Congestion control for tunneled real-time communications

A system performs congestion control functionality for real-time communications (“RTC”). The system establishes a tunnel by a tunneling server with a tunneling client of a user equipment (“UE”). The system receives a request from the UE to enable the congestion control functionality for an inner socket of the tunnel. The system sends a response back to the UE to indicate that the congestion control functionality is enabled for the inner socket. The system then monitors congestion conditions at an outer transport layer of the tunnel and executes the congestion control functionality at an inner transport layer of the tunnel based on the congestion conditions at the outer transport layer of the tunnel.

FIELD

One embodiment is directed generally to a communications network, and in particular, to delivering real-time traffic over a communications network.

BACKGROUND INFORMATION

Many enterprise environments have replaced their Public Switched Telephone Network (“PSTN”) telephony services with telephony services that use the Internet Protocol (“IP”), commonly known as Voice over IP (“VoIP”) or IP Telephony. Since IP Telephony uses an IP network as its backbone, it can provide advanced features such as video conferencing, call recording, and call forwarding.

Recently, the growing base of mobile data subscribers, the wide availability of Internet access, and the high availability of bandwidth in both fixed and mobile networks has resulted in the popularity of advanced services accessed via the Internet (known as Over-the-Top (“OTT”) services). This has caused competitive service providers to offer OTT services and hence face corresponding challenges as they implement these new services.

SUMMARY

One embodiment is a system that performs congestion control functionality for real-time communications (“RTC”). The system establishes a tunnel by a tunneling server with a tunneling client of a user equipment (“UE”). The system receives a request from the UE to enable the congestion control functionality for an inner socket of the tunnel. The system sends a response back to the UE to indicate that the congestion control functionality is enabled for the inner socket. The system then monitors congestion conditions at an outer transport layer of the tunnel and executes the congestion control functionality at an inner transport layer of the tunnel based on the congestion conditions at the outer transport layer of the tunnel.

DETAILED DESCRIPTION

One embodiment provides congestion control services for real-time communications (“RTC”) in a tunneling environment. In one embodiment, based on congestion information at the outer layer of a tunnel, a tunneling client throttles RTC traffic at the inner layer of the tunnel, causing the throughput of encapsulated media being temporarily and intentionally reduced in order to accelerate recovery from congestion and improve the overall RTC quality. Accordingly, in case of congestion, embodiments provide RTC that is only affected by short periods of media choppiness, thus preventing long periods of dead air and/or dropped speech/video phone calls.

FIG. 1is an overview diagram of a network100including network elements that implement embodiments of the present invention and/or interact with embodiments of the present invention. Network100includes a user equipment (“UE”)102that performs RTC over an Internet Protocol (“IP”) network114with a service provider network122. In RTC, users exchange information instantly or with insignificant latency. Example applications for RTC include voice and/or video calls, application streaming, softphones, and remote desktop applications. UE102may be any device used by an end-user for communications, such as a smartphone, a laptop computer, a tablet, a television, etc.

In performing RTC, UE102communicates signaling and media traffic with respective servers124in service provider network122. Signaling traffic may be communicated according to an application layer protocol such as the Session Initiation Protocol (“SIP”). SIP is configured to be independent of the underlying transport layer. Accordingly, SIP can run on different transport protocols, such as the Transmission Control Protocol (“TCP” as described in, for example, Internet Engineering Task Force (“IETF”) request for comments (“RFC”) 793 and RFC 675), the User Datagram Protocol (“UDP” as described in, for example, IETF RFC 768), etc.

Network100further includes a tunneling server116that, together with a tunneling client106within UE102, provides functionality for establishing and managing tunnels for performing RTC according to the Tunneled Services Control Function (“TSCF”) standard as described in, for example, 3rd generation partnership program (“3GPP”) technical report (“TR”) 33.830 V0.5.0, the disclosure of which is hereby incorporated by reference in its entirety. In one embodiment, tunneling client106and tunneling server116establish a TSCF tunnel108that is compliant with TSCF tunnel management (e.g., tunnel initialization, maintenance, termination, etc., as defined by, e.g., 3GPP TR 33.830 V0.5.0), and TSCF tunnel transport protocols are supported for the negotiation of TSCF tunnel108between tunneling client106and tunneling server116.

The TSCF standard provides client side and server side network elements for establishing managed tunnels for performing RTC (e.g., tunneling client106and tunneling server116inFIG. 1). It also provides two types of outer layer tunneling transports: a stream-based outer layer tunneling transport via TCP or Transport Layer Security (“TLS”), and a datagram-based outer layer tunneling transport via UDP or Datagram Transport Layer Security (“DTLS”).

