Pinning the route of IP bearer flows in a next generation network
View Patent ↗Methods and systems for extending the IMS/SIP architecture of the NGN to provide QoS service to generic bearer flows. More particularly, a method is provided for establishing an bearer end-to-end path of a communication session in a multi-domain communication network in which an out of band signalling protocol is used to establish communications sessions. The method comprises receiving an out-of-band signalling message including information representative of at least an opposite end point of a first bearer segment of the end-to-end path. The information is used to define a cross-connect mapping through a node of the network between respective local endpoints of the first bearer segment and a second bearer segment hosted by the node. Information representative of the cross-connect mapping is then inserted into the out-of-band signalling message, and the out-of-band signalling message forwarded.
1. In an Internet Protocol (IP) multi-domain communication network in which an out of band signalling protocol is used to establish communications sessions, a method of establishing a bearer end-to-end path of a communication session, the method comprising steps of:
receiving an out-of-band signalling message including information representative of at least an opposite end point of a first bearer segment of the end-to-end path;
altering the information to define a cross-connect mapping through a gateway of the network between respective local endpoints of the first bearer segment and a second bearer segment hosted by the gateway, the gateway being selected to establish the bearer end-to-end path of the communication session;
inserting the altered information representative of the cross-connect mapping into the out-of-band signalling message; and
forwarding the out-of-band signalling message.
2. The method as claimed in claim 1 , further comprising, when the out-of-band message is a forward phase message of the out-of-band signalling protocol, steps of:
receiving a return phase message of the out-of-band signalling protocol from an opposite end point of the second bearer segment, the return phase message being generated by an opposite end-point of the end-to-end path in response to receipt of the out-of-band signalling message;
defining a reverse phase cross-connect mapping through the selected gateway between respective local endpoints of the second bearer segment and the first bearer segment;
forwarding the return phase message to the opposite end-point of the first bearer segment; and
establishing a bidirectional bearer end-to-end path based on the defined cross-connect mapping and the defined reverse phase cross-connect mapping through the selected gateway.
3. The method as claimed in claim 2 , wherein out of band signalling protocol is Session Initiation Protocol (SIP), and wherein:
the forward phase message is a SIP INVITE message; and
the return phase signalling message is a SIP response message generated by a far end of the end-to-end path.
4. The method as claimed in claim 1 , wherein the step of defining a cross-connect mapping comprises steps of:
identifying respective local endpoints of the first and second bearer segments; and
defining a mapping through the selected gateway between the identified local end-points.
5. The method as claimed in claim 1 , wherein the step of inserting information representative of the cross-connect mapping into the out-of-band-signalling message comprises a step of inserting information identifying the local endpoint of the second bearer segment.
6. The method as claimed in claim 5 , wherein the information identifying the local endpoint of the second bearer segment replaces the information identifying the opposite end-point of the first bearer segment.
7. The method as claimed in claim 1 , wherein the out-of-band signalling message is a SIP-INVITE message received at a Call State Control Function (CSCF) network element controlling the selected gateway, and wherein the step of defining a cross-connect mapping comprises steps of inserting into at least one control message information representative of the cross-connect mapping; transmitting the at least one control message to the selected gateway; and installing the cross-connect mapping as a forwarding policy of that selected gateway.
8. The method as claimed in claim 7 , wherein, the step of forwarding the out-of-band message comprises a step of forwarding the SIP-INVITE message to a peer CSCF.
9. The method as claimed in claim 1 , wherein the selected gateway is any one of: a border gateway between domains of the network; and a server within a domain of the network.
10. The method as claimed in claim 1 , wherein the information is encoded in Session Description Protocol (SDP).
11. The method as claimed in claim 1 , wherein the information comprises an IP flow specification including a respective IP address of at least one end-point of the bearer segment.
12. The method as claimed in claim 1 , wherein the step of altering the information to define a cross-connect mapping comprises a step of defining a Network Address Translation (NAT) mapping for translating a header of IP packets received by the selected gateway through the first bearer segment into a header for the second bearer segment.
