CN1136706C - Adaption method for integrating Internet with quasi-synchronous digital system - Google Patents

Abstract

The present invention relates to an adaptation method for integrating the internet with a quasi-synchronous digital system. The present invention improves the defects of no standard definition, over-high cost of partial treatment of hardware retransmission, unclear definition of the value of a retransmitting timer, very low efficiency due to a filling function, etc. in the prior art. Moreover, the present invention proposes that one factor of a PDH link access procedure be used for replacing two factors comprising a point-to-point protocol and a high-grade data chain procedure to solve the integration and the adaptation between an internet protocol and the quasi-synchronous digital system. The conception simultaneously supports the fourth version and the sixth version of the internet protocol.

Description

A kind of adaptation method that is used for internet and PDH (Pseudo-synchronous Digital Hierarchy) fusion

Technical field

The data that the present invention relates to internet transmit the field, it is a kind of adaptation method that is used for internet and PDH (Pseudo-synchronous Digital Hierarchy) (english abbreviation PDH) fusion, be mainly used in the core switch router, the edge switch router, based on the high low-end switch of packet switch, user side integrated access equipment and interconnecting and interworking equipment relevant etc. with internet.

Background technology

According to the interrelated data introduction, now be used for the adaptation method that internet and PDH (Pseudo-synchronous Digital Hierarchy) merge, be to adopt " point-to-point protocol " (english abbreviation PPP) to add " high-level data link rules " (english abbreviation HDLC).At internet engineering duty group (english abbreviation IETF), it is defined as (code name) RFC1619 (RFC is the request comment, English Request For Comments).As everyone knows, popularization and application along with computer, the network transmission technology supporting with computer constantly develops, with the internet be the computer network of representative by PDH (Pseudo-synchronous Digital Hierarchy) constantly to extending all over the world, allow electronic information propagate, make electronic information reach each corner in the world by wireless and microwave transmission mode simultaneously with the fastest speed.Along with the day by day increase of electronic information by transmission volume, the quality of electronic information transmission becomes the problem that people pay close attention to day by day.Internet has the unified IP delivery platform in the world, can move countless application and business thereon.PDH (Pseudo-synchronous Digital Hierarchy) (english abbreviation PDH) is that at present best in the world and existing telecommunications transmits one of net resource, and both have extremely strong complementarity, are containing huge market prospects.Internet protocol (english abbreviation IP) is directly at PDH transmission online operation, is countries in the world in recent years, each big telecommunications manufacturer, one of focus of operator and each computation machine company market contention.It also is one of key point of telecommunications network and computer network fusion.Safety, fast, high-quality is by internet and other Network Transmission electronic information, need to adopt corresponding transmission means and adaptation method, not smooth to prevent Network Transmission, information dropout, according to the interrelated data introduction, now be used for the adaptation method that internet and PDH (Pseudo-synchronous Digital Hierarchy) merge, present " point-to-point protocol " (english abbreviation PPP) that adopts, it can encapsulate 30 multiple network agreements, contain and be useful on internet " internet protocol the 4th edition (English IPV4); this protocol fitting method is successful by the MODEM online; also have fire compartment wall, but if be used for PDH (Pseudo-synchronous Digital Hierarchy) (english abbreviation PDH), just comes with some shortcomings and defective.Mainly show:

(1) transmits IP operation for a whole set of PDH, do not have the standard support, cause PPP over PDH can not be used for internet;

(2) for per second 140 megabits and above speed thereof, hardware forwarding part expense is too big during development equipment, when this cover " internet protocol (english abbreviation IP) is directly at wavelength division multiplexing optical cable net (english abbreviation IP over WDM) " is gone up operation, all the more so, because the RFC1619 regulation: recommend to use " LCP (english abbreviation LCP) " and magic number (English is expressed as Magic Number).These two more complicated;

When (3) adopting RFC1619, because PPP need connect, the default value of retransmission timer is decided to be 3 seconds in PPP.For high-speed link, this method is too blunt.Use for concrete engineering, should require to support speed range four corner (differing from 4032 times approximately) from per second 2 megabits to per second 140 megabits.So the value of retransmission timer should be determined according to the time delay that circuit comes and goes.These are not all made stipulations in RFC1619, thereby uncertainty can occur when the apparatus interconnection of different manufacturers;

