IP over CCSDS resolution

已有 162 次阅读 2011-3-23 05:16 |关键词:Chris%2CBurbu


Hu Xingyi

Space Science and Applied Research,

summary of IP technology is currently widely used on the planet in general and Internet technologies, the use of the network envisaged in the space integration of IP technology will bring enormous benefits world. Is the study of IP over CCSDS space data link layer in the protocol (CCSDS AOS, TC, TM, Proximity-1) to carry IP reported to achieve the transfer. Since 2006, CCSDS were released five versions of the IP over CCSDS Red Book for discussion, revision and practice. This article introduces and discusses the integrated IP over CCSDS related content.

Keywords IP CCSDS earth integrated

I. Introduction

According to reports, January 22, 2010 is the International Space Station (ISS) operations in the U.S. aerospace Timothy Creamer ? Members via the Internet directly from space, with the National Aeronautics and Space Administration (NASA) ground command center in Houston (JSC) conducted a web chat, becoming the first ever Internet space chat heaven and on earth. This shows that ISS and the ground has successfully created a space, the Internet, the ISS Internet access to space.

with the spacecraft internal between the spacecraft and the space between the increasingly complex interactions between, forcing designers to consider the use of network technology to support these interactions, generally considered: the network to carry IP datagram delivery will become increasingly popular. In order to coordinate the spatial organization of the space activities of States, as early as 1982, the Advisory Committee on the International Space Data Systems (CCSDS) to release a set of conventional spatial data system of technical proposal (COS), in 1989 and formally adopted by the Advanced Space Data Systems Recommendations in the rail system (AOS), and since the 90 years since the development of a series of spatial data system protocol specifications and standards. To meet the rapid development of the Internet ground, CCSDS space have targeted a number of communication protocols have been modified and upgraded to form a space network support IP report (PDUs) to pass the CCSDS-SCPS series of space communication protocol specification to meet the requirements of world integration. However,Christian Louboutin Super Woman 120 python boots, the 4 CCSDS space data link protocol (AOS, TC,Christian Louboutin Slingbacks-Christian Louboutin, TM, Proximity-1) is tailored for the space environment are the lack of how to define the link to carry IP information and report any content that perform specific and clear Implementation of operational specification. Then set up a space in the internal CCSDS Internet service (SIS) films, specializing in various forms of network links and protocol of interactive services, basically through the OSI reference model covers the application layer of the network. January 2006 by the SIS chip under the IP over CCSDS Space Link Working Group (SIS_IPO) first published CCSDS 702.1-W-1 White Paper, IP over CCSDS concept came into being 8-October and have issued CCSDS 702.1 -R-0, CCSDS 702.1-R-1 Red Book, published in January 2007 after a CCSDS 702.1-R-2, 2008 年 9 month issued CCSDS 702.1-R-3, until April 2010 issued a CCSDS702.1-R -4 and related text. The intention is to the spacecraft and ground system to achieve through the CCSDS space data link layer protocol to carry the IP datagrams and to establish the recommended CCSDS CCSDS space link in the practice of passing IP_PDUs specification. In addition, ready for commercial (COTS) technology and the introduction of a wide range of interface software to do the groundwork space systems. This approach effectively guide the IP communication layer in the CCSDS specification development and seamless integration.

present, the satellite network technology and Internet technology have been the foundation is a very mature technology,Christain Louboutin Big Lips bootie 120, but in the world in their respective integrated development are exposed to a number of shortcomings. Emerged in recent years, satellite networks and Internet networks in the synthesis and integration, transformation, and amend the shortcomings of their own, combining their respective advantages in the world has made great progress in the integration, the implementation technology is mainly used in satellite ground segment up / down conversion of the Gateway protocol.

CCSDS Space Link Protocol IETF Internet link protocol with the basic difference is that the IETF link protocol is symmetrical in design, that both in the data stream to provide consistent service,Christian Louboutin Open Lips 120 suede pumps, and CCSDS link layer protocol the design is asymmetric, which provides for two different data flow procedures. This is because one side is the CCSDS space link protocol vector (SV), and the other is the ground station (GS). They have different procedures. In addition there are also forward (from the GS to the SV) and return (from SV to GS) data flow procedures and different link layer frame format, the first data stream carrying the remote control commands, the return data stream carrying telemetry information.

