CN101119270A - Network boundary treatment method - Google Patents
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- CN101119270A CN101119270A CNA2007100532268A CN200710053226A CN101119270A CN 101119270 A CN101119270 A CN 101119270A CN A2007100532268 A CNA2007100532268 A CN A2007100532268A CN 200710053226 A CN200710053226 A CN 200710053226A CN 101119270 A CN101119270 A CN 101119270A
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Abstract
The present invention discloses a method of network boundary disposal, which comprises: a signaling channel is established between a first SIP terminal and a second SIP terminal; and a media cannel is established between the first SIP terminal and the second SIP terminal. The network boundary disposal method provided by the present invention can realize that a conversation edge controller is adopted to conduct firewall or NAT crossing with no change to the prior network rack. The method is a network boundary disposal mechanism which is widely used for the network systems based on SIP such as the 3G core network and the next generation network.
Description
Technical field
The present invention relates to communication technical field, relate in particular to a kind of dialogue-based startup agreement (SessionInitiation Protocol, network boundary treatment method SIP).
Background technology
Along with the deployment that begins of 3G network, even accumulated certain networking and operation experience, but the standard of 3G network is still perfect in the exhibition of not stopping paying out, and experiences six stages of R99 to R7 at present.But penetrate and the border issue of topology hiding still exists such as privately owned address transition, fire compartment wall.
At first, the 3G core net wishes to be the more users service, must support existing GPRS (General Packet Radio Service, GPRS)/universal mobile telecommunications system (UniversalMobile Telecommunication System, UMTS) user's access, WLAN (wireless local area network) (WirelessLAN, WLAN) user inserts, or even fixed-line subscriber.There is very big otherness between these different network organization forms, needs a kind of mechanism to shield this otherness, realize with the 3G network being the heterogeneous network fusion of core.
Secondly, deployment along with the 3G core net, the product of each standard agreement of 3G core net occurs in succession, the 3G core net network of in addition now having disposed, next generation network (Next Generation Network, NGN) network and conventional telecommunication network, must resolve communication issue, just can accomplish interconnection and interflow with existing network from different operators foreign lands.
At last, concerning operator, during with the intercommunication of other operators, do not obtained, need to hide the network topology of operator by the rival in order to protect its business sensitive information; Concerning the user, when its relevant message related to calls enters owner's network, must carry real subscriber identity information, and when message enters into the visited network operator network, these real informations must be removed again.Certainly, when reaching this purpose, also can introduce new privately owned address transition and fire compartment wall and pass problem.
Border issue for main existence at present has following several:
Network address mapping is because IP address anxiety at first, a lot of enterprises and mechanism organize the formation local area network (LAN) with the main frame of inside, these main frames are by being located at gateway and the external network communication on the network boundary, finish network address translation during communication, be network address translation (Network Address Translation, NAT) function.The IP address that is about to each LAN node becomes public network IP address and port with port translation, vice versa.And in the 3G core net.On the other hand, even if the IPV6 epoch, all terminals all have independent IP, but terminal can not directly enter other carrier networks, simultaneously between the operator in order to guarantee trade secret, usually with hiding its real address of the terminal of own service, other operators are seen is address after the address transition.So map addresses also still exists in IPV6.So need carry out the NAT mapping on 3G core net border on the one hand, need under the prerequisite of NAT mapping, guarantee the accessibility of communication on the one hand again.
Fire compartment wall is a kind of passive Defense Technology Journal, is positioned at the border of network, carries out access control policy between two networks, prevents the unauthorized access of external network to inner information resources, also can stop customizing messages internally network illegally exported.Generally speaking, fire compartment wall can work at all levels on the network layer.Packet filter firewall is common fire compartment wall, all possesses this function on the general router.Packet filter firewall operates mainly in network layer, determines whether and the IP grouping will be transmitted according to the information in each packets headers, strengthens fail safe with this.In theory, packet filter firewall can be configured to judge according to any part of protocol header, but most of filters are configured to only filter most important data field.
In the 3G core net, adopt caller incoming call mode (unsolicited incoming calls), and the calling party can't predict called network condition, if the called fire compartment wall back that is in, even a port of opening on the fire compartment wall comes special receipt of call signaling, voice and video passage after call setup is finished is owing to being dynamic assignment, so may thereby can't transmit owing to the former of fire compartment wall.That is to say in order to allow voice and video communication will have to revise firewall configuration and support two-way communication arbitrarily, this change is unacceptable.
Border issue for the 3G core net does not have a unified solution at present, is made up of the functional entity of a lot of dispersions, finishes different tasks respectively.Such as being positioned at User Network Interface (UserNetwork Interface, UNI) borderline bag data gateway (Packet Data Gateway, PDG) be responsible for being treated to the information security in tunnel between WLAN user terminal and the core net, BAS Broadband Access Server (Broadband Access Server, BAS) then be responsible for fixed network access 3G core net service is provided, logical functional entity Breakout Gateway Control Function (Breakout Gateway Control Function, BGCF), MGCF (Media Gateway Control Function, MGCF), Multimedia Resource Function (Multimedia Resource Function, MRF) and media gateway (MediaGateway, MGW) then be responsible between the carrier network, perhaps between the inner heterogeneous networks of operator, Network-to-Network Interface (Network Network Interface, NNI) functions such as borderline protocol conversion and media transcoding.But on these functional unit functions very big repeatability is arranged, when function changed, the peripheral interface that relates to was more, was unfavorable for that the isomery of 3G network merges and upgrading.
