Patent Application
20090279450
Modern packet-oriented networks, also referred to as “data networks”, have until now been designed essentially for the transmission of packet streams, which are also referred to in the specialist world as “data packet streams”. In this case, there is normally no need for any guaranteed transmission Quality of Service. The data packet streams are thus transmitted, for example, with fluctuating time delays since the individual data packets in the data packet streams are normally transmitted in the sequence of their network access; that is to say, the time delays become greater the greater the number of packets to be transmitted by a data network. In the specialist world, transmission of data is, therefore, also referred to as a transmission service without any realtime conditions, or as a “non-realtime service”.
In the course of convergence of line-oriented voice and packet-oriented data networks, realtime services, that is to say transmission services subject to the realtime conditions such as the transmission of voice or moving picture information, are likewise increasingly being provided in packet-oriented networks. That is the previously normal realtime services which were transmitted on a line-oriented basis are transmitted in a packet-oriented manner, or in packet streams, in a convergent voice/data network. These are also referred to as “realtime packet streams”. This results in the problem that a high Quality of Service is required for packet-oriented transmission of a realtime service whose quality is comparable to that when using line-oriented transmission. In particular, a minimal, for example <200 ms, delay without any fluctuations in the delay time is important, since realtime services generally require a continuous information flow and any loss of information, such as that resulting from packet losses, cannot be compensated for by transmitting the rejected packets once again. Since, in principle, these Quality of Service requirements apply to all networks using packet-oriented transmission, they are independent of the specific configuration of a packet-oriented network. The packets may, in consequence, be in the form of Internet, x.25 or frame-relay packets, or in the form of ATM cells.
In order to transmit voice and picture information via the packet-oriented Internet, also referred to as “VoIP”—the International Standards (in particular, the H.323 Standard) contain proposed protocols for transmission through the Internet. In this case, the network is broken down into a number of “H.323 zones”, in each of which “gatekeepers” are provided for
Since, however, the present H.323 Standards do not include any guaranteed Qualities of Service for Internet transmission, the present VoIP technology has the disadvantage that the quality of voice and picture transmission decreases as the number of packets to be transmitted by the Internet rises. In this context, K. Nichols, “Differentiated Services Operational Model and Definitions”, IETF Draft, 1998 proposes that a number of service classes be introduced in the packet-oriented Internet, which previously did not guarantee any Qualities of Service. In this case, the individual packet streams are each allocated to a specific service class and are transmitted with high priority or low priority in comparison to packets in other service classes, depending on their service class, by the transmission nodes in the Internet. The Quality of Service required for realtime services can, thus, be guaranteed, for example, by allocating the associated realtime packet streams to a service class which is transmitted with high priority by the nodes in the Internet—the realtime packet streams are thus prioritized over the data packet streams.
In principle, network access monitoring is required at least for the prioritized traffic for priority-controlled transmission since the required Quality of Service can be guaranteed only when the number of prioritized packets supplied to the network is not greater than the maximum number which can be transmitted by the network. To this end, network gateway devices—also referred to as “edge devices”—have been proposed for the Internet with a number of service classes, and these devices provide the network access monitoring. In this case, the edge devices can
Until now, there has been no control over the allocation of the Quality of Service; that is, there is a problem as to how Qualities of Service for the packet streams are requested, allocated and signaled to the edge devices before being transmitted. A method is known, in which a reservation protocol RSVP is used by each transmission node in a communications network, to request a Quality of Service required for the transmission of a packet stream, and in which the packet stream is not transmitted if at least one transmission node cannot provide the requested Quality of Service. In this case, the reservation protocol RSVP must be provided in each of the transmission nodes.
The present invention is thus directed toward designing a method for allocation of a Quality of Service for the transmission of a packet stream via a packet-oriented communications network with service classes.
A major aspect of the present invention is the allocation of a Quality of Service for a service in which the service is provided in at least one communications network which transmits packets and/or packet streams in a packet-oriented manner as a function of Qualities of Service, use of the service is requested with a controller, and the controller allocates the Quality of Service for the requested use of the service as a function of the service and/or of the requested use of the service. A major advantage of the present invention is that the use of the service is requested rather than the allocation of a Quality of Service. The controller can thus allocate different Qualities of Service to the requested service, for example with a high Quality of Service if the transmission capacity in the communications network is sufficient, and with a low Quality of Service if the transmission capacity in the communications network is insufficient. Furthermore, the Quality of Service is advantageously allocated on a packet-stream-specific basis. This is a particular advantage if transmission with a guaranteed packet-stream-specific Quality of Service is not provided in the communications network.
According to an embodiment of the method according to the present invention, the use of the service is requested without stating the Quality of Service. There is, thus, no need to determine the Quality of Service when requesting use of the service.