IP over CCSDS concept of space in the CCSDS link layer protocol (AOS,Christian Louboutin Evening shoes, TC, TM, Proximity-1) on the realization of IP datagrams (PDUs) for transmission, that is how the link in the CCSDS carry IP datagram to achieve (including the IP datagram header compression), the establishment of routing, switching aspects of the configuration, space management and elements of IP end to end Internet security protocols and technologies, and engineering operation, management practices and operational characteristics, etc. research. Of course, the format and delivery business PDU primitives. IP over CCSDS space and ground will enable a consistent network protocol, can achieve space-based network and the foundation of the network seamlessly.

This article describes the world in recent years, is committed to the integration of CCSDS interconnection, interoperability and seamless connectivity and interoperability to achieve a transparent way, CCSDS IP data reported by the recommended CCSDS link layer transfer approach . CCSDS also reflects the business as much as possible the use of ground and COTS products to Internet Protocol IP-based network communication idea of ??space.

Second, IP over CCSDS implementation method

as aforesaid, to integrate satellite communication network and ground network, CCSDS has released so far to support the delivery of IP reported SCPS series, Proximity- 1 space link protocol, SLE and other standards. But still lack the spacecraft and the spacecraft can achieve outside the IP space by CCSDS link layer protocol data transfer applications, the practice of clear and detailed specifications in order to truly integrated earth transparently interconnect, interoperability and mutual operation.

Usually, IP data reported through the CCSDS Space Link (air - air-way, air - two-way) transmission protocol method can have several options:

1, directly IPv4, IPv6 datagrams into one or more frames within a CCSDS data link or other of the CCSDS packet to re-confirm with them. This option uses CCSDS AOS Virtual Channel Packet (VCP), remote control VCP, remote multiplexer access point (MAP) package (MAPP) transmission business;

2, the series provided by the user data flow packages IPv4, IPv6 datagrams. Will have to pass IPv4, IPv6 packet as a serial data stream into 8-bit bytes of CCSDS Space Link frame. This option uses CCSDS AOS Virtual Channel Access (VCA) or remote MAP Access (MAPA) to pass the business;

3, using CCSDS packaging operations to deliver IPv4, IPv6 datagrams. Will have to pass IPv4, IPv6 datagram encapsulated in CCSDS package eleven package, in one or more of CCSDS Space Data Link frames are passed directly encapsulated package. This option uses CCSDS encapsulation (ENCAP) business;

2,3 are the package, which can be combined into two kinds of selection (Figure 1a, Figure 1b):

1 ), CCSDS space link-layer protocol data can directly support all versions of CCSDS IPv4 packet convergence layer without any intermediary. CCSDS has defined a support IPv4 reported in the CCSDS space link listed on the transfer of the business. CCSDS data link protocol supports the transmission of two types of IPv4 reported, that is the main channel and virtual channels. Because users can only use CCSDS virtual channel multiplexing different data packet types, so the Red Book is concerned only with the transmission of virtual channel. Redbook's main purpose is to recommend the most appropriate link on the IP over CCSDS transfer business. This method is non-compressed IPv4 packets directly into CCSDS transfer frame, CCSDS space data through the chain of transmission. At this point, only IPv4 packet header the IPv4 datagram is not compressed. IPv4 datagram header length field is being used to support the transfer frame to define the IPv4 datagram. That is, in one or more of CCSDS Space Data Link frames within the independent transmission of uncompressed IPv4 datagram or recognized in other CCSDS packet multiplexed uncompressed IPv4 datagrams. This option uses CCSDS AOS, TM, TC or Proximity-1 Virtual Channel Packet (VCP) business or TC Multiplexer Access Point Package (MAPP) transmission business;

Figure 1a. IP over CCSDS data link choice

2), will be compressed or uncompressed IPv4 header or IPv6 datagram encapsulated datagram service eleven using CCSDS CCSDS package package insert. And then pass directly into the package bag CCSDS space data of one or more frames within the transmission chain. The method by CCSDS AOS, TM, TC or Proximity-1 Virtual Channel Packet (VCP) business use of the CCSDS package (ENCAP) business. For the IPv4 packet header compression due to its length field can no longer be used to define the data reported, so only use this method. Thus, this method provided by the Department in encapsulation of the encapsulated packet header length. For IPv6, regardless of whether compression can always use this method. This is because the IPv6 packet is not recognized as a CCSDS packet version number (PVN). However, when the project in order to simplify the compressed and uncompressed all RF link choose to use a protocol stack, this method can not avoid the simultaneous users of compressed and uncompressed IPv4 datagrams.