(4) fill function (English is expressed as Padding Function), the information field of PPP generally will be filled into maximum receive unit (english abbreviation MRU, general provision is 1500 bytes on internet).For general internet packet, as the application of browser (English is expressed as WWW) online (this kind application account for 75% that whole internet uses), the average data packet length is 330 bytes, has average about 350% to be to flog a dead horse like this, and efficient is very low.In addition, it is information field that this filling field also needs a function which is distinguished at receiving terminal, and which is to fill field.This has increased processing expenditure again;

Summary of the invention

The objective of the invention is, improved, and propose and design the adaptation method that is used for internet and PDH (Pseudo-synchronous Digital Hierarchy) fusion that is applicable to various situations at deficiency and defective that prior art exists; Conception of the present invention is only to keep bit-oriented PDH Link Access Procedure (english abbreviation LAPP) between internet protocol (english abbreviation IP) and PDH (Pseudo-synchronous Digital Hierarchy) (english abbreviation PDH), replace address field with many service access points, the encapsulation of realization multi-protocols, can support whole speed ranges of from the Lower Order Virtual Container to the higher order virtual container, (comprising cascade), also be particularly suitable for using the packet switch interface of light, uncertainty without any agreement, this conception can not only solve new equipment development and problems of operation, and has found an extraordinary outlet for China's existing over ten billion Yuan telecommunication transmission resource.

A kind of adaptation method that is used for internet and PDH (Pseudo-synchronous Digital Hierarchy) fusion, comprise the following steps: to receive packet from the network layer device of internet, the type of recognition data bag, type according to identification produces the SAPI identifier, and described packet is converted to the professional code-point of segmentation of first kind frame and reflection transmission priority; Described first kind frame is packaged into the frame format that comprises beginning flag, address field, control field, information field, Frame Check Sequence field and termination flag, to form the second class frame; With the second class frame in bit-oriented mode with to segment on the cascade channel that transmission priority mapping that professional code-point reflected forms to single PDH passage or by a plurality of PDH passages; FCS calculate finish after, transmit leg is checked the entire frame content between two flag of frame, whenever run into five continuous " 1 " will insert automatically following closely during sequence " 0 "; The recipient, before FCS calculates, continuous at five " 1 " afterwards any " 0 ", will be abandoned automatically.

Adaptation method as claimed in claim 1, the SAPI identifier of the described second class frame is corresponding to address field or be inserted on two the information field bytes of the most close control field.

Adaptation method as claimed in claim 1, described cascade channel is by PDH passage (the passage A1 of two or more same rates with the path, A2, An) form, the bit-order of mapping is: the 1st bit of passage A1, the 1st bit of passage A2, the 1st bit of passage A3 ... the 1st bit of passage An, the 2nd bit of passage A1, the 2nd bit of passage A2, the 2nd bit of passage A3 ... the 2nd bit of passage An, the N bit of passage A1, the N bit of passage A2, the N bit of passage A3 ... the N bit of passage An, the maximum number bits of every passage are the basic frame length N0 of the single PDH passage of ITU-TG.704 defined.

Adaptation method as claimed in claim 1, the virtual container of the physical layer of described PDH (Pseudo-synchronous Digital Hierarchy) PDH passage and bandwidth, payload parameter are:

Its speed of E1 is that 2048 kilobits/second are encoded to HDB3

Its speed of E3 is that 34368 kilobits/second are encoded to HDB3

Its speed of E4 is that 139264 kilobits/second are encoded to CMI

Its speed of T1 is that 1544 kilobits/second are encoded to AMI or B8ZS

Its speed of T2 is that 6312 kilobits/second are encoded to AMI or B6ZS or B8ZS

Its speed of T3 is that 44736 kilobits/second are encoded to B3ZS

Adaptation method as claimed in claim 1, what the method for described transmission and reception was used is not confirm formula information transfer service pattern (UITS), has only a key element LAPP at the 2nd layer, does not have flow control, does not also carry out any affirmation formula operation.

