space Communications Protocol Standards SCPS Reference Implementation Software Release Distribution version 1 0 to install and use the software KEYWORDS SCPS SCPS FP SCPS TP SCPS SP SCPS NP Reference Implementation Supporting Documentation Table of Contents Section Page Introduction 1 1 1 What is SCPS 1 1 2 The SCPS Reference Implementation 2 1 3 Philosophy of the SCPS Reference Implementation 3 1 3 1 Portability 3 1 3 2 User Interface 4 1 3 3 Implementation Organization 4 1 3 4 Implementation of Protocol Features 5 1 3 5 Lower Layer Services 6 1 3 6 Execution Speed 7 1 4 Software Included in the SCPS Reference Implementation Software Distribution Release 7 1 5 Supporting Documentation 8 Building SCPS 9 2 1 Environment 9 2 2 Extracting the SCPS Reference Implementation Software Distribution 10 2 3 Pre build Configuration Actions 10 2 3 1 Configuring the SCPS Lower Layers 10 2 3 2 Configuring the SCPS demonstration applications 13 2 3 3 Configuring the SCPS File Protocol 13 2 3 4 Configuring SCPS TP Compile time Options
13. aluation and experimentation with the protocols by potential users of the SCPS capabilities The SCPS Reference Implementation software also contains SCPS utilities sample client server applications and a benchmarking tool The protocols implemented in this distribution of the SCPS Reference Implementation are based on the versions of the standards released for review within the international space community under the auspices of the Consultative Committee for Space Data Systems and within the United States Department of Defense space community under the auspices of the Space and Missile Systems Command SMC and the Defense Information Services Agency DISA The specific versions of the standards are listed in the reference s section of this document It is anticipated that subsequent releases of this Reference Implementation will track changes to the protocols resulting from national and international review SAIC Inc in McLean VA developed the SCPS File Protocol SPARTA Inc in Columbia MD developed the SCPS Security Protocol The MITRE Corporation in Reston VA developed the SCPS Transport and Network Protocols The MITRE Corporation also integrated the four SCPS protocols with the assistance of the other developers The SCPS Reference Implementation has been mainly developed on a Sun SPARCstation running the Sun OS 4 1 3 operating system However it has been ported to many other environments as described later in this section For
14. authors The SCPS Reference Implementation has been developed to be portable across most Unix type operating systems There are some operating system specific portions of the software and users porting to other operating system platforms than those mentioned above may need to make modifications to the code Users should also note that the Reference Implementation has not been ported to the Microsoft Disk Operating System DOS or Windows environments Users wishing to undertake such a portation task are encouraged to contact the developers via the feedback mechanisms listed later in this document 1 3 2 User Interface The SCPS Reference Implementation has adopted a policy to capitalize on established interfaces for network applications to minimize SCPS software development efforts The Berkeley socket interface 1s the most popular network interface to the Internet protocols for network applications development The SCPS lower layer application interface mirrors the Berkeley socket paradigm This approach also mitigates technical risks by exploiting Operational experience that the Internet protocols have accrued The SCPS File Protocol presents the same user interface at the client as the Internet File Transfer Protocol Again the purpose of this decision was to maximize user familiarity with the interface and to minimize development costs 1 3 3 Implementation Organization The SCPS Reference Implementation is distributed in a compressed tar
15. delayed ACKs 1 ACK every segment 2 ACK every other segment Disable SCPS Selective Negative Acknowledgment SNACK Disable RFC 1323 TimeStamp operation if supported by peer Sets the Maximum Transmission Unit MTU in bytes for this connection Sets the SCPS rate control value in bps Sets the SCPS precedence level Perform a ping pong command response test Enable Record Boundaries on SOCK_SEQPACKET sockets 35 Appendix D List of Files in Reference Implementation Distribution SCPS directory Top level directory ib b Directory containing SCPS documentation in abobe pdf format F include Directory containing SCPS include files required by SCPS applications li Directory containing SCPS library required to be linked by SCPS applications source Directory containing SCPS source code for SCPS TP SCPS SP SCSP NP and IP tcpdump Directory containing patch file for tcpdump version 3 4a5 allowing it to understand SCPS lower layer protocols SCPS source directory SCPS TP SCPS SP SCPS NP IP and support files Error reporting routines EITOTS C Error reporting routines get_local_internet_addr c Routines for acquiring IP addresses remote and local Header files to support building and parsing IP headers Header files to support lower layer interfaces Routines for interfacing with lower layers 37 SCPS NP management information base header file Routines defining lower layer interface out of SCPS TP