Figure 1b. IP over CCSDS data link selection

further research shows that the latest IP over CCSDS Space Link Red Book (CCSDS702.1-R-4) is a recommended option (Figure 2)

Figure 2. CCSDS data link in the recommended way to transfer IP

that is,Christian Louboutin JS 100 paneled leather pumps, to achieve IP over CCSDS approach is anticipated in all IP_PDU CCSDS IP extension in (IPE) bytes (see the chain Road identifier CCSDS135.0-B-4), then one by one to the CCSDS package package package (see packaging operations CCSDS133.1-B-2), and in one or more of CCSDS Space Data Link transmission within the direct transmission of the frame These packages package, this approach identifies and defines recommended as CCSDS_IPE all IP_PDUs in AOS, TC, TM, or Proximity-1_VCP business use. For example: CCSDS packaging business is reported in advance of delivery to the IP service data unit payload (SDU) with a head,Christian Louboutin Attention 100 cutout mesh and leather boots, of course, can change the length of SDU can be the same length. Head length can be 1,2,4 or 3,4,6 or 7 by 8 bytes consisting of the domain. (Table 1)

Table 1: CCSDS header

table package, the agreement ID'000 'that is the total length of 1 byte of null encapsulation packet, protocol ID'010' that is IPv4 or IPv6 encapsulation the IP packet,Christian Louboutin New Declic python, and protocol ID'100 'is shown to be restored before CCSDS and IPv6 packets is reservations.

using IP over CCSDS also depends on the habits of the data link protocol, for instance, multi-protocol Frame Relay (MPoFR) allows signal information in the vicinity of the COTS transparent channel between the router to complete the router by-hop (hop-by-hop) in the IP header compression (IPHC) (Figure 3). IP header compression to packet brings performance improvements, the Constellation program's VoIP study confirmed this. In this regard, as noted above, CCSDS CCSDS IP extension to take the call (IPE) of new standards (Space link identifiers CCSDS 135.0-B-4 of Appendix A), from the IP network layer data link layer through space to be compatible with such a low-level signal information channel. IPE use one or more than one optional 'fill byte' to extend the CCSDS header package to allow for the IP protocol can branch demultiplexing. PPP link in the series analog domain or the Ethernet protocol type field in Ethernet. There used to identify the IPE in the number of possible supplementary agreement, the Blue Book recently modified to limit the list of bytes unique to IPE filling IPv4 or IPv6, as well as different IP header compression format. Before the IP packet header in the package be placed immediately after the IPE filling bytes. Not to consider the filling bytes into header part of the package. IP packet processing applications IPE first byte in the pre-filling packaging business together, but only after part of the entire package package.

Figure 3. IPE head

three service interface

business interface is to provide business users and business side of the interface between. Business user side service access point (SAP) access transmission service, service provider to perform in the space link data units passed the business. SAP packets to the access point user input provided by IPE and its subsidiaries as defined IP_PDU link layer routing information (ie spatial data link protocol channel SDLP_Channel) (Figure 4a),Burburry Studded Wellington boots, link layer link-layer address is an identifier level system (ie SDLP_Channel) and Figure 5 shows the channel to explain. CCSDS IP transfer service for each full description can be found in IP over CCSDS space link Redbook Chapter primitive operations. Thus, IP service interface boundary is CCSDS packaging business service access point (SAP).

Figure 4a. CCSDS IP transfer service interface Figure

to IP_PDU CCSDS space link in passing, to provide input to the business side, the services provided by the user through the appropriate unit of data link layer address. For all CCSDS space link layer protocol, the link layer address of the general term known as 'SDLP_Channel', CCSDS data link layer protocol based on the underlying parameters of the business to define SDLP_Channel content:

1) for TM, TC or the AOS of the VCP Service: Global Virtual Channel ID (GVCDID);

2) for the TC packet multiplexing access point (MAPP) Business: GVCID and MAP ID;

< p> 3) for the adjacent spacecraft (Proximity-1): Transfer Frame Version Number (TFVN), spacecraft version identification (SCID), the physical channel identification (PCID), the data field structure identification (DFC_ID) and port identification (Port_ID)

for the VCP data transmission services, users GVCID. GVCID by TFVN, SCID VCID field and CCSDS data link layer protocol in the transmission of frames from the head of the cascade. By specifying GVCID, users on a dedicated special TFVN VCID or frame of a special distribution of the contents of SCID. The MAPP transmission business, provide a global MAP ID or GMAP ID. GMAP ID is GVCID and MAP ID of the cascade. MAP MAP ID support given channel in a complex virtual channel used to provide an additional level of multiplexing. In addition, MAPP business segments and more than able to handle the domain transfer frame data packet maximum transmission unit of the re-assembly. MAP channel only by the TC Space Data Link Protocol support. (Figure 5)

