CN1688142A - VoIP remote communication method of SCN network and IP network combination - Google Patents

Abstract

A VoIP remote communication method combining SCN and IP networks uses a media information route method, which specializes the router to a media router, utilizes two kinds of network channels, SCN and IP to set up VoIP remote connection and instantly alters the route between the two channels based on the QoS measurement result to the IP network to realize remote voice communication. When IP can meet the QoS requirement, IP is used to communicate, if not, SCN network can be used instead temporarily until the IP can meet the needs again to ensure the least communication cost.

Description

The VoIP remote communication method that SCN net and IP network combine

Technical field

The present invention relates to a kind of VoIP remote communication method.

Background technology

Voip technology is among the NGN (Next Generation Network), replaces the telecommunications network voice service, solves the important technology of online Speech Communication.Can work well in the VoIP of LAN scope communication at present, not need call rate, QoS is also fine.

Yet the VoIP communication of crossing over remote two LAN scopes does not have way practical, that can extensively not promote.Remote VoIP communicates by letter as shown in Figure 1 between two LAN, by router R and long-range the connecting to form between them.Long-range connection can be waited and be realized by public Internet, special-purpose WAN.But connect very difficult guaranteed qos by public Internet, high by the WAN connection charge of special use, the general user can not select.

Summary of the invention

The problem that the present invention solves is: in the VoIP communication system, need under the situation of many speech path between two LAN, the advantage that performance IP network cost of the phone call is cheap and SCN (Switched Circuit Network) has QoS to guarantee, the two combines and uses simultaneously, realize remote I P Speech Communication, both satisfied the QoS reasonable request, and can make cost of the phone call low again.

As shown in Figure 2, the invention provides a kind of medium method for routing, the router of adopting said method is called media router (Media Router is called for short MR) in the present invention.Comparison diagram 2 (a) and (b), the result that router feature is becomed privileged has replaced ordinary router R with MR, and between two routers except the IP path, increased the SCN path.Must respectively there be a MR to connect two long-range LAN between two A sides, guard station and the B side.

A MR has 3 kinds of interfaces: connect Ethernet interface, SCN interface and the remote I P network interface of local network, wherein back two kinds of interfaces can be a plurality of.The SCN interface comprises two kinds of PSTN analog interface and ISDN digital interfaces again, and remote I P network interface can be adsl interface, Ethernet interface etc.

The functional block diagram of MR as shown in Figure 3, its major function comprises that the SCN of the getable standard of existing known technology institute drives, the IP Intranet drives, the IP outer net drives (brief note is SCN-Drv, I-Drv, E-Drv respectively), also comprise the special functional module that the present invention designs: SCN path management, IP path management, QoS measure and route control, and each functions of modules is as follows:

SCN path management module: safeguard a channel occupancy state table of SCN path, state table is designated as SCN-Table.

IP path management module: safeguard a channel occupancy state table of IP path, state table is designated as IP-Table.

QoS measurement module: set up a RTP who is used to measure (Real-time Transport Protocol) at IP network and connect, estimate the QoS of IP network.This RTP connection is designated as E-Link, and the QoS estimated result is designated as vQoS.

Routing module control:

1, at each time beat, according to vQoS, between SCN path and IP network path, shift connection back and forth, the algorithm of finishing this function is designated as C-Alg.Shifting the process that connects is transparent to the user, the imperceptible transfer connecting moves of user.

2, be connected with cancelling according to the newly-built connection of user's request.

MR utilizes SCN net and two kinds of approach of IP network, realizes remote voice communication.Use IP network to communicate when IP network can satisfy qos requirement, just use the SCN net in the time of can not satisfying qos requirement temporarily, the communication quality improvement when IP network re-uses IP network in the time of can satisfying qos requirement and communicates.

Below the implementation method and the MR work principle of these 4 functions of explanation at first illustrate basic conception.

1, physical connection: be meant the long range path that MR sets up, it monopolizes certain line resource, certain expense cost (physical connection is minimum Charging Detail Record unit) is arranged, a B channel such as ISDN,, an ADSL line attachment,, a PSTN analog line, an ethernet line etc. all is a physical connection.

2, connect: refering in particular to the logic channel between two MR of two guard stations, is exactly that a voice speech channel connects.For IP network is exactly that RTP connects, and is exactly 8 of the B channel bearing G.729 one of voice flows for the ISDN net.Can carry one or more connections on the physical connection.