The Internet engineering duty group (Internet Engineering Task Force, IETF) employing session margin control (Session Board Controller has been proposed, SBC) solve map addresses and fire compartment wall penetration problem, but it is primarily aimed at flexible exchanging network, especially the penetration problem in the enterprise network, but only defined relevant functional requirement, do not elaborated its realization mechanism.And also there is the diverse network border issue in the various network systems based on SIP such as NGN, multimedia enterprise communication.
Summary of the invention
To the objective of the invention is that privately owned address transition, fire compartment wall that prior art exists penetrate and the border issue of topology hiding in order solving, and a kind of network boundary treatment method to be provided, use SBC to carry out fire compartment wall/NAT and pass through.
To achieve these goals, the invention provides a kind of network boundary treatment method, comprising:
Set up signalling path between first sip terminal and second sip terminal; And
Set up media channel between described first sip terminal and second sip terminal.
Further, setting up signalling path between described first sip terminal and second sip terminal is:
Described first sip terminal or second sip terminal send first log-on message to the first or second session margin control of its desire registration; The described first or second session margin control is made amendment to described first log-on message, and sends it to sip server; Sip server requires described first sip terminal or second sip terminal to authenticate; Described first sip terminal or second sip terminal send second registration message to described session margin control; And described first or second the session margin control described second registration message is handled, and second registration message is sent to sip server, authentication is by succeeding in registration.After succeeding in registration, first sip terminal or second sip terminal still need the first or second session margin control timed sending log-on message to its registration, to keep the validity of signalling path.
Further, the described first or second session margin control to described first log-on message make amendment into:
Contact (Contact) address information that described session margin control is revised in first registration message is the IP address and the port of described session margin control; And the sip server address that hyperlink request (url) address in described first registration message is modified as the configuration of session margin control.
Further, the described first or second session margin control is treated to described second registration message:
Described session margin control is kept at the address of described first sip terminal or second sip terminal and number and the address shone upon in the address digit correspondence table on NAT, contact (Contact) address information of revising in second registration message is the IP address and the port of described session margin control; And the sip server address that the hyperlink request address in described second registration message is modified as the configuration of session margin control.
Further, setting up media channel between described first sip terminal and second sip terminal is:
First sip terminal sends call request information to the first session margin control of its registration, carries out the address change during through a NAT;
The described first session margin control is transmitted to described sip server after described call request message is handled;
The second session margin control is accepted the described call request message that described sip server sends, and after described call request message handled, sends to described second sip terminal by protocol stack;
After the described call request message that the 2nd NAT will receive is changed, be transmitted to described second sip terminal;
Described second sip terminal is replied response message to the second session margin control, and the first session margin control handled and return to by the second session margin control to it, and the first session margin control is handled it and returned to described first sip terminal; And
First sip terminal is replied acknowledge message by the first session margin control and the second session margin control and is given second sip terminal.
Further, network boundary treatment method also comprises: first sip terminal and second sip terminal are reported agreement (User Data Protocol to the described local user data of the first session margin control and the configuration of the second session margin control respectively, UDP) port sends the quiet bag of voice (RTP) first, and burrow at a NAT (NAT1) and the 2nd NAT (NAT2), the first session margin control and the second session margin control carry out respective handling and transmit quiet bag RTP after receiving the quiet RTP bag of voice, to finish the foundation of media channel.
Further, the described first session margin control is treated to described call request message:
The first session margin control carries out information screen and also will distribute the information of local udp port to be added in the sip message body of described call request message for the transmission of Media Stream distributes local udp port; And
The first session margin control is revised the hyperlink request address in the described request message related to calls, route, contact address, message body length and the message body SDP part of process.
Further, the described second session margin control is treated to described call request message:
It is the local udp port that distributes of the transmission of Media Stream and for the transmission of Media Stream distributes local udp port that the described second session margin control is preserved the first session margin control in the sip message body of described call request message, and will distribute the information of local udp port to be added in the sip message body of described call request message;
Inquire about described address digit correspondence table, obtain the NAT address information of second sip terminal; And
Revise the hyperlink request address in the described request message related to calls, route, contact address, message body length and the message body SDP part of process.
Further, the described second session margin control is treated to described response message:
Revise the hyperlink request address in the described response message, route, contact address, message body length and the message body SDP part of process.
Further, the described first session margin control is treated to described response message:
It is the local udp port that the transmission of Media Stream distributes that the described first session margin control is preserved the second session margin control in the sip message body of described response message;
Inquire about described address digit correspondence table, obtain the NAT address information of first sip terminal; And
Revise the hyperlink request address (url) in the described response message, route, contact address, message body length and message body Session Description Protocol (Session Description Protocol, the SDP) part of process.