Figure 5. For SDLP_channel parameter identifier and channel

IV,Christian Louboutin Greissimo 85 black pump, the recommended CCSDS IP transfer service

actual delivery method is to use the recommended CCSDS IPE plus package business in the CCSDS space link transmission from the space link identifier in Appendix A (CCSDS135.0-B-4.) listed IP_PDU, to consider in advance IP_PDU CCSDS IPE head, and the result be added to the CCSDS packaging operations ( CCSDS133.1-B-2) defined in the package package. Business users to input IP_PDU IP_PDU_SAP link-layer address of its subsidiaries. IP_PDU depends on the size of the package and the use of CCSDS data link layer protocol, the package can be divided into a number of CCSDS packet transmission frame. CCSDS space link transmission IP_PDU across the CCSDS CCSDS packaging business is the proprietary business (Table 2).

Table 2:. Recommended CCSDS IPv4 packet flow package delivery business

SDLP_channel specified by the CCSDS packet data link layer service access point (SAP). SDLP_channel formation depends on which CCSDS space data link protocol, such as: the AOS, using TFVN (AOS is '01 '), SCID, and VCID phase cascaded GVCID. General, the use of CCSDS Space Data Link 'package business' is because the package provides variable length packets for this reason that the non-synchronized flow. In the fixed-length transmission frame cases, such as: AOS, 'package business' to provide variable-length sub-package and re-assembled into packets of fixed length frames.

provide input to the system, IP packets may have gaps, you can insert empty data to maintain a continuous link spatial data (such as AOS case), but note that this will not bring compliance or poor performance efficiency.

five business data multiplexing unit

how to identify the CCSDS business data unit, which for all CCSDS space data link protocol, the CCSDS Space Packet, SCPS-NP reported that insertion package package and reuse in the transmission side, and at the receiving end shunt, the process of extraction and how to identify the routing. Table 3 provides the data link layer protocol of each CCSDS the main features of the executive summary.

Table 3:. CCSDS link layer protocol of the main features of

to CCSDS AOS Space Data Link example (TC, TM, Proximity-1 like) to discuss business data units (SDUs) What is the input to the AOS frame, is that how the output and how to extract the AOS within the multiplexed frame. AOS without ARQ protocol can be used for relatively high-speed forward / reverse link transmission (Figure 6). When a data source in the CCSDS packet encapsulation (ENCAP) is generated that contains within each of the IPv6

Figure 6. CCSDS AOS frame multiplexing SDU

datagram, the second data source is concurrently CCSDS space packets generated . CCSDS for these SDUs in two different ways of 2 provides the main channel in the same complex with the capacity. Figure 6 shows the Option 1 is to give each SDU type (ie CCSDS space package, package bag) is assigned a unique VCID, in order to separate the ground station and routed directly to these data, you can assign different VCIDs. Another possible is to choose the same 2 (Figure 6 did not), it is also assigned to the two types of single SDU a VCID, and in its use of space on the package and package complex package. As in the header of each SDU has the version number based on its package (PVN) as defined by the length of the field, so the receiving system which can be extracted from the frame SDUs.

six other

on the various AOS, TC, TM, Proximity-1 transfer frame PDU data format, package package structure, Internet protocol extension (IPE) and the primitive operations etc., due to layout constraints,Christian Louboutin Miss Boxe 100 wedge pumps, not repeat them here, those interested can see the IP over CCSDS Space Link Red Book (CCSDS702.1-R-4).

VII Conclusion

both the near-Earth space exploration, or exploration of deep space, the first heaven and earth to address the integration of that interconnection, interoperability and interoperability of communications. According to the Working Group CCSDS_SIS_IPO research on IP over CCSDS space data link concepts, methodology, elements of the business interface,Christian louboutin sales, multiplexing analysis carried out in order to assist in the further understanding and implementation based on IP (IPv4 or IPv6) of the Space Network framework, the development of space exploration in our country there should be a reference. However, for the specific application of IP over CCSDS development and deployment of hardware and software prototypes and the development of CCSDS space data link through the IP packet communications features required, such as: use of COTS routers, but also through case presentations and the Internet operations testing and validation.

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