Advantage of the present invention with respect to existing RFC1619, has following innovation:

(1) at present more external manufacturers develop according to the PPP over PDH (being RFC1619) that internet engineering duty group (english abbreviation IETF) proposes, with regard to RFC1619 itself, link layer has PPP (point-to-point protocol) and two kinds of agreements of HDLC (high-level data link rules), more complicated, hardware spending was too big when it was used for the above speed of per second 140 megabits, the present invention only adopts a LAPP key element by contrast, its complexity and HDLC are suitable, saved " LCP (english abbreviation LCP) " and magic number (English the is expressed as Magic Number) mechanism of the complexity among the PPP, the expense of used protocol adaptation reduces greatly;

(2) RFC1619 does not still support IP over PDH at present, when the application of PPP over PDH is to Internet marginal layer and core layer like this, does not have the standard support, and the present invention can support fully to Lower Order Virtual Container by contrast, and is both simple, complete again;

When (3) adopting RFC1619, because PPP need connect, the default value of retransmission timer is decided to be 3 seconds in PPP.For high-speed link, too blunt, use for concrete engineering, should require all to support to the speed range of per second 140 megabits from per second 2 megabits, so the value of retransmission timer should be determined according to the time delay that circuit comes and goes, these are not all made stipulations in RFC1619, thereby when the apparatus interconnection of different manufacturers uncertainty may appear, the present invention adopts and does not confirm formula information transfer service mode by contrast, do not need to connect, also do not need to use retransmission timer, the uncertainty of communicating by letter between any peer-entities can not occur, the application of the speed range from per second 2 megabits to per second 140 megabits is all supported;

(4) about filling the use of function, the information field of PPP generally will be filled into maximum receive unit (english abbreviation MRU, general provision is 1500 bytes on internet), for general internet packet, as the application of browser (English is expressed as WWW) online (this kind application account for 75% that whole internet uses), packet length is average out to 330 bytes, average like this having an appointment 350% is to flog a dead horse, efficient is very low: in addition, it is information field that this filling field also needs a function which is distinguished at receiving terminal, which is to fill field, this has increased processing expenditure again, the present invention is irrelevant with the filling function by contrast, uses for any internet, does not have this idle work;

(5) the present invention has considered Ipv4 that is using at present and the Ipv6 that is about to use, supports to have good real world applications characteristics and extensibility in the future with unified LAPP mechanism;

Generally, the present invention is with very letter refining, mode with cheapness solves the protocol adaptation of internet to the PDH telecommunication transmission efficiently, " point-to-point protocol (english abbreviation PPP) and two key elements of high-level data chain rules (english abbreviation HDLC) are supported internet protocol the 4th edition (english abbreviation Ipv4) and the application of internet protocol sixth version (english abbreviation Ipv6) on PDH with key element replacement of PDH Link Access Procedure.

Description of drawings

Fig. 1, conception schematic diagram proposed by the invention

Fig. 2, the present invention transmit the schematic diagram of PDH passage with PDH photoelectricity transmission section

Fig. 3, the present invention transmit the schematic diagram of PDH passage with SDH photoelectricity transmission section

Fig. 4, the protocol stack arrangement example schematic of networking of the present invention

Fig. 5, the UNE of internet protocol proposed by the invention and PDH (Pseudo-synchronous Digital Hierarchy) PDH are for example

Fig. 6, network layer proposed by the invention, the primitive graph of a relation between link layer and the physical layer

Fig. 7, the present invention uses conception figure in national IP over SDH (containing PDH in the SDH passage) core layer networking

Fig. 8, the present invention is in IP over SDH (containing PDH in the SDH passage) core layer networking application conception inside the province

Embodiment

Below, embodiments of the invention are described with reference to the accompanying drawings.