TLS is a cryptographic protocol as provided in, for example, IETF RFC 2246, RFC 4346, RFC 5246, and/or RFC 6176. DTLS is a protocol that provides communications privacy for datagram protocols. TCP and TLS provide reliable, ordered and error-checked delivery of the inner layer traffic, but introduce undesirable latency that is detrimental to RTC applications over a communications network that experiences impairments. On the other hand, UDP and DTLS do not guarantee reliable delivery, thus minimizing latency and being desirable for RTC.

In some embodiments, IP network114may include security devices (e.g., firewalls, proxies, etc.) that allow traffic of only a certain transport protocol (e.g., only TCP, only UDP, etc.). Accordingly, tunneling client106and tunneling server116may establish and manage TSCF tunnel108such that UE102may use it to traverse such security devices and connect to tunneling server116to reach servers124in service provider network122.

The TSCF standard further provides control messages for exchanging configuration information between tunneling client106and tunneling server116. According to the TSCF standard, control messages are of a “request/response” type, and a control message response for a request includes either a corresponding reply or an error code indicating why the request cannot be honored by the receiving end. TSCF control messages use a Type Length Value (“TLV”) encoding. TLV is a variable length concatenation of a unique type and a corresponding value.

Each TSCF control message includes a control message header at the beginning, including a “CM_Version” field identifying the version of the header and indicating the outer transport protocol of a TSCF tunnel, a “CM_Indication” field identifying whether the message is a control message or not, a “Reserved” field reserved for future use, a “CM_Type” field identifying the type of the control message (e.g., whether it is a request or a response, the corresponding functionality, etc.), a “TLV_Count” field indicating the number of TLVs that follow or are appended to the header in the corresponding control message, a “Tunnel Session ID” (“TSID”) field including a tunnel session identifier (“ID”) assigned by tunneling server116to uniquely identify TSCF tunnel108, and a “Sequence” field that is incremented per message, as described in, for example, 3GPP TR 33.830 V0.5.0.

In one embodiment, in order to establish TSCF tunnel108, tunneling client106sends a “configuration request” message to tunneling server116to obtain configuration information for TSCF tunnel108. In a “configuration request” message, the TSID header field bits are set to 1 (i.e., FFFF . . . ). In response, tunneling server116assigns a TSID to a TSCF tunnel and sends a “configuration response” message back to tunneling client106. The “configuration response” message includes the TSID assigned by tunneling server116to TSCF tunnel108. The subsequent messages between tunneling client106and tunneling server116include this assigned TSID in their headers.

In one embodiment, if a control message is communicated between tunneling client106and tunneling server116and does not include the expected TSID, the control message is dropped and the corresponding TSCF tunnel is terminated. Alternatively, in one embodiment, tunneling client106may send a “configuration release request” message to tunneling server116to terminate a TSCF tunnel. In response to such a “configuration release request” message, tunneling server116sends a “configuration release response” message to tunneling client106. At this time, TSCF tunnel108is terminated.

In one embodiment, UE102executes an application104that may be a SIP based RTC application relying on a library such as the software development kit (“SDK”) provided by the tunneled session management solution from Oracle Corp.

FIG. 2is a block diagram of a computer server/system (i.e., system10) in accordance with an embodiment of the present invention. System10can be used to implement any of the network elements shown inFIG. 1as necessary in order to implement any of the functionality of embodiments of the invention disclosed in detail below. Although shown as a single system, the functionality of system10can be implemented as a distributed system. Further, the functionality disclosed herein can be implemented on separate servers or devices that may be coupled together over a network. Further, one or more components of system10may not be included. For example, for the functionality of tunneling server116ofFIG. 1, system10may be a server that in general has no need for a display24or one or more other components shown inFIG. 2.

System10includes a bus12or other communication mechanism for communicating information, and a processor22coupled to bus12for processing information. Processor22may be any type of general or specific purpose processor. System10further includes a memory14for storing information and instructions to be executed by processor22. Memory14can be comprised of any combination of random access memory (“RAM”), read only memory (“ROM”), static storage such as a magnetic or optical disk, or any other type of computer readable medium. System10further includes a communication device20, such as a network interface card, to provide access to a network. Therefore, a user may interface with system10directly, or remotely through a network, or any other method.

