System for switching from an established media path to a new media path in a packet based network
There is described a system for switching from an established media path to a new media path for packets transmitted between first and second end points in a packet based network. An instruction is transmitted to the first end point instructing it to set up a new receiving channel for receiving packets transmitted from the second end point over the new media path. An instruction is transmitted to the second end point instructing it to configure a sending channel to send packets over the new media path for reception on the new receiving channel of the first end point. For a time period during the switching, the first end point monitors for packets simultaneously on both its new receiving channel and an established receiving channel configured to receive packets transmitted from the second end point over the established media path. This systems helps ensure a seamless switchover from the established to the new media paths.
1. A method for switching from an established media path to a new media path for packets transmitted between first and second end points in a packet based network, the method comprising:
transmitting, by a network element, an instruction to the second end point instructing it to set up a new receiving channel for receiving packets transmitted from the first end point over the new media path;
transmitting, by the network element, an instruction to the first end point instructing it to configure a sending channel to send packets over the new media path for reception on the new receiving channel of the second end point;
wherein the first endpoint, after being informed by the network element that the new receiving channel is setup, reconfigures the sending channel to begin sending packets over the new media path for reception on the new receiving channel of the second end point to remove the network element from a media path between the first and second end points; and
wherein for a time period, the second end point monitors for packets simultaneously on both its new receiving channel and an established receiving channel configured to receive packets transmitted from the first end point over the established media path.
2. A method according to claim 1 , further comprising:
transmitting an instruction to the first end point instructing it to set up a new receiving channel for receiving packets transmitted from the second end point over the new media path;
transmitting an instruction to the second end point instructing it to configure sending channel to send packets over the new media path for reception on the new receiving channel of the first end point; and wherein
for a time period during the switching, the first end point monitors for packets simultaneously on both its new receiving channel and an established receiving channel configured to receive packets transmitted from the second end point over the established media path.
3. A method according to claim 2 wherein either of the first and second end point is able to synchronize media packets received via its established receiving channel and media packets received via its new receiving channel into one stream.
4. A method according to claim 3 wherein packet counters are used to allow end point reordering of media packets.
5. A method according to claim 3 wherein an occurrence of a Silence Insertion Descriptor (SID) frame is used as a synchronisation point by either of the first and second end points for switching from the established media path to the new media path.
6. A method according to claim 3 wherein sender reports (SR) of the Real Time Protocol Control Protocol (RTCP) which contain statistics such as timestamps and packet sequence numbers and source description (SDES) are used by either of the first and second end points for synchronising switching from the established media path to the new media path.
7. A method according to claim 3 wherein proprietary enhancements of RTP/RTCP are used by either of the first and second end points for synchronising switching from the established media path to the new media path.
8. A method according to claim 1 , wherein, at least one of the first and second end points is a VoIP end point.
9. A method according to claim 1 , wherein the end point supports RTP/RTCP and SIP or H.323.
10. A method according to claim 1 , wherein the network element is a private branch exchange (PBX).
11. Apparatus for switching from an established media path to a new media path for packets transmitted between first and second end points in a packet based network, the apparatus comprising:
means for transmitting, by a network element, an instruction to the second end point instructing it to set up a new receiving channel for receiving packets transmitted from the first end point over the new media path;
means for transmitting, by the network element, an instruction to the first end point instructing it to configure a sending channel to send packets over the new media path for reception on the new receiving channel of the second end point;
wherein the first endpoint, after being informed by the network element that the new receiving channel is setup, reconfigures the sending channel to begin sending packets over the new media path for reception on the new receiving channel of the second end point to remove the network element from a media path between the first and second end points; and
wherein for a time period, the second end point monitors for packets simultaneously on both its new receiving channel and an established receiving channel configured to receive packets transmitted from the first end point over the established media path.
12. An apparatus according to claim 10 , wherein the network element is a private branch exchange (PBX).
13. A method for switching from an established media path to a new media path for packets transmitted between first and second end points in a packet based network, the method comprising:
transmitting, by a network element, an instruction to the second end point instructing it to set up a new receiving channel for receiving packets, via a second wireless access point, transmitted from the first end point over the new media path;
transmitting, by the network element, an instruction to the first end point instructing it to configure a sending channel to send packets over the new media path for reception on the new receiving channel of the second end point;
wherein for a time period, the second end point monitors for packets simultaneously on both its new receiving channel and an established receiving channel configured to receive packets, via a first wireless access point, transmitted from the first end point over the established media path; and
wherein the first endpoint, after being informed by the network element that the new receiving channel is setup, reconfigures the sending channel to begin sending packets over the new media path for reception on the new receiving channel of the second end point to remove the first wireless access point from a media path between the first and second end points.
14. A method according to claim 13 , wherein the network element is a wireless local area network (WLAN) controller.