Patent Description:
There is increasing demand for Ethernet technology in audio-video applications. However, given the bandwidth constraints in many audio-video applications, audio-video traffic often needs to be intelligently forwarded on network links. For example, a network administrator may need to carefully plan to provision bandwidth based on the maximum number of audio-video channels supported in a network. This because the network may not be able to support unnecessary traffic on any of the links in any circumstances. Indeed, when there is unnecessary or unexpected traffic associated with a user, the audio-video quality of other users may be immediately adversely affected.

IGMP is a communications protocol used by hosts and adjacent computer network devices in Internet Protocol (IP) networks to establish multicast group memberships. IGMP facilitates IP multicast and allows the network to direct multicast transmissions to hosts that have requested them.

Moreover, 'IGMP snooping' is a process of listening to IGMP network traffic to control delivery of IP multicasts. Notably, IGMP Snooping is used to intelligently forward an audio-video channel (multicast) within a network. Computer network devices use IGMP snooping to detect or listen in on the IGMP communication or conversation between hosts, sources and computer network devices to develop or build and maintain a map of the links associated with the IP multicast transmissions for an interested receiver.

Furthermore, a host or receiver may use an IGMP report message to signal interest in receiving an audio-video channel and IGMP leave message to stop receiving an audio-video channel. However, a leave message does not typically immediately stop the audio-video channel from a source that is connected to a computer network device, such as a switch.

This is illustrated in <FIG>, which presents an existing network. Notably, a querier switch <NUM> (which is connected to multiple sources <NUM>) may not know how many receivers <NUM> are beyond switch <NUM> and/or their status (such as whether or not they are sleeping), and thus may not be able to immediately stop traffic, e.g., when it receives a leave message from a given receiver, such as receiver <NUM>-<NUM>. Instead, in order to detect the presence of other receivers <NUM>, querier switch <NUM> may use two group-specific query messages with an interval of <NUM>. The query messages may trigger the interested receivers <NUM> to send responses or report messages. If no response is received, then querier switch <NUM> stops forwarding on the audio-video channel on that link. However, the resulting delay may saturate the link bandwidth between querier switch <NUM> and switch <NUM>, and may adversely impact the overall quality-of-service (QoS) of the audio-video deployment.

In order to make the problem clearer, assume that a network administrator has provisioned sufficient bandwidth to carry only two audio-video channels for two receivers, such as receiver <NUM>-<NUM> and <NUM>-<NUM>. Thus, receiver <NUM>-<NUM> and receiver <NUM>-<NUM> may respectively view two audio-video channels.

Subsequently, a user of receiver <NUM>-<NUM> may switch the audio-video channel by, e.g., pressing a button on their remote control. This audio-video channel switching may result in a leave message (to leaving the old audio-video channel) followed by a report message (to request for the new audio-video channel). In response to the leave message, querier switch <NUM> may follow a standard IGMP procedure of waiting more than two seconds before stopping the audio-video channel. However, the report message may trigger querier switch <NUM> to immediately start sending the new audio-video channel data on the link.

Consequently, for the time period of processing of the leave message, the link will be saturated with data for three audio-video channels (two old and one new audio-video channel). This extra data will cause jitter on the display screens of receiver <NUM>-<NUM> for <NUM> to <NUM> seconds and <NUM> to <NUM> seconds of delay for receiver <NUM>-<NUM> to receive the new audio-video channel. These problems will be compounded if the users of either receiver <NUM>-<NUM> or <NUM>-<NUM> is impatient and frequently switches audio-video channels.

In principle, these problems can be addressed by increasing the bandwidth of the link. However, in practice this approach is typically undesirable, because there may be multiple receivers and audio-video channels in a given network. Thus, in this approach, the network may need to overprovisioned or all of the receivers may have degraded QoS. Alternatively, in principle IGMPv3 may be implemented and used to enable host tracking. However, in practice this approach requires an expensive and complicated upgrade of the receivers. <CIT> discloses a further prior art example of replication management for a remote multicast replication network. <CIT> discloses a prior art example of a method and system for multicast traffic reduction. <CIT> discloses a prior art example of facilitating accelerated processing of internet group management protocol messages.