Processor22may further be coupled via bus12to a display24, such as a Liquid Crystal Display (“LCD”). A keyboard26and a cursor control device28, such as a computer mouse, may further be coupled to bus12to enable a user to interface with system10on an as needed basis.

In one embodiment, memory14stores software modules that provide functionality when executed by processor22. The modules include an operating system15that provides operating system functionality for system10. The modules further include a congestion control module16for providing congestion control, and all other functionality disclosed herein. In one example embodiment, congestion control module16may implement tunneling server116ofFIG. 1in conjunction with one or more remaining elements ofFIG. 2. System10can be part of a larger system, such as added functionality to the “Acme Packet 4500” session border controller from Oracle Corp. Therefore, system10can include one or more additional functional modules18to include the additional functionality. A database17is coupled to bus12to provide centralized storage for congestion control module16and additional functional modules18.

In one embodiment, congestion control module16and/or additional functional modules18may include several modules to provide congestion control functionality, as will be described herein with reference toFIG. 5. The modules in one embodiment include a tunneling module that establishes a tunnel with a tunneling client of a user equipment and a monitoring module that monitors congestion conditions at an outer transport layer of the tunnel and executes the congestion control functionality at an inner transport layer of the tunnel.

Referring again toFIG. 1, with known systems, TSCF tunnel108may encapsulate different types of traffic ranging from pure data to real-time media. In general, data and real-time media are subject to different Quality of Service (“QoS”) requirements. For example, data may be sensitive to integrity while real-time media may be sensitive to latency. In a tunneling configuration, encapsulated media is typically communicated according to the real-time transport protocol (“RTP” as provided, for example, in IETF RFC3550).

In a TSCF tunneling configuration, RTC (e.g., speech, video, etc.) may be subject to two levels of transport: one at the outer tunnel layer typically according to TCP/TLS, and another at the inner tunnel layer typically according to UDP.FIG. 3provides example protocol layers in a TSCF tunneling configuration300for encapsulating media traffic according to an embodiment. In TSCF tunneling configuration300, compressed media (e.g., speech, video, etc.) is communicated according to RTP at the application layer, and is transported via an inner UDP at the inner transport layer within an inner IP at the inner network layer. The inner layers are within an outer TCP/TLS at the outer transport layer which is in turn within an outer IP at the outer network layer. In one embodiment, since most IP networks block any outer traffic that is not stream-based, TCP/TLS is used at the outer transport layer of TSCF tunnel108to guarantee delivery.

One disadvantage with these known systems is that using a stream-based transport (e.g., TCP/TLS) generally requires the implementation of congestion control functionality so that a reliable transport is provided while regulating throughput. However, the known systems do not provide a tunneling configuration with congestion control functionality that works across both the inner transport layer and the outer transport layer. Therefore, if the outer layers experience congestion, the inner layers are not aware of that congestion, and hence do not react accordingly. Instead, with known systems, the inner layers typically worsen the congestion of the outer layers by flooding the lower layers with packets. That is, when congestion (and consequently latency) is experienced at the outer layers of a tunnel, it is further aggravated by the continuous transmission of encapsulated media packets through the inner layers of the tunnel.

In contrast to the known systems, embodiments of the present invention provide congestion control functionality that is triggered based on the outer layers of a tunnel but is implemented at the inner layers of a tunnel. One embodiment performs early detection of congestion of RTC (e.g., speech, video, etc.) in the outer transport layer of TSCF tunnel108, and before such congestion can seriously compromise the overall quality of RTC, the embodiment triggers congestion control functionality at the inner transport layer of TSCF tunnel108.

One embodiment provides congestion control functionality by implementing a first congestion control module118at tunneling client106and a second congestion control module120at tunneling server116. In one embodiment, first congestion control module118and second congestion control module120implement circuit breakers at the inner transport layer of TSCF tunnel108such that the inner transport layer reacts to congestion as it begins to affect the outer transport layer of TSCF tunnel108.

A circuit breaker in one embodiment is a software mechanism that is used to control the flow of information in a data path in order to minimize congestion. Circuit breakers can be implemented as software modules in the transport layer of both tunneling client106and tunneling server116. Based on traffic conditions, the circuit breakers can be activated to prevent all outgoing traffic from being transmitted. When the right traffic conditions are met and the circuit breakers get activated, all outgoing traffic affected inside the tunnel is dropped in one embodiment. The traffic is not buffered since it is typically media traffic that should not be subjected to latency.