16. diffs to tcpdump that allow it to understand the SCPS lower layer protocols In addition to the source and header files there are some configuration files that are used at run time to support the SCPS Security Protocol and the SCPS Network Protocol These files must be adapted to your particular network environment and are discussed in section Sal 1 5 Supporting Documentation The MITRE Working Note WN 97W0000018 discusses the SCPS Transport Protocol providing background material and manual pages describing the options that may be invoked by applications The MITRE Working Note WN 97W0000026 provides similar information for the SCPS Network Layer protocol Pdf versions of these documents and of this document are located in the docs directory of the SCPS distribution Section 2 Building SCPS This section provides information necessary to build a distribution of the SCPS protocol suite We first discuss the operating environment noting those to which the SCPS Reference Implementation has been ported and tested Next we describe how to extract the SCPS Reference Implementation from its distribution file Third we discuss the steps that each user must perform before building the SCPS Reference Implementation for the first time Finally we discuss the make procedure and the results from that procedure that the user should expect 2 1 Environment The SCPS Reference Implementation has been developed to execute on various hardware p
17. e command line encap udp To configure the encapsulation protocol to be UDP IP in loopback mode the following option must be included on the configure command line encap loop For example if the SCPS Lower layer were configured to include the SCPS Network Protocol the SCPS File Protocol and run over UDP IP i e TP SP NP UDP IP the following is how it would be configured configure scpssp yes scpsnp yes encap udp The configuration command script uses the information supplied by the user and the information that it determines about the host machine to create a Makefile that controls the software build operation Upon execution the configuration command script will echo the configuration decisions supplied by the user or default values and information regarding the host configuration The following results from executing the above example on a Sun Sparc workstation using the SunOS 4 1 3 operating system configure scpssp yes Scpsnp yes encap udp SCPS SP set to yes SCPS NP set to yes Encapsulation set to udp Configuring make file for sparc sun sunos4 1 3_Ul This completes the pre build configuration of the SCPS Lower Layers with the possible exception of user modifications to the default SCPS TP configuration These possible modifications are described in section 2 3 4 12 2 3 2 Configuring the SCPS demonstration applications There are no user configurable options for the SCPS demonstration applica
18. encapsulation IP Loopback to same machine via UDP IP SCPS NP NP in IP encapsulation NP in UDP IP encapsulation NP Loopback to same machine via UDP IP 1 3 6 Execution Speed The SCPS Reference Implementation was developed to be portable to many environments To make the SCPS protocols sufficiently generic to run under many different environments execution speed has been sacrificed We have attempted to minimize the performance impacts but some are unavoidable Of particular note is the fact that the protocols execute outside the operating system kernel and will be adversely affected by writes across the kernel to application interface This effect will become more significant as packet sizes decrease because the per packet overhead increases in relation to the amount of user data being transmitted However under certain circumstances the SCPS Reference Implementation has been able to operate at a sustained rate of over 27 million bits per second on a SPARCstation 20 using an ATM interface to a DS3 link 1 4 Software Included in the SCPS Reference Implementation Software Distribution Release The SCPS Reference Implementation software distribution release contains C language source files to create the SCPS library and the SCPS file protocol both client and server Also provided with the software distribution is an example of a client server application using the services of the SCPS lower layer protocols aSCPS benchmarking tool and
19. entation in abobe pdf format this document SCPS include directory Include Files SCPS header file to be included by all applications SCPS header file to be included by all applications SCPS lib directory Application Files Makefile Makefile supporting the make clean operation SCPS tcpdump directory Tcpdump patches README README describing how to apply the patch to tcpdump apply_scps_tcpdump_patch Bourne shell script to patch tcpdump tcpdump 3 4a5 scps diff Patch file containing diffs for tcpdump allowing it to understand the SCPS lower layer protocols 41 Appendix E Problem Report Form Name of Organization Address of Organization E mail Address Classification of Problem Found Summary of Problem Found Version of SCPS Code Configuration Environment Scenarios Detailed Description of Problem include copy of Makefile and packet traces if applicable 43 Glossary BETS DISA DOD GCC GNU IP NASA NP SCMP SCPS SCPS FP SCPS NP SCPS SP SCPS TP SMC SNACK TCP TP UDP Best Effort Transport Protocol Defense Information Services Agency Department of Defense GNU C Compiler GNU Not Unix Internet Protocol National Aeronautics and Space Administration Network Protocol SCPS Control Message Protocol Space Communication Protocol Standards SCPS File Protocol SCPS Network Protocol SCPS Security Protocol SCPS File Protocol Space and Missile Systems Co