The invention is disclosed according to a device as disclosed in independent claim <NUM>, a non-transitory computer-readable storage medium according to independent claim <NUM> and a method according to independent claim <NUM>. Additional aspects of the invention are disclosed in the dependent claims.

A computer network device (such as a switch or a router) that implements host tracking is described. This computer network device may include: an interface circuit; a processor; and a memory that stores program instructions, where, when executed by the processor, the program instructions cause the computer network device to perform operations. Notably, during operation, the computer network device receives a report message that is associated with a host (or receiver), which indicates the host wants to join a group in a network that receives an audio-video channel from a source.

Note that the report message may be selectively flooded within the network (e.g., on non-edge ports). Moreover, the leave message may be selectively flooded within the network (e.g., on the non-edge ports). Thus, the computer network device may provide the report message or the leave message to one or more other computer network devices in the network via the non-edge ports. However, the flooding of the report message or the leave message may exclude forwarding to edge ports associated with the one or more hosts or the source.

Furthermore, the report message and the leave message may be compatible with an IGMP. For example, the IGMP may be IGMPv2. In some embodiments, the computer network device implements IGMPv2. Alternatively or additionally, the computer network device may not implement IGMPv3.

In some embodiments, the computer network device may dynamically determine non-edge ports within the network and edge ports associated with the one or more hosts or the source using a passive IGMP snooping neighbors protocol. Notably, the computer network device may exchange network messages (such as passive neighbor messages) with the one or more other computer network devices in the network on a type of port (such as a router port). However, the network messages may not be forwarded to the source or the one or more hosts. When the computer network device receives a given network message, the computer network device may mark one or more associated receive ports as being associated with a passive neighbor (e.g., as a passive neighbor port). The computer network device may use this information to determine a network topology, including the edge ports (to the source and the one or more hosts) and the non-edge ports (to the one or more other computer network devices). Moreover, the computer network device may use the determined edge ports to suppress or not forward the report message or the leave message to the one or more hosts or the source. Note that the network messages may be exchanged periodically, such as after a predefined time interval (such as <NUM>) during which the computer network device listens for communication associated with the one or more hosts (such as a response associated with a given host in the one or more hosts).

Alternatively or additionally, the computer network device may be manually configured with information specifying the edge ports and the non-edge ports.

Moreover, the computer network device may stop the forwarding of the audio-video channel from the source without first providing a group-specific query message addressed to the one or more hosts in the group.

Another embodiment provides a computer-readable storage medium for use with the computer network device. When executed by the computer network device, this computer-readable storage medium causes the computer network device to perform at least some of the aforementioned operations.

Another embodiment provides a method, which may be performed by the computer network device. This method includes at least some of the aforementioned operations.

Note that like reference numerals refer to corresponding parts throughout the drawings. Moreover, multiple instances of the same part are designated by a common prefix separated from an instance number by a dash.

A computer network device (such as a switch or a router) that implement host tracking is described. During operation, the computer network device may receive a report message that is associated with a host, which indicates that the host wants to join a group in a network that receives an audio-video channel from a source. In response, the computer network device may add information associated with the host to a group data structure associated with one or more hosts in the group. Then, when the computer network device receives a leave message that is associated with the host, the computer network device may remove or deactivates the host from the group data structure. Moreover, when the group data structure is empty (has no hosts) or has no active hosts, the computer network device may stop forwarding the audio-video channel from the source to the group without further delay. For example, the computer network device may stop the forwarding without first providing a group-specific query message addressed to the one or more hosts in the group. Note that the report message and the leave message may be compatible with IGMPv2, and the computer network device may implement IGMPv2.