Imagination proposed by the invention is mainly used in the core switch router, the edge switch router, and based on the high low-end switch of packet switch, user side integrated access equipment and interconnecting and interworking equipment relevant etc. with internet.Application framework of the present invention is seen Fig. 1, it is conception schematic diagram proposed by the invention, wherein IPv6 represents the internet protocol sixth version, IPv4 represents internet protocol the 4th edition, SAPI represents the service access point identifier, and network layer adopts internet protocol (IP) (comprising Ipv4 and IPv6), and link layer adopts PDH Link Access Procedure (english abbreviation LAPP), physical layer adopts PDH (Pseudo-synchronous Digital Hierarchy) (PDH), mainly comprises all kinds of high-orders and Lower Order Virtual Container.In this framework, the 3rd layer of service access point that provides of the 2nd course has two, respectively for using based on the packet of IPV4 with based on the packet of IPV6.Their service access point identifier (SAPI) is respectively a decimal number " 4 " and " 6 ".Whole protocol Data Unit in the layer 3 IP bag (english abbreviation PDU), " version field " (English Version), professional (the English Differentiated Services) code-point of segmentation or IPv4 business type field (english abbreviation TOS), when sending as 2 layers of the parameter maps to the of primitive.At the 2nd layer, the information field of the PDU that shines upon as LAPP; The version field of shining upon as service access point identifier (english abbreviation SAPI), and is transferred to the address field of LAPP; The professional code-point of the segmentation of shining upon or IPv4 business type field as a kind of foundation, control formation algorithm.Do not confirm formula information transfer service (UITS) the 2nd layer of employing, it and the 1st layer are also mutual with primitive and parameter by corresponding service access point.Fig. 2 is the schematic diagram of the present invention with PDH photoelectricity transmission section transmission PDH passage, wherein below LAPP, the LAPP frame is put into the PDH passage, transmit according to the regenerator section of PDH and the order of photoelectricity transmission section again, then extract the LAPP frame by opposite order at receiving terminal; Fig. 3 is the schematic diagram of the present invention with SDH photoelectricity transmission section transmission PDH passage, the LAPP frame is put into the PDH passage, again the PDH passage is shone upon into Lower Order Virtual Container or higher order virtual container, again according to the SDH multiplexing section, the order of regenerator section and photoelectricity transmission section transmits, and then extracts the LAPP frame by opposite order at receiving terminal; The protocol stack arrangement example schematic of Fig. 4 networking of the present invention, its expression local area network (LAN) inserts the inlet side of IP over PDH net and the protocol stack arrangement that goes out to hold each node of gateway, LLC presentation logic controlling links sublayer wherein, MAC represents MAC sublayer, PDH represents PDH (Pseudo-synchronous Digital Hierarchy), LAN represents local area network (LAN), IPv4 represents internet protocol the 4th edition, IPv6 represents the internet protocol sixth version, TCP represents transmission control protocol, UDP represents User Datagram Protoco (UDP), IP represents internet protocol (general address), and the fusion of " IP over PDH " expression internet protocol and PDH (Pseudo-synchronous Digital Hierarchy) is at the gateway place, be furnished with PDH and MAC two class physical interfaces simultaneously, and that network layer remains Ipv4/Ipv6 is constant.Fig. 5 be internet protocol proposed by the invention and PDH (Pseudo-synchronous Digital Hierarchy) PDH UNE for example, wherein, solid line represents to adopt between the node PDH (Pseudo-synchronous Digital Hierarchy) physical connection, dotted line represents to intend between the node packet exchange of employing, black node is represented the network boundary node, play the gateway effect, Bai Jiedian represents network backbone node, it can overlook IP over PDH network from the angle of node, here it must be emphasized that, in IP over PDH net, only need be on same link the identical (upper-layer protocol certainly of two physical interface speed of equity with physical index, also mutually equal as LAPP with IP), so the IP over pdh physical interface of various different rates can be arranged on each link in the net.What Fig. 6 described is network layer proposed by the invention, primitive graph of a relation between link layer and the physical layer, wherein LAPP provides two service access points, its identifier value (SAPI) equals decimal number " 4 " use for Ipv4, its identifier value (SAPI) equals decimal number " 6 " for Ipv6 usefulness, send out packet to link layer from network layer, use " DL-UNACK-DATA request " primitive, receive packet to network layer from link layer, use " DL-UNACK-DATA indication " primitive; Between link layer and physical layer, from the link layer to the physical layer, use " PH-DATA request " primitive link setup, use " PH-DATA indication " primitive then to represent to send out the link setup indication to link layer by physical layer.Send out packet to physical layer from link layer, use " PH-DATA request " primitive, receive packet to link layer, use " PH-DATA indication " primitive from physical layer.Fig. 7 is that the present invention uses conception figure in national IP over SDH core layer networking, wherein black circle is represented the core route exchange device based on IP over SDH equipment, small rectangular block is represented SDH existing on the present national backbone network or WDM transmission equipment, this example is that existing resource is given an example the existing transmission network management of the computer representation at white interface with present Chinese 8 * 8 SDH or wavelength division multiplexing (english abbreviation WDM) trunk transit network; After each node city employing has the core switch router of IP over SDH interface, can form a packet switch core net that extends in all direction, the computer representation at black interface is about to the webmaster of the core switch router net of layout, in these links, also can adopt IP over PDH.Fig. 8 is that the present invention is in IP over SDH core layer networking application conception inside the province, wherein black circle is represented the core route exchange device based on IP over SDH equipment, the Xiao Bai circle is represented the branch line route exchange device based on IP over SDH equipment, REG is a regenerative repeater, ADM is an add-drop multiplexer, and LAN is a local area network (LAN); The each province is mostly with the SDH ring-shaped network at present, and this example is that existing resource is given an example with present Chinese each province SDH looped network or wavelength-division multiplex system (english abbreviation WDM) trunk transit network; Each districts and cities node city inside the province adopt have the core switch router of IP over SDH interface after, can form one in the packet switch core net that extends in all direction inside the province, in these links, can adopt IP over PDH equally.