Further, the described first session margin control is treated to described acknowledge message:
Revise hyperlink request address, the route of process, contact address, message body length in the described acknowledge message.
Further, the described second session margin control is treated to described acknowledge message:
Inquire about described address digit correspondence table, obtain the NAT address information of second sip terminal; And
Revise hyperlink request address, the route of process, contact address, message body length in the described acknowledge message.
Further, after the described first session margin control or the second session margin control received the quiet bag of voice that first sip terminal and second sip terminal send for the first time, the respective handling of carrying out was:
When the described first session margin control or the second session margin control are to receive described RTP bag and RTP for the first time to transmit when not having respective items, the described first session margin control or the second session margin control are preserved described first sip terminal or second sip terminal and are mapped to RTP address information on a described NAT or the 2nd NAT, then the quiet bag of voice are transmitted.
Further, network boundary treatment method also comprises: the first session margin control or the second session margin control are set up the exchange of media routing index.
Further, the described first session margin control or the second session margin control are set up the exchange of media routing index and are:
The session control module of the described first session margin control or the second session margin control is the exchange of media information notification media session control module in the call proceeding, and indicates it to carry out the foundation of media channel;
The media session control module is protocol message H.248 with the exchange of media information translation;
(Signaling Access Gateway SAG) passes through H.248 protocol message notice medium control centre (Media Control Center, MCC) exchange of media information to the signaling IAD of integrated business access gateway;
MCC sets up the exchange of media routing index by exchange of media information and is kept in the transistroute index module.
Therefore, by network boundary treatment method provided by the invention, can realize using SBC to carry out fire compartment wall/NAT and pass through, need not the existing network framework is done any change, be a kind of network boundary treatment mechanism that generally is applicable to the various network systems based on SIP such as 3G core net, NGN.
Description of drawings
Fig. 1 sets up the block diagram of SBC server between 3G Access Network and core net for the embodiment of the invention;
Fig. 2 is that the SBC in the R6 version merges schematic diagram;
Fig. 3 is that the SBC in the R7 version merges schematic diagram;
Fig. 4 is that the SBC on the NNI interface merges schematic diagram;
Fig. 5 for network boundary treatment method of the present invention illustrate in related network configuration;
Fig. 6 is the flow chart of network boundary treatment method of the present invention;
Fig. 7 is the flow chart of the registration process (signalling path foundation) of user's sip terminal of the present invention;
Fig. 8 sets up the flow chart of media channel process for the present invention;
Call request (INVITE) message that first sip terminal of Fig. 9 User1 that preceding SBC1 receives for step S220 carries out sends;
Figure 10 is transmitted to the INVITE of sip server after handling through SBC1 after carrying out for step S220;
The flow chart that Figure 11 handles described call request message INVITE for the step S220 first session margin control;
Figure 12 is the flow chart that the second session margin control is handled INVITE;
Figure 13 sets up the flow chart of exchange of media routing index for SBC1 and SBC2.
Embodiment
The invention provides a kind of network boundary treatment method, when carrying out fire compartment wall/NAT, pass through by needs, at user's Intranet and the networking telephone (Voice over Internet Protocol, VoIP) set up the SBC server between the server, the embodiment of the invention is as shown in Figure 1 set up the SBC server between 3G Access Network and core net, the SBC server comprises SAG module and MCC module, the SAG module comprises Session Initiation Protocol stack and conversation control function, media session controlled function, user's route and information hidden function, and has H.428 protocol stack; By H.428 agreement SAG module and MCC module communication, the MCC module has the relaying road and the function of index, medium encryption and decryption is arranged and have rtp stack.By revising in the name server clauses and subclauses corresponding to call server (Call Server), give the user terminal that carries out the DNS inquiry with the IP address of SBC as the IP address response of call server, user terminal will mail to SBC with signaling but not general sip server.This process is transparent to the user, and to the VoIP terminal, the VoIP core net, corporate intranet, the network equipments such as fire compartment wall/NAT do not need to carry out any upgrading yet.
Be that the example explanation merges SBC with the core net to 3G with the 3G network border issue below.For SBC is fused in the 3G core net, dual mode is arranged, a kind of is to adopt independently SBC equipment, and changes or the interface in increasing the 3G core net, the second way is that existing equipment of the core network is transformed, and makes it to possess the function of SBC.For the accuracy of assurance function and interface definition, adopt SBC and existing equipment to merge.Its merge mainly show User Network Interface (User Network Interface, UNI) and Network-to-Network Interface (Network Network Interface is NNI) on two borders.
1, the SBC on the uni interface merges:
The 3G core net provides the control of corresponding session edge at different cut-in methods, relates to the overlapping functional unit of numerous functions.Introduce SBC equipment at R6 version and R7 version, can realize the integration of these functional entitys, and I-CSCF wherein also becomes the part of SBC in a way.Now R6 and R7 version are respectively described below:
SBC in the R6 version merges:
In the R6 version, SBC combines strategy decisive function unit (S-PDF) and Border Gateway Function unit (Access Border Gateway Function) function of acting on behalf of Session Control Unit (P-CSCF), separating, as shown in Figure 2.Wherein:
P-CSCF: be mainly used to control the safety of Access Network, set up resource needed in the process to the S-PDF request call.