Unless stated otherwise, one connects or physical connection is the two-way connection that comprises both direction.

3, service quality QoS: by one group of parametric representation, characterize the present communication quality of channel, or the user's communications quality requirement.For the statement of channel quality, according to RFC 2205 and the RFC2216 of IETF, the qos parameter of IP network CBR (Constant Bit Rate) service has: average delay, minimal time delay, maximum jitter and packet loss.For VoIP, after the storage buffering, the qos parameter of equivalence becomes time dependent two functions: current time delay delay (t) and present packet loss loss (t).Be without loss of generality, the present invention specifically becomes vector to the qos parameter of channel

QoS(t)＝[delay(t)，loss(t)]

Have a plurality of users and communicate by letter simultaneously on the communication line between two MR, each user respectively has the QoS demand r of oneself, and a plurality of r have constituted the QoS demand total to communication line, and this total QoS demand is represented the telex network demand of t constantly with R (t) expression.

R(t)＝[r1，r2，…，rm]

Wherein ri is i user's a quality requirement, and it is a vector

ri＝[delay[i]，loss[i]]

Delay[i] and loss[i] be respectively the maximum delay and the maximum packet loss of i customer requirements.

The time variation of R (t) is the arrival of some ri and leaves away, and comprises the variation of number of users and the variation of qos requirement.

Introduce the process of utilizing MR to realize the VoIP telecommunication that SCN net and IP network combine below.

SCN path management module receives and transmission RTP packet by calling SCN-Drv, finishes the communication function of the connection of having set up.On the other hand, this module can newly-builtly be connected with cancelling according to the requirement of routing module control, when newly-built connection, SCN path management module is responsible for setting up new physical connection under the condition that physical connection has taken, otherwise, when cancelling connection, have under the condition of an above physical connection free time, SCN path management module is responsible for cancelling no physical connection.SCN-Drv is responsible for the RTP packet is converted to the data of physical channel, is transferred to the opposite end, and the opposite end converts the RTP packet more in the other direction to.The information of each connection is recorded among the SCN-Table, and is as shown in table 1, and each row is represented a connection, three contents is arranged: the QoS of connection ID, requirement, the physical channel numbers that takies in the connection." connection ID " is the sign of this connection, is made of the Dest (purpose) of initial IP packet and the IP-port (IP address-port numbers) of Source (source); " QoS of requirement " is the QoS of this RTP connection request, comprises delay and loss; " physical channel numbers that takies " is this physical channel numbers that connects current place.

Sequence number	Connection ID	The QoS delay that requires, and loss (millisecond, x%)	The physical channel numbers that takies
				????0	(IP-port by original Dest and Source constitutes)	????30，1％	????1
????1	The same	????100，0.5％	????1
				????2	The same	????20，1％	????1
????3	The same	????30，1％	????1
				????4	The same	????20，2％	????1
????5	The same	????50，1％	????1

Table 1

IP path management module receives and transmission RTP packet by calling E-Drv, finishes the communication function of the connection of having set up.Similar with the ISDN path, the IP path also is responsible for the newly-built of physical connection and is cancelled, and needs channel occupancy state table of design, and is as shown in table 2.Each row is represented a connection, three contents is arranged: the QoS of connection ID, requirement, the physical channel numbers that takies in the connection; " connection ID " is the sign of this connection, is made of the Dest of initial IP packet and the IP-port of Source; " QoS of requirement " is the QoS of this RTP connection request, comprises delay and loss; The sequence number of the physical connection of " physical channel numbers that takies " expression IP network.The physical connection of IP network can insert by ADSL, Ethernet inserts and realizes etc.

Sequence number	Connection ID	The QoS delay that requires, and loss (millisecond, x%)	The physical channel numbers that takies
				?0	(IP-port by original Dest and Source constitutes)	????100，1％	2
?1	The same	????150，0.5％	2
				?2	The same	????75，1％	2
?3	The same	????75，1％	2
				?4	The same	????75，2％	2
?5	The same	????75，1％	2

Table 2

The IP path is the packet switch path, and voice connect logicality just, do not have physical location and ordinal relation each other, so it is simple that its channel space takies figure, only with the situation that takies of a counter records physical channel, the control channel overload gets final product each physical connection, as shown in Figure 5.This figure is an example with the ADSL access, the ADSL message transmission rate of extensive use now is 512Kb/S, the message transmission rate that adopts G.729 every connection of compression algorithm is 8kb/s, considers RTP packet header expense, an open ended linking number of physical channel (being designated as Nch_ADSL)=50.The current linking number (being designated as Counti) of a physical channel must satisfy: Counti＜=Nch_ADSL.