20. er 1997 Space Communications Protocol Specification SCPS Transport Protocol SCPS TP Draft Recommendation for Space Data System Standards CCSDS 714 0 R 3 Washington D C CCSDS September 1997 Space Communications Protocol Specification SCPS File Protocol SCPS FP Draft Recommendation for Space Data System Standards CCSDS 717 0 R 3 Washington D C CCSDS September 1997 MIL STD 2045 43000 Network Protocol for High stress Resource constrained Environments Draft 30 September 1997 Standardization Document Order Desk 700 Robbins Avenue Building 4D Philadelphia PA 19111 5094 MIL STD 2045 43001 Security Protocol for High stress Resource constrained Environments Draft 30 September 1997 Standardization Document Order Desk 700 Robbins Avenue Building 4D Philadelphia PA 19111 5094 MIL STD 2045 44000 Transport Protocol for High stress Resource constrained Environments Draft 30 September 1997 Standardization Document Order Desk 700 Robbins Avenue Building 4D Philadelphia PA 19111 5094 MIL STD 2045 47000 File Protocol for High stress Resource constrained Environments Draft 30 September 1997 Standardization Document Order Desk 700 Robbins Avenue Building 4D Philadelphia PA 19111 5094 Durst R C et al User s Manual for the SCPS Transport Protocol MITRE Working Note WN 97 W0000018 March 1997 10 Durst R C and M J Zukoski User s Manual for the SCPS Network Protocol MITRE
21. er application is must be executed before the client application The following is an example of using scps_resp To receive a stream of data from remote hosts at a rate of 1 000 000 bps using SCPS compression type the following command on the host scps_resp R 1000000 C This will initialize the server and wait for clients to connect Developers of application servers using the services of the SCPS protocol suite are encouraged to examine the source code as a possible method of implementing SCPS based servers Appendix A provides a UNIX manual page description of the scps_resp application 21 3 4 2 SCPS Client The program scps_init is an example of implementing a network client application using the services of the SCPS protocols This program along with its peer program scps_resp show the interaction of application using the services of the SCPS protocol suite This program allows users to set various SCPS TP options Since scps_init is the client application is must be executed after the server application The following is an example of using scps_init To send a stream of data from to a remove server hostb at a rate of 1 000 000 bps using SCPS compression type the following command on the local host scps_init R 1000000 C hostb This will initialize the client connect to the waiting server send a stream of data and close the connection Developers of application clients using the services of the SCPS protocol s
22. lable via anonymous ftp from ftp ee lbl gov must be obtained To successfully build tcpdump 3 4a5 the library libpcap 0 4a5 must be acquired and is also available from the above ftp size To extend tcpdump to understand the SCPS lower layer protocols copy these two files from the SCPS tcpdump directory into the tcepdump 3 4a5 directory and execute the apply_scps_tcpdump_patch script After the patch has been applied reexecute the tcpdump configure utility and make tcpdump according to its directions 17 Section 3 Using SCPS This section provides information necessary to configure the SCPS protocol suite and develop network application programs using SCPS protocol services This section also provides information on the sample SCPS application examples tools and utilities distributed with the SCPS Reference Implementation software 3 1 Configuring SCPS After the SCPS Reference Implementation Software Release Distribution has been build for the particular environment certain tables must be configured before SCPS application may be executed These tables are the SCPS routing table the SCPS address mapping table and the SCPS security requirements 3 1 1 Configuring the SCPS Routing Table When using the SCPS Network Protocol the SCPS routing table must be configured to create routes between the SCPS entities The SCPS routing table is staticly configured by reading in the file npNextHopFile Routing entries within SCPS are interpre
23. latforms and operating system environments The lower layers transport and below of the current SCPS Reference Implementation supports the following environments e Sun Microsystems Sun 3 60 hardware platform running the Sun OS 4 1 1 operating system e Sun Microsystems SPARCstations hardware platform running either the SunOS 4 1 3 or SunOS 4 1 4 or Solaris 2 5 operating system Intel 80x86 hardware platform running the FreeBSD operating system Intel 80x86 hardware platform running the NetBSD operating system Intel 80x86 hardware platform running the Linux operating system Silicon Graphics hardware platform running the IRIX operating system It should be noted that the SCPS File Protocol has been developed for the SunOS FreeBSD and Linux operating system It has not been ported to the Solaris NetBSD or IRIX operating systems The SCPS Reference Implementation must be built using the GNU gcc compiler This is a freely available C compiler that has been ported to many environments The SCPS Reference Implementation software has been developed using GNU gcc versions 2 5 8 2 6 3 and 2 7 2 GNU gcc versions 2 6 1 2 6 2 2 7 0 and 2 7 1 have known problems and should not be used when building the SCPS Reference Implementation 2 2 Extracting the SCPS Reference Implementation Software Distribution The SCPS Reference Implementation has been distributed in a compressed tar format Before the software can be built for a particular environme