In one embodiment, one or both of first congestion control module118and second congestion control module120inspect encapsulated traffic established by an inner socket in TSCF tunnel108to identify congestion and initiate congestion control functionality on demand by triggering corresponding circuit breakers at tunneling client106or tunneling server116. A network socket is an endpoint of an inter-process communication flow across a computer network according to a communications protocol. A network socket may be a datagram socket (a connectionless network socket) or a stream socket (a connection-oriented and sequenced socket). In general, for regular communications, a user can create a datagram or stream socket that uses the network interface of the system in which the application runs. In a TSCF environment, however, sockets use a tunnel for transport instead of a network interface. To differentiate these sockets from regular sockets, they are referred to as “inner sockets” since they only exist inside a tunnel. That is, an inner socket only exists in association with a tunnel and socket traffic gets transported by the tunnel.

One embodiment provides TSCF SDKs that support an application programming interface (“API”) by which application104can enable congestion control functionality for an inner socket. For example, application104may enable circuit breaker support at tunneling client106for an inner socket by executing a corresponding “tsc_setsockopt” API with a corresponding socket option when an inner socket is created.

In one embodiment, when an inner socket in TSCF tunnel108establishes traffic, first congestion control module118and/or second congestion control module120monitor a media discontinuity period (e.g., 5 seconds) and trigger circuit breakers at both tunneling client106and tunneling server116when the media discontinuity period is above a threshold.

In an alternative or additional embodiment, when an inner socket in TSCF tunnel108establishes traffic, first congestion control module118and/or second congestion control module120check the media sending rate and trigger circuit breakers at both tunneling client106and tunneling server116accordingly. For example, first congestion control module118and/or second congestion control module120trigger respective circuit breakers if the media sending rate exceeds an estimated TCP throughput by a pre-configured factor (e.g., a factor of 10) at both tunneling client106and tunneling server116. The media sending rate corresponds to the number of tunneled bits per second. Both server116and client106independently keep track of the media sending rate as frames are encapsulated by measuring the number of bytes “B” in each frame transmitted over a period of time “T”. The media sending rate equals B×8/T. For example, for encapsulated G.711 speech, the media sending rate would be 64,000 bps.

In one embodiment, once first congestion control module118triggers a circuit breaker for an inner socket, first congestion control module118stops propagating the inner socket traffic until the measurements that triggered the circuit breaker (e.g., media discontinuity per unit of time and/or media sending rate) revert. That is, first congestion control module118stops propagating inner socket traffic until the media discontinuity per unit of time is below a corresponding threshold for the inner socket and the media sending rate does not exceed a corresponding estimated TCP throughput by a pre-configured factor for the inner socket.

Similarly, in one embodiment, once second congestion control module120triggers a circuit breaker for an inner socket, it stops propagating the inner socket traffic until the triggering measurements of media discontinuity per unit of time and/or media sending rate revert. That is, second congestion control module120stops propagating inner socket traffic until the media discontinuity per unit of time is below a corresponding threshold for the inner socket and the media sending rate does not exceed a corresponding estimated TCP throughput by a pre-configured factor for the inner socket.

In one embodiment, without application104being aware of any congestion control functionality, first congestion control module118transparently triggers circuit breakers whenever congestion is detected in encapsulated traffic in TSCF tunnel108. In an alternative or additional embodiment, first congestion control module118notifies application104whenever congestion is detected and/or congestion control functionality is enabled for encapsulated traffic in TSCF tunnel108. In one embodiment, when first congestion control module118detects congestion, it notifies application104by indicating the inner socket affected by such congestion.

One embodiment provides TSCF SDKs that support API notification for first congestion control module118to notify application104of triggering congestion control functionality in TSCF tunnel108. In one embodiment, when a circuit breaker is triggered, first congestion control module118notifies application104by executing a “tsc_notification_enable” API.

FIG. 4is an example message sequence diagram400including the sequence of messages exchanged between tunneling client106and tunneling server116for enabling/disabling circuit breakers at tunneling client106and tunneling server116, according to some embodiments.FIG. 4includes network elements such as tunneling client106and tunneling server116, as described herein with reference toFIG. 1.

At402tunneling client106sends a configuration request message to tunneling server116to establish TSCF tunnel108, and at404tunneling server116responds to the configuration request message of tunneling client106with a configuration response message. Configuration request and response messages allow for tunneling client106to obtain configuration information for TSCF tunnel108from tunneling server116, as described in, for example, 3GPP TR 33.830 V0.5.0. In one embodiment, from the RTC application perspective, application104at UE102creates TSCF tunnel108by executing a “tsc_ctrl_new_tunnel” API, and the configuration response message is sent to tunneling server116in response to the execution of this API.