S_PDF: realize the media strategy allocation strategy, and transmit resource request and give BGF, to obtain the resource of BGF.
Access Border Gateway Function: media relay function and hiding end-point addresses are provided, prevent that the behavior of stealing bandwidth from taking place.
SBC in the R7 version merges:
In the R7 version, SBC combines P-CSCF, resource access control function (A-RACS), S-PDF and Access Border Gateway Function function, as shown in Figure 3.Wherein:
P-CSCF: mainly finish SIP application level gateway functionality to IPv4 address translation and NAT Firewall Traversing.
S_PDF: can programming to Access Border Gateway Function, receiving media stream inserts.
A-RACS: in the R7 version, control access network resources.The expansion PDF that separates is divided into access-in resource and access control subsystem (A-RA CS), and A-RACS and PDF combine and are referred to as resource control subsystem (RACS).
Access Border Gateway Function: realize NAPT and Media Stream penetrating NAT/fire compartment wall.
2, the SBC on the NNI interface merges:
Before the R7 version, because the closure of core net, and agreement is unified, does not consider the border issue on the NNI basically, and the R7 version is introduced after the fixing access, has introduced I-BCF (boundary Control functional unit between net) and two equipment of I-BGF (borde gateway unit between net).SBC on the NNI interface need consider their fusion, with uni interface similarly is, I-CSCF is the part of SBC function to a certain degree.As shown in Figure 4.
Wherein the function of two equipment is as follows:
I-BCF:I-BCF is that control section possesses a) Transport Layer Security function; B) notice RACS calls out the resource requirement situation; C) the NAPT function among NAPT function and the BGF.
I-BGF:I-BGF is that to transmit that part possesses a) be the media relay function of concealed terminal node to medium; B) prevent that bandwidth from stealing; C) NAPT and NAT/ fire compartment wall penetrate function.
Fig. 5 is a related network configuration during following network boundary treatment method of the present invention illustrates, wherein User1 is that call subscriber terminal is referred to as also that first sip terminal such as number are 87541001, IP address 192.168.3.110, User2 is that also to be referred to as second sip terminal such as number be 87541002 and IP address 192.168.3.110 to called user terminal, it is on the SBC that User1 is registered in SBC1, and it is on the 2nd SBC that User2 is registered in SBC2.Calling terminal is communicated by letter with terminal called with sip server with SBC2 by the SBC1 of fire compartment wall or NAT and registration separately, as has also represented the IP address of fire compartment wall NAT, SBC1, SBC2 and sip server alive shown in scheming to go up.
User's sip terminal is regularly registered to SBC among the present invention, for example calling terminal is registered on the SBC and terminal called is registered on the 2nd SBC, the SBC server receives and preserves the SIP port mapping relation of terminal behind the registration message of terminal and act on behalf of it and carry out user's registration to sip server, periodic registration make the signaling port of terminal in the mapped port on the public network constant and before off-line continuously effective.
The processing procedure of network boundary treatment method of the present invention as shown in Figure 6, comprise step 100, the sip terminal of user 1User1 and user 2User2 is set up signalling path, wherein sets up the flow chart of signalling path process as shown in Figure 7, and step 100 is set up the signalling path process and specifically comprised the steps:
Step 180 according to expired (Expire) time of the configuration modification sip terminal registration message of SBC, and is transmitted the sip terminal of 200OK to the user, succeeds in registration.After succeeding in registration, user's sip terminal still needs the session margin control timed sending log-on message to its registration, to keep the validity of signalling path.Wherein, user terminal can be first sip terminal of user 1User1 or second sip terminal of user 2User2, and SBC can be a SBC (SBC1) or the 2nd SBC (SBC2) of first sip terminal or the registration of the second sip terminal desire.
User's sip terminal means that the foundation of signalling path is finished after finishing registration on the SBC separately.Then carry out the foundation of media channel as shown in Figure 6:
Wherein set up the flow chart of media channel process as shown in Figure 8, step 200 is set up the media channel process and is specifically comprised the steps:
Step 240 after the 2nd NAT (NAT2) receives the INVITE call request, changes purpose IP address and port the SIP private network port of terminal called User2 into, and source IP address and port are constant, and the INVITE call request message is transmitted to User2;
Step 260 after first sip terminal is received 200OK message, is replied acknowledge message (ACK) by the first session margin control and the second session margin control and is given second sip terminal;
Describe the detailed process that SBC1 handles described call request message in the step 220 below in detail:
As shown in Figure 9, for step S220 carry out before call request (INVITE) message sent of first sip terminal of the User1 that receives of SBC1, as shown in figure 10, be transmitted to the INVITE of sip server after handling through SBC1 after carrying out for step S220.The step S220 first session margin control flow chart that described call request message is handled specifically comprises the steps: as shown in figure 11
Step 221, SBC1 session control module be by adopting the Information hiding strategy of which kind of mode with the mutual decision of information hiding module, and the corresponding caller network information (calling number, Access Network IP address, network route etc.) is shielded; The strategy of Information hiding generally is to be configured by NMC in advance, can be not described in detail at this referring to some existing strategies;
Step 222, SBC1 is that the transmission of Media Stream distributes two local udp ports, and will distribute the information of local udp port to be added in the sip message body of described call request message;
Step 223, because terminal User1 is used as sip server to SBC1, so the destination of the Invite message that it sends is SBC1, but SBC1 will give real sip server this forwards, so need make amendment to this stature, SBC1 changes the Request-URI in the INVITE address of the sip server that SBC1 disposes into, and the Request-URI of the Invite message that SBC1 receives is:
INVITE?sip:87541002@10.0.0.5SIP/2.0！
After the modification be:
INVITE?sip:87541002@10.0.0.7:6060SIP/2.0！
Step 224, the Via head of modification INVITE.The Via head be used for record request message the route of process, every through a jumping, just in Via, add this and jump address information, relatively whether article one routing iinformation of Via field is the same with the source address of the message of receiving simultaneously, if different, just need to add the direct transmission address that " received=" illustrates actual this message of receiving; Echoing, it is opposite when answering message Via to be handled, every through a jumping, just removes this jumping address information.