24. le of the configure command with non default values for all parameters configure size medium tp no debug yes Configuring make file for sparc sun sunos4 1 3_Ul Created Makefile system sunos size medium debug on Using Operating System sockets Successful execution of the configure utility completes the configuration of the SCPS FP software 2 3 4 Configuring SCPS TP Compile time Options The SCPS TP is typically configured to allow using applications to request optional capabilities at run time By default these optional capabilities are included in the software so that they may be invoked as necessary Some users may wish to remove capabilities that are not currently required In the Makefile and the template for the Makefile Makefile in there is a variable called SCPS_TP which is specified as a sequence of define constants Each of these define constants causes certain SCPS TP capabilities to be included in the compilation These constants are defined by being preceded by D The possible define constants with their D directives are described below 14 DCONGEST Include congestion control software TCP Vegas style DVJ_CONGEST Note DCONGEST MUST be specified also Enable standard TCP congestion control in addition to TCP Vegas style congestion control DOPT_SCALE Enable the window scaling capabilities defined in RFC 1323 DOPT_TSTMP Enable the TCP timestamps option defined in RFC 132
25. mmand Defense Information Services Agency Selective Negative Acknowledgment Transmission Control Protocol Transport Protocol User Datagram Protocol 45
26. ne SCPSSp yes The default is to not include the SCPS Security protocol i e scpssp no To configure the SCPS lower layers to include the SCPS Network Protocol the following option must be included on the configure command line SCPSNP y S The default is to not include the SCPS Network protocol i e scpsnp no but rather use IP The following option is used to configure the encapsulation protocol for the SCPS lower layer protocols which are not using the SCPS Network Protocol To configure the encapsulation protocol to be IP the following option must be included on the configure command line encap raw To configure the encapsulation protocol to be IP in IP the following option must be included on the configure command line encap raw_encap To configure the encapsulation protocol to be UDP IP the following option must be included on the configure command line encap udp To configure the encapsulation protocol to be UDP IP in loopback mode the following option must be included on the configure command line encap loop 11 The following option is used to configure the encapsulation protocol for the SCPS lower layer protocols using the SCPS Network Protocol To configure the encapsulation protocol to be NP in IP the following option must be included on the configure command line encap raw To configure the encapsulation protocol to be UDP IP the following option must be included on the configur
27. nt it must be uncompressed and unarchived To uncompress the software distribution enter the following command uncompress SCPS_RI_1 1 1 tar Z This will result in the file SCPS_RI 1 1 1 tar archive file to be created To unarchive this file enter the following command tar xf SCPS_RI_1 1 1 tar The result of this command will be the creation of a directory named SCPS that contains the files and directories described in Appendix D The SCPS directory will be created as a subdirectory of the current working directory from which the tar command was executed and will be referred to as the top level directory in subsequent sections 2 3 Pre build Configuration Actions Before one builds the SCPS Reference Implementation for the first time the user must perform some configuration actions These actions involve executing configuration scripts and providing parameters to those scripts to convey the user s wishes Three separate configuration actions must be taken The following paragraphs describe these configuration steps In addition to these mandatory actions the user may wish to reconfigure some of the internal options within the SCPS TP This activity will be discussed after the discussion of the configuration steps 2 3 1 Configuring the SCPS Lower Layers The configuration process for the SCPS lower layer protocol software involves two actions that are combined into a single configuration command The first of the two acti