The RTP bag that I-Drv is responsible for IP Intranet direction receives and sends, and is common network-driven, does not repeat them here.

The QoS measurement module is set up E-Link between A side and B side when system initialization, measure the QoS of IP network in real time, outcome record in variable vQoS.Set up process that measure R TP connects and connect equally with setting up common RTP, it is a two-way connection, qos parameter that can the independent estimations both direction.The method prior art of estimating QoS can obtain, and does not repeat them here.

Routing module control can dynamically be adjusted route, dynamic routing algorithm C-Alg is beat Tclk (span of Tclk is between 1 second to 10 seconds) at regular intervals, each qos requirement that is connected of value and SCN-Table and IP-Table of vQoS is compared, the connection that QoS among the SCN-Table is lower than vQoS moves to the IP path, the connection that QoS is higher than vQoS among the IP-Table moves to the SCN path, and the algorithm realization flow as shown in Figure 6

Function newly-built, that cancel connection that routing module control also has.If new customer requirements communication is arranged, MR just sets up new connection, according to qos requirement that increases the user newly and vQoS, by calling E-Drv or SCN-Drv, increases connection at IP path or SCN path, and revises SCN-Table or IP-Table, increases delegation.In the time of need cancelling a connection, by calling E-Drv or SCN-Drv, deletion is connected with the SCN path is no at the IP path, and the corresponding row among deletion SCN-Table or the IP-Table.

The foundation of SCN physical connection needs 1 second to 30 seconds time usually, and this speed far can not satisfy the rate request that media data is dynamically adjusted route.For solving this contradiction, the present invention adopts the pre-established measure of a kind of physical connection.With the ISDN access is example, introduce this method, and another kind of access way----PSTN access way and ISDN access way are similar, difference is that each physical connection of PSTN access way can only be carried 1 connection, and the ISDN access way can be carried 8 connections (when G.729 encoding), so the PSTN access way does not repeat them here, only further specify the pre-established measure of SCN physical connection with regard to the ISDN situation.

Fig. 4 (a) is the channel space figure that (the SCN network) ISDN inserts, and n B channel configuration arranged among the figure, and a physical connection takies a B channel, and each B channel can carry 8 connections.Defining constant Nr_ISDN is the minimum ready linking number of reservation, No_ISDN is current actual linking number, Nc_ISDN is the ISDN physical connection number of current needs, and SCN path management module is come in time newly-built according to the situation of current connection among the SCN-Table and Nr_ISDN and cancelled physical connection.Nc_ISDN calculates according to following formula:

Nc_ISDN=[(No_ISDN+Nr_ISDN)/8] (formula 1)

Symbol wherein

Expression more than or equal to integer operation.

In a word, according to above method, always there be Nr_ISDN the ready connection of reservation to use immediately, and need not set up new physical connection at once.According to application demand, Nr_ISDN is desirable 1,2,3 ....

Fig. 4 (b) and (c) in Nr_ISDN=2, the connection used of " taking " representative, " reservations " representative have been set up but have not been had the ready connection of reservation of use.Reserving connection can use immediately, has eliminated physical connection and has set up influence slowly.Fig. 4 (b) increases a connection again and just becomes in Fig. 4 (c) state, and the former takies 1 physical connection, and the latter takies 2 physical connections.

If the ADSL physical connection is not 24 hours mode of communicating of monthly payment, and it is longer to set up the elapsed time of physical connection, can use to set up to reserve with the same method of ISDN to be connected.

In order to satisfy formula (1), might need during newly-built the connection increases new physical connection, cancels when connecting and might connect by deletion of physically.The process of cancelling connection is comparatively complicated, occurs the situation of " fragment ", when the actual physics linking number

During＜Nc_ISDN, need to merge two or more physical connections.