Upon completing the exchange of request/response messages, tunneling client106and tunneling server116may use TSCF tunnel108for performing RTC and communicating signaling traffic and media traffic. In one embodiment, when inner signaling and media sockets are needed to place a call (e.g., for communicating SIP call control traffic or RTP media traffic), application104creates these sockets on TSCF tunnel108by executing a “tsc_socket” API. A socket is created by determining a socket type (e.g., datagram vs. stream) and a tunnel on which the socket should be created. In one embodiment, when a socket is created, application104binds the socket by executing a “tsc_bind” API. The bind function assigns a specific transport port (e.g., TCP or UDP) to the socket. This port is later used as a source port of all traffic generated by the socket. In one embodiment, if an inner socket is created in TSCF tunnel108, there is a binding at tunneling server116that links the internal IP address of TSCF tunnel108to that socket.

At406application104enables circuit breaker functionality for an inner socket in TSCF tunnel108by executing a “tsc_setsockopt” API on the inner socket. The execution of a “tsc_setsockopt” API causes first congestion control module118to send a TSCF service request message to tunneling server116to enable congestion control functionality for the inner socket at tunneling server116.

At408second congestion control module120at tunneling server116receives this service request message, determines if tunneling server116can comply with the request, and answers back to first congestion control module118with a TSCF service response message to confirm that circuit breaker functionality is enabled. Server116may not be able to comply if it does not support the functionality because it runs an older version of the software or the functionality has not been configured as described below. Subsequently, both first congestion control module118and second congestion control module120start checking for tunnel transport conditions that would trigger circuit breakers. In one embodiment, first congestion control module118and second congestion control module120trigger circuit breakers based on the media discontinuity, media sending rate, etc., as described herein with reference toFIG. 1.

At414first congestion control module118and/or second congestion control module120detect congestion of an inner socket in TSCF tunnel108based on tunnel transport conditions that would trigger circuit breakers (e.g., based on media discontinuity per unit of time, media sending rate, etc., as described herein with reference toFIG. 1).

Subsequently, at416and418first congestion control module118and/or second congestion control module120activate respective circuit breakers and stop sending media traffic over the inner socket while those conditions are met, and subsequently restart sending media traffic once the conditions are reverted.

At420, if application104issues a “tsc_setsockopt” to disable circuit breakers, first congestion control module118issues a TSCF service request message to tunneling server116to disable circuit breaker functionality, and at422second congestion control module120responds back to first congestion control module118with a corresponding TSCF service response message indicating that circuit breaker functionality has been disabled.

One embodiment supports congestion control functionality by providing a TSCF client service request message of type “Service_Type” with two TLV values indicating enablement and disablement of circuit breakers, respectively. Further, a “Connection_Info” TLV is provided to indicate source and destination transport and network endpoints. These service request types allow for tunneling client106to enable circuit breaker support at tunneling server116. Table 1 below provides example TSCF TLVs for providing congestion control services, according to some embodiments.

Example TSCF TLVs for Providing Congestion Control Services

In one embodiment, circuit breaker functionality is requested by application104by executing a “tsc_socket” API and setting a corresponding socket option as provided in the following example functionality:

In the above functionality, the “circuit_breaker” integer indicates whether circuit breaker functionality is enabled (e.g., circuit_breaker=1) or disabled (e.g., circuit_breaker=0). If “tsc_setsockopt” returns “−1,” the option has not been set correctly. If it returns “0,” the option has been set correctly but circuit breakers are not officially enabled until they are negotiated.

In one embodiment, first congestion control module118uses a “tsc_notification_circuit_breaker” notification to notify application104about enablement of circuit breakers. The following is an example functionality for enabling such notification and for providing a corresponding callback:

In the above functionality, the fourth “NULL” parameter in “tsc_notification_enable” is an opaque/private data pointer that can be recovered in the “tsc_notification_data” structure upon callback.

One embodiment provides a configuration object “tscf-interface” that includes a parameter “assigned-services” with a keyword “CB” to enable circuit breakers. Table 2 below provides an example of such TSCF configuration object for providing congestion control services, according to one embodiment.