28. ons is to determine the specifics about the host computer in terms of CPU type and operating system This is performed in an automated manner with no user input required beyond starting the configuration command script The second of the two actions is for the user to inform the command script about how to configure the SCPS lower layer protocol software There are three issues to be addressed 1 Should the SCPS stack include the SCPS Security Protocol 2 Should the network layer protocol be IP or the SCPS Network Protocol 3 What form of lower layer encapsulation should be used Refer to section 1 3 5 for a discussion of the alternatives available 10 The result of each of these decisions is passed to the configuration command script as parameters The configuration command script will use a default value for any parameter that is not supplied The name of the configuration command script is configure To invoke the configuration command script and accept all of the default values for parameters one would change directory to the source subdirectory under the SCPS directory and execute the command configure The preceding the command name is to ensure that the configure command in the source directory is executed rather than any others that may be resident on the system To configure the SCPS lower layers to include the SCPS Security Protocol the following option must be included on the configure command li
29. portunities for future standardization and interoperability both within and between these communities may rapidly emerge Reduced life cycle costs as well as increased reliability maintainability portability supportability and securability are expected to result from these common standards The primary scope of the SCPS project is to recommend and develop data communications protocol standards for the transfer of information between space mission end systems The ends of a data flow may be a computer located on the ground which is communicating with a remote computer located in space or two communicating computers that are located in space and separated by one or more in space communications links or combinations of both The primary focus of the SCPS is therefore on the transfer of data through space to ground ground to space and space to space communications subnetworks While satisfying space mission requirements constitutes the primary focus the project has kept in mind the needs of similar communication environments Stressed communications environments such as in battlefield situations characterized by long propagation delays noisy and bandwidth constrained communications links intermittent connectivity and resource constrained end systems Commercial wireless environments such those provided by satellite or radio systems supporting Internet or Intranet traffic The SCPS project is a joint activity between the National Aeronautics
30. program Scps_ttcp allows the user to set various SCPS options via the command line OPTIONS A ackdelay Set the value of the maximum time in milliseconds a SCPS TP entity must send a TP acknowledgment b size Set size of socket buffer in bytes B Enable SCPS Best Effort Transport Service BETS operation if supported by the peer C Enable SCPS compression operation is supported by the peer D Don t buffer SCPS TP writes sets SCPS NODELAY option G Enable TCP Vegas Congestion control algorithm L Set SCPS socket to non blocking mode M mtu Sets the Maximum Transmission Unit MTU in bytes for this connection R rate Sets the SCPS rate control value in bps S Disables SCPS Selective Negative Acknowledgment SNACK 31 T Disables SCPS TimeStamp operation Enable SCPS BETS SCPS compression SCPS SNACK and SCPS TimeStamp options 32 Appendix C Manual Page for scps_ttcp Application SCPS_TTCP 1 NAME scps_ttcp test SCPS TP performance SYNOPSIS scps_ttcp t u s p port 1 buflen b size n num bufs A align O offset f format a D v E C G D M m mtu R rate L priority e host lt in scps_ttcp r u s p port 1 buflen b size A align O offset f format B T v E C G a D M m mtu R rate L priority e host lt in host gt out DESCRIPTION Scps_ttcp times the transmission and recep
31. que g h SCPS Control Message Protocol routines scmp c gc Precedence queuing routines qh Header file for precedence queuing routines Various constant definitions 38 SCPS FP directory SCPS FP files Header file for record update Header file for ftp libe c Library routines for client Header file for client library routines libs c Library routines for server Routine to write client logfile logs c Routine to write server logfile 39 1x_avail h server c Header file for transport layer interface SCPS apps directory Application Files SCPS bin directory Executable Files Makefile Makefile supporting the make clean operation Sample initialization file for Security Association database must be modified to suit your network Sample address translation specifications for SCPS NP must be modified to suit your network npNextHopFile Sample static routing table for SCPS NP must be modified to suit your network SAMPLE SA table Write protected versions of the above for reference SAMPLE npIP_NP_File SAMPLE npNextHopFile 40 SCPS docs directory Documentation about SCPS NP_Users_Manual pdf User s manual of the SCPS Network Protocol in abobe pdf format TP_Users_Manual pdf User s manual of the SCPS Transport Protocol in abobe pdf format FP_Readme pdf Readme file for the SCPS File Protocol in adobe pdf format RL pdf User s manual of the SCPS Reference Implem