The present invention combines the SCN net with IP network, realized the long-range connection of VoIP, by instantaneous change route transmission speech between two kinds of nets, utilize the cheap IP network of communication cost as far as possible, in the time can not satisfying qos requirement, use the SCN net to come guaranteed qos, reached the minimum effect of communication cost under the condition of guaranteed qos.

Insert with ADSL between MR and IP network, this method has very high practicality.Under typical condition, there was 60% above time to converse, and can saves 90% cost of the phone call, and can guarantee the desired QoS that converses in one day 24 hours without Circuit Switching Network.

Description of drawings

Fig. 1 is a remote VoIP communication scheme between two LAN

Fig. 2 is the long-range method of attachment block diagram of SCN and IP network combination;

Wherein:

Figure (a) is the theory diagram that the method for utilization ordinary router realizes;

Figure (b) is the theory diagram that adopts the media data method for routing realization of the present invention's design;

Fig. 3 is the functional block diagram of MR;

Fig. 4 is the channel occupancy schematic diagram of ISDN;

Wherein:

Figure (a) is 8 * n G.729 voice flow signal of n B channel and carrying thereof.The capacity of a B channel of the space representation between solid line up and down, the capacity of the voice channel of space representation between dotted line;

Figure (b) only takies a B channel signal, also has 2 to reserve ready connection surplus, then not newly-built B channel;

Figure (c) takies the signal of 2 B channels, and B1 has only 1 to reserve ready connection surplus, then sets up new B channel, guarantees to have that to reserve ready connection more than 2 available, and this situation is actual to be had 9 to reserve ready connection surpluses standby at once;

Fig. 5 is the channel occupancy Count of Status figure of ADSL; Channel occupancy Count of Status figure when this figure is depicted as m ADSL physical connection;

Fig. 6 is the C-Alg algorithm flow chart.

Claims (7)

1. the VoIP remote communication method that combines of SCN net and IP network, it is characterized in that, at media information, provide a kind of medium method for routing,, utilize two kinds of network paths of SCN net and IP network to set up that VoIP is long-range to be connected the special media router that turns to of router, according to QoS measurement result to IP network, instantaneous change route between two kinds of network channels, realize remote voice communication: when IP network can satisfy certain user's qos requirement, this user's communications used the IP network path to carry out; In the time of can not satisfying user's qos requirement, this user's communications is used SCN Netcom road temporarily and is carried out, and when the communication quality of IP network improves, re-uses the IP network path in the time of can satisfying this user's qos requirement and communicates;

2. medium method for routing as claimed in claim 1, it is characterized in that, it is fast and set up the slow-footed contradiction of physical connection to take the pre-established measure of physical connection to solve the speed of instantaneous change route: defining constant Nr_ISDN is the minimum ready linking number of reservation, No_ISDN is current actual linking number, Nc_ISDN is the physical connection number of the ISDN of current needs, and Nc_ISDN calculates according to following formula:

Symbol wherein

Expression more than or equal to integer operation, can guarantee always to have Nr_ISDN to reserve ready connection and can use immediately like this, and need not set up new physical connection at once;

3. media router as claimed in claim 1 is characterized in that, comprises four special functional modules: SCN path management, IP path management, QoS measure and route control;

4. media router as claimed in claim 3, it is characterized in that, SCN path management module receives and transmission RTP packet by calling SCN-Drv, and the number of connection of the current carrying of each physical channel of monitor log, safeguards a channel occupancy state table of SCN path;

5. media router as claimed in claim 3, it is characterized in that, IP path management module receives and transmission RTP packet by calling E-Drv, and the number of connection of the current carrying of each physical connection of monitor log, safeguards a channel occupancy state table of IP path;

6. media router as claimed in claim 3 is characterized in that, during QoS measurement module system initialization, sets up E-Link between A side and B side, measures the QoS of IP network in real time, outcome record in variable vQoS;

7. media router as claimed in claim 3, it is characterized in that, routing module control adopts dynamic routing algorithm C-Alg beat Tclk at regular intervals, each qos requirement that is connected of value and SCN-Table and IP-Table of vQoS is compared, the connection that QoS among the SCN-Table is lower than vQoS moves to the IP path, the connection that QoS is higher than vQoS among the IP-Table moves to the SCN path, and the span of Tclk is between 1 second to 10 seconds.

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