An Example TSCF Configuration Object for Providing Congestion Control Services

The following functionality provides an example interface configuration for providing congestion control services, according to one embodiment:

The following is an example extensible markup language (“XML”) functionality for providing congestion control services, according to one embodiment:

In one embodiment, once circuit breaker functionality is enabled, the following two conditions are evaluated periodically at first congestion control module118and second congestion control module120to determine whether circuit breakers are to be triggered (e.g., enabled) or restored (e.g., disabled):If media traffic is not received during a certain time interval (e.g., typically a few seconds), the circuit breaker for the corresponding inner socket is triggered.Alternatively or additionally, circuit breakers may be triggered by using TSCF loopback packets (used to measure QoS) to periodically calculate round trip time (“RTT”) and packet loss or loss rate during a certain time interval (e.g., typically a few seconds). If the media sending rate exceeds the estimated TCP throughput by a certain factor (e.g., by a factor of 10). Loopback packets are TSCF tunneling framework packets or probes that are used to measure network impairments. They are sent by one end of the network and looped back at the other end. They have sequence number and timestamp information that allows both ends to keep track of them. A round-time trip is defined as the time a loopback packet takes to go and return to the endpoint of an original sender after being transmitted, and is measured in units of time (e.g., seconds). “Packet loss” is the probability of a loopback packet. The probability is a unit-less number between 0 (0%) and 1 (100%).

The two aforementioned conditions typically occur before the tunnel transport layer experiences congestion. Therefore, these conditions may be used to significantly reduce the effects of congestion since these conditions can provide early detection of congestion. In one embodiment, an estimated TCP throughput, T may be calculated as follows:

T=sR⁢2⁢⁢p/3(1)
where s is the average packet size, R is the RTT, value and p is the loss rate over the interval of interest (e.g., typically a few seconds).

FIG. 5is a flow diagram of congestion control module16ofFIG. 2and/or tunneling server116ofFIG. 1when performing congestion control in accordance with embodiments of the present invention. In one embodiment, the functionality of the flow diagram ofFIG. 5is implemented by software stored in memory or other computer readable or tangible medium, and executed by a processor. In other embodiments, the functionality may be performed by hardware (e.g., through the use of an application specific integrated circuit (“ASIC”), a programmable gate array (“PGA”), a field programmable gate array (“FPGA”), etc.), or any combination of hardware and software.

At504first congestion control module118at tunneling client106sends a TSCF service request to tunneling server116to enable congestion control functionality for an inner socket in TSCF tunnel108. In one embodiment, first congestion control module118sends the request when application104executes an API to enable the congestion control functionality for the inner socket.

At506second congestion control module120at tunneling server116sends a TSCF service response back to first congestion control module118to indicate that congestion control functionality is enabled for the inner socket.

At508first congestion control module118and second congestion control module120monitor congestion conditions at an outer transport layer of TSCF tunnel108for the inner socket. In one embodiment, the congestion conditions of the inner socket are based on a media discontinuity per unit of time and a media sending rate.

At510first congestion control module118and second congestion control module120execute the congestion control functionality at an inner transport layer of TSCF tunnel108based on the congestion conditions at the outer transport layer of TSCF tunnel108.

In one embodiment, the congestion control functionality implements circuit breakers at tunneling client106and tunneling server116. Accordingly, when the congestion conditions indicate congestion of the inner socket at the outer transport layer of TSCF tunnel108, the congestion control functionality activates the circuit breakers to halt communications of the inner socket at the inner transport layer of TSCF tunnel108. Further, when the congestion conditions indicate no congestion of the inner socket at the outer transport layer of TSCF tunnel108, the congestion control functionality deactivates the circuit breakers to resume the communications of the inner socket at the inner transport layer of TSCF tunnel108.

In one embodiment, upon determining congestion of the inner socket at the outer transport layer of TSCF tunnel108, first congestion control module118provides a corresponding notification to application104indicating the inner socket that is affected by congestion.

In one embodiment, first congestion control module118sends a subsequent request to second congestion control module120to disable the congestion control functionality, and second congestion control module120sends a TSCF service response back to first congestion control module118to indicate that congestion control functionality is disabled.

As disclosed, embodiments allow for a TSCF tunneling configuration that provides congestion control functionality for encapsulated media. Embodiments provide throughput throttling via circuit breakers at an inner tunnel transport layer whenever the tunneling framework starts detecting the first signs of congestion at an outer transport layer. By reducing the inner transmission rate, congestion is alleviated and recovery occurs at a much faster rate. Moreover, embodiments embed the congestion control functionality well into the tunneling configuration such that this functionality is made transparent to an RTC application. Accordingly, embodiments give the end user the possibility of improving the overall RTC quality by expediting recovery from congestion.