32. tape archive file that when uncompressed and extracted from the archive creates a SCPS directory and several subdirectories The subdirectories are as follows SCPS File Protocol source code apps Example applications that operate directly over SCPS TP via the scps socket interface bin Directory into which the executable code will be placed after compilation Also the initial location for storage of various initialization files for the SCPS Security Protocol and the SCPS Network Protocol include The directory that contains header files that are included directly or indirectly by application programs using the SCPS protocols Refer to the manual pages of the SCPS socket interface calls for specifics lib The directory that contains the SCPS library file which is comprised of the object files that support the configuration built by the user source The directory that contains source code for the SCPS TP SCPS SP and SCPS NP plus supporting software The supporting software includes the interface code to the lower layers code to perform buffer management and a simple thread scheduler for multitasking external to the operating system kernel docs The directory that contains adobe pdf versions of this file and the SCPS TP and SCPS NP user s guide tcpdump The directory that contains files to patch tepdump 3 4a5 allowing it to understand the SCPS lower layer protocols 1 3 4 Implementation of Protocol Features The SC
33. ted in the following manner To reach a End System whose IP address is X forward the packet to the next hop system whose IP address is Y The format of the file is the following The first line contains the IP address of the machine The following lines contain a pair of IP addresses where the first address is the destination IP address and the second address is the next hop IP address It should be noted that all addresses in this file must be in their hexadecimal form 3 1 2 Configuring the SCPS Address Mapping Table When using the SCPS Network Protocol the SCPS address mapping table must be configured to map IP address to a corresponding SCPS NP address This is required in the application are using any SCPS NP address families Reading in the file npIP_NP_File staticly configures the SCPS routing table The format of the file is the following A pair of addresses separated by a space where the first address is the Extended form of the address and the second address is its corresponding basic form It should be noted that all addresses in this file must be in their hexadecimal form 3 1 3 Configuring the SCPS Security Requirements When using the SCPS Security Protocol the protocol must be configured before any of the security services may be used Reading in the file SA_table statically configures the SCPS 19 security protocol The format of the file is the following Each line contains 10 fields separated by a space Figure 1 is an e
34. this version of the Reference Implementation users must incorporate the thread scheduler into their applications and explicitly pass control to the scheduler and on to the SCPS stack to watch for incoming packets on a frequent basis during execution The exact frequency depends upon packet arrival rates Users explicitly pass control by inserting calls to the function sched in their code The flow of control in the user s application is unaffected by the presence of these calls In addition to placing calls to sched in the body of the user s application the user must perform the start up actions of initializing the thread scheduler and the SCPS stack in the main routine and then pass control to the scheduler An example of this appears in the scps_initiator c file in the apps directory Examine the main function from the comment Boilerplate code to the call to exit 0 3 4 SCPS Application Examples The SCPS Reference Implementation software distribution release provides two examples to aid users in understanding how to develop application using the SCSP protocol suite 3 4 1 SCPS Server The program scps_resp is an example of implementing a network server application using the services of the SCPS protocols This program along with its peer program scps_init show the interaction of application using the services of the SCPS protocol suite This program allows users to set various SCPS TP options Since scps_resp is the serv
35. tificially low measure of connection delay However the performance numbers reported by the receiving side will not display this bias 23 Section 4 Feedback The SCPS team encourages feedback from users concerning their experiences using the SCPS Reference Implementation software distribution release This allows the SCPS project to develop a greater insight into the types of applications and programs considering the SCPS protocols and to identify those modifications to the Reference Implementation that would make it more useful The SCPS team is also working on developing an automated problem reporting system This system will probably be based on GNU gnats software Until this system in completed it is requested that all problems be written and sent to the MITRE Corporation Appendix E provides a sample form for reporting problems concerning the SCPS Reference Implementation Please direct all comments and suggestions to Mr Robert C Durst MS W650 The MITRE Corporation 1820 Dolley Madison Blvd McLean Virginia 22102 25 List of References 1 1 Space Communications Protocol Specification SCPS Network Protocol SCPS NP Draft Recommendation for Space Data System Standards CCSDS 713 0 R 3 Washington D C CCSDS September 1997 Space Communications Protocol Specification SCPS Security Protocol SCPS SP Draft Recommendation for Space Data System Standards CCSDS 713 5 R 3 Washington D C CCSDS Septemb