In this example, when terminal User1 sends Invite message and do not know to have between it and the SBC1 NAT1 to exist, so its Via information is self address of filling in:
Via:SIP/2.0/UDP192.168.2.110:5060；branch＝z9hG4bKb6zMJG！
After message is dealt into SBC1, detect and find that this message sends from 10.0.0.2, do not conform to the 192.168.2.110 of Via head in the sip message, so adding " received=" gives instruction, before being transmitted to sip server, also need to add the address information of SBC1 self, the Via head just becomes as a result:
Via:SIP/2.0/UDP10.0.0.5:6060；branch＝1FC464ABF591705E2156DCB9D32A792A.80000000，
SIP/2.0/UDP
192.168.2.110:5060；branch＝z9hG4bKb6zMJG；rport＝1371；received＝10.0.0.2！；
Step 225, contact address (Contact) head of modification INVITE.This stature is used for filling out the contact address.For the response message one that guarantees the back is got back on the SBC1 server surely, rather than directly loopback (promptly so-called " message transparent transmission ") end to end, SBC1 must make amendment to it.Contact before revising is:
Contact:<sip:87541001@192.168.2.110:5060>！
After the modification be:
Contact:<sip:87541001@10.0.0.5:6060>！
Wherein, also can correspondingly handle the similar Contact header field of its processing procedure accordingly to route in the call request message (Route), record route (Record-Route) header field;
Step 226, the Content-Length of modification INVITE.This stature is the length that is used to refer to the sip message body.Because SBC revises the sip message body, may cause length variations, so need heavily fill out.Before the modification be:
Content-Length：217！
After the modification be:
Content-Length：207！
Step 227, the message body part (be SDP part) relevant of modification INVITE with medium.If Media Stream is transmitted through SBC1, SBC1 just need open special media channel for this Media Stream, and revises the sip message body.Here mainly revise " o=" field, " c=" field, these two fields are used to refer to the IP of transmitting-receiving, also will revise " m=" field, and it is used to refer to the port of transmitting-receiving.Before the modification be:
o＝-256?256IN?IP4?192.168.2.110！
c＝IN?IP4?192.168.2.110！
m＝audio?6000RTP/AVP18408101！
After the modification be:
o＝-256256IN?IP4?10.0.0.5！
c＝IN?IP4?10.0.0.5！
m＝audio?8000RTP/AVP?18408101！
Referring to Figure 12, describe the detailed process that the second session margin control is handled INVITE in the step 230 in detail:
Step 231, SBC2 receives INVITE, the first session margin control is the local udp port of the transmission distribution of Media Stream in the sip message body of SBC2 preservation call request message, if judge it is that server sends, preservation sip message body is that the RTP address information in the SDP part arrives RTP forwarding address mapping table (SBC of caller, i.e. the RTP address information of SBC1);
Step 232, SBC2 is that the transmission of Media Stream distributes two local udp ports, and will distribute the information of local udp port to be added in the sip message body of described call request message;
Step 233, inquire address number correspondence table obtains the pairing NAT address information of terminal called User2;
Step 234, similar with SBC1 to the modification of INVITE, SBC2 revises the destination address Request-URI of INVITE, the Via head, the Contact head, Content-Length and message body (SDP part) part relevant with medium, Contact field in the former message is changed into IP address and the signaling side slogan of SBC2, the Request-URI field is changed into the NAT address of User2 correspondence, corresponding modify Via field and Content-Length field, revise " o=" field in the SDP part at last, " c=" field, these two fields are inserted the IP of SBC2, also to revise " m=" field, inserting SBC2 is the RTP transmitting-receiving port of allocated for media streams, is transmitted to the second sip terminal User2 after message modification is finished; , send by protocol stack after message modification is finished.