Claims (5)

1. an adaptation method that is used for internet and PDH (Pseudo-synchronous Digital Hierarchy) fusion comprises the following steps:

Receive packet from the network layer device of internet, the type of recognition data bag produces the service access point identifier according to the type of discerning, and described packet is converted to first kind frame and reflects the segmentation business code-point that sends priority; Described first kind frame is packaged into the frame format that comprises beginning flag, address field, control field, information field, Frame Check Sequence field and termination flag, to form the second class frame; With the second class frame in bit-oriented mode with to segment on the cascade channel that transmission priority mapping that professional code-point reflected forms to single PDH passage or by a plurality of PDH passages; Frame Check Sequence calculate finish after, transmit leg is checked the entire frame content between two flag of frame, will insert " 0 " automatically following closely when whenever running into five continuous " 1 " sequences; The recipient, before Frame Check Sequence calculates,, will be abandoned automatically in any " 0 " afterwards, five continuous " 1 ".

2. adaptation method as claimed in claim 1, the service access point identifier of the described second class frame is corresponding to address field or be inserted on two the information field bytes of the most close control field.

3. adaptation method as claimed in claim 1, described cascade channel is by the PDH passage of two or more same rates with the path, be passage A1, A2, form to An, the bit-order of mapping is: the 1st bit of passage A1, the 1st bit of passage A2, the 1st bit of passage A3 is to the 1st bit of passage An, the 2nd bit of passage A1, the 2nd bit of passage A2, the 2nd bit of passage A3 is to the 2nd bit of passage An, N bit to passage A1, the N bit of passage A2, the N bit of passage A3 is to the N bit of passage An, and the maximum number bits of every passage is the basic frame length N0 of the single PDH passage of ITU-TG.704 defined.

4. adaptation method as claimed in claim 1, the virtual container of the physical layer of described PDH (Pseudo-synchronous Digital Hierarchy) PDH passage and bandwidth, payload parameter are:

Its speed of E1 is that 2048 kilobits/second are encoded to HDB3

Its speed of E3 is that 34368 kilobits/second are encoded to HDB3

Its speed of E4 is that 139264 kilobits/second are encoded to CMI

Its speed of T1 is that 1544 kilobits/second are encoded to AMI or B8ZS

Its speed of T2 is that 6312 kilobits/second are encoded to AMI or B6ZS or B8ZS

Its speed of T3 is that 44736 kilobits/second are encoded to B3ZS

5. adaptation method as claimed in claim 1, use be not confirm formula information transfer service pattern, have only a key element PDH (Pseudo-synchronous Digital Hierarchy) Link Access Procedure at the 2nd layer, do not have flow control, do not carry out the operation of any affirmation formula yet.

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