36. tion of data between two systems using the SCPS TP protocols For testing the transmitter should be started with t and s after the receiver has been started with r and s Scps_ttcp also provides the capability of determining round trip throughput Tests lasting at least tens of seconds should be used to obtain accurate measurements Scps_ttcp allows the user to set various SCPS options via the command line OPTIONS t Transmit mode T Receive mode u Use UDP instead of TCP S If transmitting source a data pattern to network if receiving sink discard the data Without the s option the default is to transmit data from stdin or print the received data to stdout 33 1 length b size Length of buffers in bytes default 8192 For UDP this value is the number of data bytes in each packet The system limits the maximum UDP packet length This limit can be changed with the b option When testing UDP performance it is important to set the packet size to be less than or equal to the maximum transmission unit of the media Otherwise IP fragmentation will distort the test For Ethernet set the length to 1508 bytes Set size of socket buffer The default varies from system to system This parameter affects the maximum UDP packet length It may not be possible to set this parameter on some systems n numbufs Number of source buffers transmitted default 2048 p port a ackdelay A align O offset f format
37. tions They need only to determine the type of CPU and operating system From the SCPS directory change directory to the apps subdirectory and execute the configuration command script in the following manner configure If executed on the same system as the example above one should see the following output Configuring make file for sparc sun sunos4 1 3_Ul This completes the configuration of the SCPS demonstration applications 2 3 3 Configuring the SCPS File Protocol The configuration process for the SCPS File Protocol is similar to that for the SCPS Lower Layers in that the software must determine the type of the local CPU and operating system and it must receive information from the user regarding configuration options Three major configuration decisions must be made 1 Should the SCPS FP implementation size be small roughly corresponding to the SCPS FP Conforming Minimum Implementation from the SCPS FP specification or medium roughly corresponding to the SCPS Conforming Full Implementation or large roughly corresponding to the FTP Interoperable Implementation Refer to the SCPS FP specification CCSDS 717 0 MIL STD 2045 47000 for more details on these capabilities 2 Should the SCPS FP operate over SCPS TP or over the system s in kernel TCP implementation 3 Should debug information be printed to the screen during operation As with the SCPS Lower Layer configuration
38. uite are encouraged to examine the source code as a possible method of implementing SCPS based clients Appendix B provides a UNIX manual page description of the scps_init application 3 5 SCPS Utilities The SCPS Reference Implementation software distribution release provides five utilities to aid users in using and configuring SCPS 3 5 1 SCPS ttcp Scps_ttcp is a benchmarking tool for determining SCPS performance between two systems Scps_ttcp is based on the commonly used performance test program ttcp Ttcp was originally developed at the US Army Ballistics Research Lab BRL and has been released into the public domain It was then modified by the MITRE Corporation to execute over a SCPS protocol stack The following are some examples of using scps_ttcp To send a stream of data from one host to another host at a rate of 1 000 000 bps using SCPS compression type the following command on the remote receiving host scps_ttcp r s R 1000000 And type the following command on the local sending host scps_ttcp t s R 1000000 remote_host 22 After executing scps_ttcp will display performance information about the connection upon its completion Note that as with regular ttcp the sending host will display its performance when the last application data is enqueued for transmission rather than when it receives an acknowledgment from the remote host In long delay and or high bit error rate environments this will result in an ar
39. xample for a SA_table file Source IP address In hexadecimal format Destination IP address In hexadecimal format crypt key ASCII key crypt block size Length of the crypt key in octets crypt algorithm O for DES 1 for XOR Integrity Check Value key ASCII key for Integrity check algorithm Integrity Check Value size Length of the Integrity Check Value key in octets Integrity Check Value algorithm 0 for MD5 Security Label Length Length of the security Security Label Security label Security QoS Security capabilities allowed for this connection Simply and the following values together Ox1 for Confidentiality 0x2 for Authentication 0x4 for Security Label and 0x8 for Integrity c0307280 c0307283 KEYKEYE 8 1 MDSPKRY c0307283 c0307280 KEYKEYE 8 1 MDSPKRY c0307280 c0307299 KEYKEYE 8 1 MDSPKRY c0307299 c0307280 KEYKEYE 8 1 MDSPKRY Figure 1 Example of Security Configuration File 3 2 Using SCPS Protocol Services The SCPS Reference Implementation provides a library based method allows a single application to communicate over a SCPS based communication stack The SCPS library must be preconfigured with all necessary information 3 3 Developing Applications using the SCPS Library To develop applications using the SCPS library the SCPS header file scps h must be included in the application and it must be linked in with the SCPS library libscps a created for library based applications 20 In
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