Describe the detailed process that SBC1, SBC2 handle 200OK message in the step 250 below in detail:
Step 251, after the second sip terminal User2 received call request (INVITE) message, preservation sip message body was the RTP address information (the RTP address information of SBC2) in the SDP part, replys response message 200OK, beams back along the former road that INVITE sends;
Step 252, the SBC2 server is received response message 200OK, and message is made amendment according to the following steps:
Step 253, because terminal User2 is used as sip server to SBC2, so the destination of the 200OK message that it sends is SBC2, but SBC2 will give real sip server this forwards, so need make amendment to this stature, SBC2 changes the hyperlink request address (Request-URI) in the 200OK message into the address of the sip server that SBC2 disposes;
Step 254, contact address (Contact) head of modification 200OK message, this stature is used for filling out the contact address.For the response message one that guarantees the back is got back on the SBC2 server surely, rather than directly loopback (promptly so-called " message transparent transmission ") end to end, the IP address and the signaling side slogan that change the Contact field in the former message into SBC2 by the public network address and the port numbers of second sip terminal.
Step 255 revises the message body length (Content-Length) of 200OK message, and this stature is the length that is used to refer to the sip message body.Because SBC revises the sip message body, may cause length variations, so need heavily fill out.Revise the Via head of 200OK message.The Via head be used for record request message the route of process, every through a jumping, just in Via, add this and jump address information, relatively whether article one routing iinformation of Via field is the same with the source address of the message of receiving simultaneously, if different, just need to add the direct transmission address that " received=" illustrates actual this message of receiving; Echoing, it is opposite when answering message Via to be handled, every through a jumping, just removes this jumping address information.
Step 257, the SBC1 server is received response message 200OK, the session control module carries out once more that Information hiding is handled as IP address, the network routing iinformation of shielding 3G core net, and it is the local udp port that the transmission of Media Stream distributes that SBC1 preserves SBC2 in the sip message body of described response message; If judge that message is that server sends, preservation sip message body is the RTP address information (the RTP address information of SBC2) in the SDP part, inquire address number correspondence table obtains the pairing NAT address information of calling terminal User1, and message is carried out following modification:
Step 258, similar with SBC2 to the modification of message 200OK, SBC1 revises the destination address Request-URI of 200OK message, the Via head, the Contact head, Content-Length and message body (SDP part) part relevant with medium, Contact field in the former message is changed into IP address and the signaling side slogan of SBC1, the Request-URI field is changed into the NAT address of User1 correspondence, corresponding modify Via field and Content-Length field, revise " o=" field in the SDP part at last, " c=" field, these two fields are inserted the IP of SBC1, also to revise " m=" field, inserting SBC1 is the RTP transmitting-receiving port of allocated for media streams, is transmitted to the first sip terminal User1 after message modification is finished;
Describe the detailed process that SBC1, SBC2 handle ACK message in the step 260 below in detail:
Step 261, after the first sip terminal User1 received 200OK message, preservation sip message body was the RTP address information (the RTP address information of SBC1) in the SDP part, replys acknowledge message ACK;
Step 262, SBC1 receives ACK message, and message is carried out the next modification of step:
Step 263, because terminal User1 is used as sip server to SBC1, so the destination of the ACK message that it sends is SBC1, but SBC1 will give real sip server this forwards, so need make amendment to this stature, SBC1 changes the Request-URI in the ACK message into the address of the sip server that SBC1 disposes;
Step 264, contact address (Contact) head of modification ACK message, this stature is used for filling out the contact address.For the response message one that guarantees the back is got back on the SBC1 server surely, rather than directly loopback (promptly so-called " message transparent transmission ") end to end, the IP address and the signaling side slogan that change the Contact field in the former message into SBC1 by the public network address and the port numbers of first sip terminal.
Step 265 revises the Content-Length of ACK message, and this stature is the length that is used to refer to the sip message body.Because SBC revises the sip message body, may cause length variations, so need heavily fill out.Revise the Via head of ACK message.The Via head be used for record request message the route of process, every through a jumping, just in Via, add this and jump address information, relatively whether article one routing iinformation of Via field is the same with the source address of the message of receiving simultaneously, if different, just need to add the direct transmission address that " received=" illustrates actual this message of receiving; Echoing when answering message, it is opposite that Via is handled, and whenever jumps through one, just removes this jumping address information,, the SBC1 server after the above modification of the affirmation message ACK that receives is finished forwards it
Step 266, the SBC2 server is received acknowledge message ACK, inquire address number correspondence table obtains the pairing NAT address information of terminal called User2, and message is carried out following modification:
Step 267, similar with SBC1 to the modification of message ACK, SBC2 revises destination address Request-URI, Via head, Contact head, the Content-Length of ACK message, Contact field in the former message is changed into IP address and the signaling side slogan of SBC2, the Request-URI field is changed into the NAT address of User2 correspondence, corresponding modify Via field and Content-Length field are transmitted to the second sip terminal User2 after message modification is finished;
SBC1, SBC2 send the detailed process that quiet RTP bag is handled for the first time to first sip terminal and second sip terminal in the detailed description step 270 below:
Step 271, first sip terminal and second sip terminal send the quiet bag of RTP voice for the first time to the described local udp port of the first session margin control and the configuration of the second session margin control, and on first and second NAT, burrow, promptly, the udp port that first sip terminal of calling terminal User1 has been opened for media communication on SBC1 sends the RTP bag, burrows on NAT1; Same, the udp port that terminal called User2 has opened for media communication on the SBC2 server sends the RTP bag, burrows on NAT2;
Step 272, when SBC1 or SBC2 receive described RTP bag and RTP for the first time to transmit when not having respective items, SBC1 or SBC2 preserve described first sip terminal or second sip terminal and are mapped to RTP address information on a described NAT or the 2nd NAT, be specially: the MCC of SBC1 receives the RTP bag of terminal User1, if receive the RTP bag of sending this address (terminal User1 beats the hole of RTP bag on NAT1) for the first time, and also do not have respective items during RTP transmits, then its raw address is kept at the relevant position (the preservation terminal is mapped to the RTP address information on the NAT1) in the table; Same, the MCC of SBC2 receives the RTP bag of terminal User2, if receive the RTP bag of sending this address (terminal is beaten the hole of RTP bag on NAT2) for the first time, and also do not have respective items during RTP transmits, then its raw address is kept at the relevant position (the preservation terminal is mapped to the RTP address information on the NAT2) in the table.