13. The method as claimed in claim 1 , wherein the step of altering the information to define a reverse phase cross-connect mapping comprises a step of defining a corresponding reverse phase Network Address Translation (NAT) mapping for translating a header of IP packets received by the selected gateway through the second bearer segment into a header for the first bearer segment.
14. In an Internet Protocol (IP) multi-domain communication network in which an out of band signalling protocol is used to establish communications sessions, a Call State Control Function (CSCF) network element to establish a bearer end-to-end path of a communication session, the CSCF network element being operative to:
receive an out-of-band signalling message including information representative of at least an opposite end point of a first bearer segment of the end-to-end path;
alter the information to define a cross-connect mapping through a gateway of the network between respective local endpoints of the first bearer segment and a second bearer segment hosted by the gateway, the gateway being selected to establish the bearer end-to-end path of the communication session;
insert the altered information representative of the cross-connect mapping into the out-of-band signalling message; and
forward the out-of-band signalling message.
15. The network element as claimed in claim 14 , wherein, when the out-of-band message is a forward phase message of the out-of band signalling protocol, the network element further being operative to:
receive a return phase message of the out-of-band signalling protocol from an opposite end point of the second bearer segment, the return phase message being generated by an opposite end-point of the end-to-end path in response to receipt of the out-of band signalling message;
define a reverse phase cross-connect mapping through the selected gateway between respective local endpoints of the second bearer segment and the first bearer segment;
forward the return phase message to the opposite end-point of the first bearer segment; and
establish a bidirectional bearer end-to-end path based on the defined cross-connect mapping and the defined reverse phase cross-connect mapping through the selected gateway.
16. The network element as claimed in claim 15 , wherein out of band signalling protocol is Session Initiation Protocol (SIP), and wherein:
the forward phase message is a SIP INVITE message; and
the return phase signalling message is a SIP response message generated by a far end of the end-to-end path.
17. The network element as claimed in claim 14 , wherein the network element is further being operative to:
identify respective local endpoints of the first and second bearer segments; and
define a mapping through the selected gateway between the identified local end-points.
18. The network element as claimed in claim 14 , wherein the network element inserts information representative of the cross-connect mapping into the out-of band-signalling message, the inserted information identifying the local endpoint of the second bearer segment.
19. The network element as claimed in claim 18 , wherein the information identifying the local endpoint of the second bearer segment replaces the information identifying the opposite end-point of the first bearer segment.
20. The network element as claimed in claim 14 , wherein the out-of-band signalling message is a SIP-INVITE message received at a Call State Control Function (CSCF) network element controlling the selected gateway, and wherein while defining a cross-connect mapping the network element is being operative to insert into at least one control message information representative of the cross-connect mapping; transmit the at least one control message to the selected gateway; and install the cross-connect mapping as a forwarding policy of that selected gateway.
21. The network element as claimed in claim 20 , wherein the step of forwarding the out-of-band message comprises a step of forwarding the SIP-INVITE message to a peer CSCF network element.
22. The network element as claimed in claim 14 , wherein the selected gateway is any one of: a border gateway between IP domains of the network; and a server within an IP domain of the network.
23. The network element as claimed in claim 14 , wherein the information is encoded in Session Description Protocol (SDP).
24. The network element as claimed in claim 14 , wherein the information comprises an IP flow specification including a respective IP address of at least one end-point of the bearer segment.
25. The network element as claimed in claim 14 , wherein network element defines a Network Address Translation (NAT) mapping for translating a header of IP packets received by the selected gateway through the first bearer segment into a header for the second bearer segment.
26. The network element as claimed in claim 25 , wherein the network element defines a corresponding reverse phase Network Address Translation (NAT) mapping for translating a header of IP packets received by the selected gateway through the second bearer segment into a header for the first bearer segment.