According to another embodiment of the method according to the present invention, the service is in the form of transmission of information; in particular, voice information. In a further embodiment of the method, when the service is being used by the communications network, at least one packet stream which is allocated to the service is transmitted with the Quality of Service. The invention can, thus, preferably be used to satisfy particular Quality of Service requirements for the transmission of voice information via a packet-oriented communications network; in particular, an integrated voice/data network.
According to another embodiment of the present invention, the controller checks whether the requested use of the service can be provided with the intended Quality of Service by the communications network. The check is then carried out by the controller and not by the communications network, thus relieving the load on the communications network.
According to an embodiment of the method according to the present invention, the controller signals the Quality of Service of the packet stream to a network gateway device, before the network gateway device transmits the packet stream with its Quality of Service to the packet-oriented communications network. This advantageously leads to the packet stream being transmitted by the network gateway device with the allocated Quality of Service to the communications network.
According to another embodiment of the method according to the present invention, at least one acknowledgement of the signaled Quality of Service is required for the permissibility of the packet stream. This ensures that the packet stream is permissible only if the allocated Quality of Service can be transmitted. The signaling and subsequent acknowledgement of the Quality of Service can, thus, be integrated in the permissibility check, by which the permissibility check and the allocation of the Quality of Service can be carried out as a unit, that is to say consistently.
According to another embodiment of the method according to the present invention, the Quality of Service is signaled with the aid of signaling packets. The signal then can be transmitted in the same way that the packet stream is transmitted.
According to a further embodiment of the method according to the present invention, at least one high Quality of Service and one low Quality of Service are provided in the communications network. In this case, the present invention provides for the packet streams with a high Quality of Service to be transmitted with priority by the network gateway device. Packet streams which are intended for transmitting information in realtime, that is to say with delay times that are as short as possible, can thus be transmitted with priority over packet streams which can transmit information with variable delay times. Examples of information which are transmitted with a high Quality of Service are voice or video telephony. Examples of information which are transmitted with a low Quality of Service are E-mail, files or Internet pages.
According to another embodiment of the method according to the present invention, a Quality of Service tag is provided in the packets in the data streams. In this case, the network gateway device transmits those packet streams which are to be transmitted by it with a high Quality of Service with a first Quality of Service tag which represents the high Quality of Service, and transmits the remaining packet streams with a second Quality of Service tag, which represents the low Quality of Service. Transmitting the allocated Quality of Service in the packets in the data stream thus makes it possible, by reading the Quality of Service tag in the transmission node in the communications network, to determine the allocated Quality of Service while the packet stream is being transmitted, thus making it unnecessary to store the allocated Quality of Service in the transmission nodes.
According to an embodiment of the method according to the present invention, the Quality of Service is produced on the basis of priorities, with the high Quality of Service being stated as the high priority and the low Quality of Service being stated as the low priority, and the Quality of Service tag has been stated as the priority tag. The prioritized transmission of the packet streams with a high Quality of Service can thus be achieved in a simple manner via known mechanisms for priority control.
According to yet another embodiment of the method according to the present invention, the network gateway device is in the form of an edge device, the packets are in the form of Internet packets, and the controller is in the form of a gatekeeper in accordance with International Standard H.323. The method according to the present invention then can advantageously be introduced into the existing infrastructure of a modern Internet. Furthermore, the Quality of Service can be allocated as a function of the permissibility check by the gatekeeper.
Additional features and advantages of the present invention are described in, and will be apparent from, the following Detailed Description of the Invention and the Figures.
By way of example,
By way of example,
For the exemplary embodiment, it is assumed that a number of Qualities of Service DG are provided, at least in the Internet IN, and are indicated to the Internet via the Quality of Service tag DK provided in the Internet packets IP. Furthermore, data D is already being transmitted by the computer C (1) to the computer C (2) via the packet stream ST3 with the low Quality of Service ND. It is now also intended to transmit voice information V between the two end points EP, for example the telephones T (1), T (2), and this is intended to be done at least via the Internet IN using a high Quality of Service HD. To this end, once a telephone number which is structured in accordance with the International Standard E.164 has been entered, the telephone T (1) requests a connection to the telephone T (2). This is also referred to as call admission CA. During the first call admission CA (1), the telephone T (1) makes a request in the LAN L1 to transmit the packet stream ST1 to the telephone T (2), by the telephone T (1) sending a first admission request message ARQ (1) to the gatekeeper GA (1). The gatekeeper GK (1) then translates at least the telephone number to the Internet address of the telephone T (2). According to the present invention, the gatekeeper GK (1) also assigns the high Quality of Service HD to the packet stream ST1 and signals this to the network gateway device NE (ED (1)) via the signal M (11). For example, a transmission capacity of 64 kbps could be requested. The gatekeeper GK (1) then transmits a first admission confirmation message ACF (1) to the telephone T (1), and this can, optionally, be done as a function of the acknowledgement B (11) sent back as the response from the network gateway device NE (ED (1)) to the gatekeeper GK (1). The telephone T (1) then initiates the process of setting up a connection to the telephone T (2) by sending to the telephone T (2) a call set-up message CS in accordance with the internationally standardized monitoring protocol H.225. In this case, inter alia, the protocol and port number of the telephone T (1) are also signaled to the gatekeeper GK (1), and are signaled by the gatekeeper GK (1) to the network gateway device NE (ED (1)) using the signal M (12).