Step 273, SBC2 receives the media data that SBC1 sends, be transmitted to terminal called User2 through necessary processing the (can decide whether to carry out the encoding and decoding conversion of Media Stream, the processing of encryption and decryption as required), because User2 sent out RTP in advance and wraps on the NAT2 and burrow, this Media Stream can arrive User2 by NAT2 smoothly; Same, SBC1 receives the media data that SBC2 sends, and gives calling terminal User1 through necessary processing forward, wraps on the NAT1 and burrows because User1 sends out RTP in advance, and this Media Stream can arrive User1 by NAT1 smoothly; Media channel is set up and is finished.
Set up in the process at above-mentioned steps 200 signalling paths, comprise that also the step 280 first session margin control or the second session margin control set up the exchange of media routing index, the SAG module that is SBC1 or SBC2 is notified to the MCC module with the information of relevant exchange of media, to set up corresponding exchange of media routing index.Referring to Figure 13, SBC1 and SBC2 set up the concrete grammar process of exchange of media routing index in the detailed description step 280:
With respect to traditional fire compartment wall/NAT traversing method, SBC carries out fire compartment wall/NAT and passes through biggest advantage and be not need existing network configuration is done any hypothesis and change, so SBC can adapt to any now fire compartment wall/NAT environment and can solve all fire compartment wall/NAT that might occur from now on.
The embodiment of the invention is the mechanism that example illustrates solution 3G network border issue of the present invention with the workflow of SBC in the 3G core net, but the present invention is not limited to only be applicable to the 3G core net, and it goes for other equally and comprises the various network systems based on SIP such as NGN (next generation network), multimedia enterprise communication.
Network boundary treatment method of the present invention uses the SBC server rack to be located on Access Network and the core net border, has following advantage:
1) uses SBC to carry out fire compartment wall/NAT and pass through, need not the existing network framework is done any change.
When carrying out fire compartment wall/NAT, pass through by needs, operator only need set up the SBC server between user's Intranet and VoIP server, and in the modification name server corresponding to the clauses and subclauses of call server (Call Server), get final product for the terminal of carrying out the DNS inquiry as the IP address response of call server the IP address of SBC.
2) the SBC all fire compartment wall/NAT that might occur from now on of solution that can adapt to any now fire compartment wall/NAT environment and can put things right once and for all.SBC is a kind of blanket solution.
3) because the particularity of SBC present position in network, with and can hide the characteristics of the network information, make core network safer.
It should be noted last that, above embodiment is only unrestricted in order to technical scheme of the present invention to be described, although the present invention is had been described in detail with reference to preferred embodiment, those of ordinary skill in the art is to be understood that, can make amendment or be equal to replacement technical scheme of the present invention, and not breaking away from the spirit and scope of technical solution of the present invention, it all should be encompassed in the middle of the claim scope of the present invention.
Claims (16)
1. network boundary treatment method is characterized in that comprising:
Set up signalling path between first sip terminal and second sip terminal; And
Set up media channel between described first sip terminal and second sip terminal.
2. network boundary treatment method according to claim 1 is characterized in that setting up signalling path by following steps between described first sip terminal and second sip terminal:
Described first sip terminal or second sip terminal send first log-on message to the first or second session margin control of its desire registration; The described first or second session margin control is made amendment to described first log-on message, and sends it to sip server; Sip server requires described first sip terminal or second sip terminal to authenticate; Described first sip terminal or second sip terminal send second registration message to described session margin control; And described first or second the session margin control described second registration message is handled, and second registration message is sent to sip server, authentication is by succeeding in registration.
3. network boundary treatment method according to claim 2, it is characterized in that the described first or second session margin control to described first log-on message make amendment into:
The contact address information that described session margin control is revised in first registration message is the IP address and the port of described session margin control; And the sip server address that the hyperlink request address in described first registration message is modified as the configuration of session margin control.
4. according to claim 2 or 3 described network boundary treatment methods, it is characterized in that the described first or second session margin control is treated to described second registration message:
Described session margin control is kept at the address of described first sip terminal or second sip terminal and number and the address shone upon in the address digit correspondence table on NAT, the contact address information of revising in second registration message is the IP address and the port of described session margin control; And the sip server address that the hyperlink request address in described second registration message is modified as the configuration of session margin control.
5. network boundary treatment method according to claim 4 is characterized in that setting up media channel between described first sip terminal and second sip terminal is:
First sip terminal sends call request information to the first session margin control of its registration, carries out the address change during through a NAT;
The described first session margin control is transmitted to described sip server after described call request message is handled;
The second session margin control is accepted the described call request message that described sip server sends, and after described call request message handled, sends to described second sip terminal by protocol stack;
After the described call request message that the 2nd NAT will receive is changed, be transmitted to described second sip terminal;
Described second sip terminal is replied response message to the second session margin control, the first session margin control handled and returns to by the second session margin control to it, described first sip terminal handled and return to by the first session margin control to it; And
After first sip terminal is handled acknowledge message by the first session margin control and the second session margin control, reply acknowledge message and give second sip terminal.
6. network boundary treatment method according to claim 5 is characterized in that the described first session margin control is treated to described call request message:
The first session margin control carries out network information shielding and for the transmission of Media Stream distributes local udp port, and will distribute the information of local udp port to be added in the sip message body of described call request message; And
The first words margin control is revised the hyperlink request address in the described request message related to calls, route, contact address, message body length and the message body SDP part of process.
7. network boundary treatment method according to claim 6 is characterized in that the described second session margin control is treated to described call request message:
It is the local udp port that the transmission of Media Stream distributes that the described second session margin control is preserved the first session margin control in the described call request message body, and for the transmission of Media Stream distributes local udp port, and will distribute the information of local udp port to be added in the sip message body of described call request message;
Inquire about described address digit correspondence table, obtain the NAT address information of second sip terminal; And
Revise the hyperlink request address in the described request message related to calls, route, contact address, message body length and the message body SDP part of process.
8. network boundary treatment method according to claim 7 is characterized in that also comprising: the first session margin control or the second session margin control are set up the exchange of media routing index.
9. network boundary treatment method according to claim 8 is characterized in that also comprising:
First sip terminal and second sip terminal send the quiet bag of voice for the first time to the described local udp port of the first session margin control and the configuration of the second session margin control respectively, and burrow at a NAT and the 2nd NAT; And
The first session margin control and the second session margin control carry out respective handling and transmit the quiet bag of voice after receiving the quiet bag of voice, to finish the foundation of media channel.
10. network boundary treatment method according to claim 9, after it is characterized in that the described first session margin control or the second session margin control receive the quiet bag of voice that first sip terminal and second sip terminal send for the first time, the respective handling of carrying out is: when the described first session margin control or the second session margin control are to receive the quiet bag of described voice for the first time, and when there is not respective items in the quiet packet forwarding table of voice, the described first session margin control or the second session margin control are preserved described first sip terminal or second sip terminal and are mapped to the quiet packet address information of voice on a described NAT or the 2nd NAT, then the quiet bag of voice are transmitted.
11. according to Claim 8 or 10 described network boundary treatment methods, it is characterized in that the described first session margin control or the second session margin control set up the exchange of media routing index and be:
The session control module of the described first session margin control or the second session margin control is the exchange of media information notification media session control module in the call proceeding, and indicates it to carry out the foundation of media channel;
The media session control module is protocol message H.248 with the exchange of media information translation;
Integrated business access gateway by protocol message H.248 with exchange of media information notice medium control centre;
Medium control centre sets up the exchange of media routing index by exchange of media information and is kept in the transistroute index module.
12. according to any described network boundary treatment method of claim 5-10, it is characterized in that the described second session margin control is treated to described response message: revise the hyperlink request address in the described response message, route, contact address, message body length and the message body SDP part of process.
13., it is characterized in that the described first session margin control is treated to described response message according to any described network boundary treatment method of claim 5-10:
It is that the transmission of Media Stream distributes local udp port that the described first session margin control is preserved the second session margin control in the sip message body of described response message;
Inquire about described address digit correspondence table, obtain the NAT address information of first sip terminal; And
Revise the hyperlink request address in the described response message, route, contact address, message body length and the message body SDP part of process.
14., it is characterized in that the described first session margin control is treated to described acknowledge message: to revising hyperlink request address, the route of process, contact address, the message body length in the described acknowledge message according to any described network boundary treatment method of claim 5-10.
15., it is characterized in that the described second session margin control is treated to described acknowledge message according to any described network boundary treatment method of claim 5-10:
Inquire about described address digit correspondence table, obtain the NAT address information of second sip terminal; And
Revise hyperlink request address, the route of process, contact address, message body length in the described acknowledge message.
16. network boundary treatment method according to claim 2, it is characterized in that also comprising: after succeeding in registration, first sip terminal or second sip terminal are still to the first or second session margin control timed sending log-on message of its registration, to keep the validity of signalling path.
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