Since, owing to the bidirectional character of a voice connection, two voice packet streams STV—the packet stream ST1 for transmission of the voice information V from the telephone T (1) to the telephone T (2), and the packet stream ST2 for transmitting the voice information V from the telephone T (2) to the telephone T (1)—are required, the telephone T (2) requests the packet stream ST2, once the call set-up message CS has been received. The packet stream ST2 is set up analogously to the setting up of the packet stream ST1. Following this, the telephone T (2) makes a second call admission CA (2), with the gatekeeper GK (2) signaling, once a second admission request message ARQ (2) has been received, the requested high Quality of Service HD to the network gateway device NE (ED (2)) via the signal M (21) according to the present invention. This could be acknowledged in an analogous manner using the acknowledgement B (21). The call admission CA is terminated by a second admission confirmation message ACF (2), following which the second telephone T (2) sends a connect message CO to the first telephone T (1). In order to complete the setting up of the connection, the protocol number and the port number of the telephone T (2) are signaled to the network gateway device NE (ED (2)) using the signal M (22). The voice information V is now transmitted with a high Quality of Service via the packet streams ST1, ST2 between the two telephones T (1), T (2); that is, the transmission takes place with priority over the transmission of the packet stream ST3 which is to be transmitted with the low Quality of Service ND.
After completion of the call, the telephone T (1), for example, initiates the clearing of the connection, also referred to as “End Session”, by sending to the telephone T (2) a first call teardown message CT (1) in accordance with International Standard H.245. Once this message has been received, at the earliest, the gatekeeper GK (1) can signal the clearing of the connection to the network gateway device NE (ED (1)) via the signal M (13) following which the reserved high Quality of Service HD could be enabled by the network gateway device NE (ED (1)). Once the first call teardown message CT (1) has been received, the telephone T (2) likewise sends a second call teardown message CT (2), in response to which the gatekeeper GK (2) could also send the signal M (23) to the network gateway device NE (ED (2)). The signals M (13), M (23) contain, for example, the Internet addresses and port numbers of the two telephones T (1) and T (2), protocol numbers and/or the transmission capacities required by the voice packet streams STV. After receiving the call teardown message CT (2), the telephone T (1) sends a release complete message RC, and then initiates a first call disengage CD (1), by transmitting a first disengage request message DRQ (1) to the gatekeeper GK (1). The gatekeeper GK (1) then uses the signal M (14) to signal to the network gateway device NE (ED (1)) the end of the transmission of the packet stream ST1, and the call disengage CD (1) is completed by sending a first disengage confirm message DCF (1). After receiving the release complete message RC, the telephone T (2) initiates a second call disengage CD (2) in an analogous manner by transmitting a second disengage request message DRQ (2) to the gatekeeper GK (2). The gatekeeper GK (2) then uses the signal M (24) to signal to the network gateway device NE (ED (2)) the end of the transmission of the packet stream ST2, and the call disengage CD (2) is completed by sending a second disengage confirm message DCF (2).
According to one variant of the present invention, the signaling packets MP (2) are used to signal the high Quality of Service HD of the packet stream ST1 to the network gateway device NE (ED (2)). The network gateway device NE (ED (2)) can then transmit the packet stream ST1 with priority; that is, both within the network gateway device NE (ED (2)) itself and, provided this is technically feasible in the LAN L2, by priority transmission to the LAN L2 and/or in the LAN L2.
According to a further variant of the present invention, the Qualities of Service DG are signaled to the network gateway devices NE (ED (1)), NE (ED (2)) and to the gatekeeper GK using a reservation protocol; for example, the reservation protocol RSVP.
Finally, it should be mentioned that the present invention is not restricted to an Internet IN, but can be used in any packet-oriented communications network KN with Qualities of Service DG. For example, use in local area networks L1, L2 is envisioned. This is indicated in
Indeed, although the present invention has been described with reference to specific embodiments, those of skill in the art will recognize that changes may be made thereto without departing from the spirit and scope of the invention as set forth in the hereafter appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 199 10 585.5 | Mar 1999 | DE | national |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 09936488 | Dec 2001 | US |
| Child | 12267335 | US |