By maintaining the group data structure, these communication techniques may allow the computer network device to rapidly respond to the leave message. Notably, by avoiding the usual delay is processing of the leave message, the communication techniques may avoid link saturation, increased jitter and decreased QoS. Moreover, the communication techniques may reduce or eliminate the problems associated with the usual processing delay without requiring the use of overprovisioned links and/or the use of IGMPv3. Instead, the communication techniques may allow host tracking to be implemented using IGMPv2. Consequently, the communication techniques may improve the performance of the computer network device and/or the network that includes the computer network device.

In the discussion that follows, an access point and/or an electronic device (such as a recipient electronic device, which is sometimes referred to as a 'client') may communicate packets or frames in accordance with a wireless communication protocol, such as an Institute of Electrical and Electronics Engineers (IEEE) <NUM> standard (which is sometimes referred to as 'Wi-Fi,' from the Wi-Fi Alliance of Austin, Texas), Bluetooth (from the Bluetooth Special Interest Group of Kirkland, Washington), and/or another type of wireless interface. In the discussion that follows, Wi-Fi is used as an illustrative example. For example, an IEEE <NUM> standard may include one or more of: IEEE <NUM>. 11a, IEEE <NUM>. 11b, IEEE <NUM>, IEEE <NUM>-<NUM>, IEEE <NUM>. 11n, IEEE <NUM>-<NUM>, IEEE <NUM>-<NUM>, IEEE <NUM>. 11ac, IEEE <NUM>. 11ax, IEEE <NUM>1ba, IEEE <NUM>1be, or other present or future developed IEEE <NUM> technologies.

However, a wide variety of communication protocols (such as Long Term Evolution or LTE, another cellular-telephone communication protocol, etc.) may be used. The wireless communication may occur in one or more bands of frequencies, such as: a <NUM>, a <NUM>, a <NUM>, <NUM>, the Citizens Broadband Radio Spectrum or CBRS (e.g., a frequency band near <NUM>), a band of frequencies used by LTE or another cellular-telephone communication protocol or a data communication protocol, and/or a <NUM> frequency band. (Note that IEEE <NUM>. 11ad communication over a <NUM> frequency band is sometimes referred to as 'WiGig. ' In the present discussion, these embodiments also encompassed by 'Wi-Fi. ') In some embodiments, communication between electronic devices may use multi-user transmission (such as orthogonal frequency division multiple access or OFDMA).

Moreover, the electronic device and/or the access point may communicate with one or more other access points and/or computers in a network using a wireless or a wired communication protocol, such as an IEEE <NUM> standard, an IEEE <NUM> standard (which is sometimes referred to as 'Ethernet') and/or another type of wired or wireless interface. In the discussion that follows, Ethernet is used as an illustrative example of communication between the electronic device and/or the access point and the one or more other access points and/or computers in the network.

<FIG> presents a block diagram illustrating an example of communication among one or more access points <NUM> and electronic devices <NUM> (such as a cellular telephone, and which are sometimes referred to as 'clients') in a WLAN <NUM> (which is used as an example of a network) in accordance with some embodiments. Access points <NUM> may communicate with each other in WLAN <NUM> using wireless and/or wired communication (such as by using Ethernet or a communication protocol that is compatible with Ethernet). Note that access points <NUM> may include a physical access point and/or a virtual access point that is implemented in software in an environment of an electronic device or a computer. In addition, at least some of access points <NUM> (such as access points <NUM>-<NUM> and <NUM>-<NUM>) may communicate with electronic devices <NUM> using wireless communication.

The wired and/or wireless communication among access points <NUM> in WLAN <NUM> may occur via network <NUM> (such as an intra-net, a mesh network, point-to-point connections and/or the Internet) and may use a network communication protocol, such as Ethernet. For example, WLAN <NUM> may include computer network devices (CND) <NUM> (e.g., a switch or a router). In some embodiments, the one or more computer network device <NUM> may include a stack of multiple computer network devices (which are sometimes referred to as 'stacking units').

Furthermore, the wireless communication using Wi-Fi may involve: transmitting advertising frames on wireless channels, detecting one another by scanning wireless channels, establishing connections (for example, by transmitting association or attach requests), and/or transmitting and receiving packets or frames (which may include the association requests and/or additional information as payloads). In some embodiments, the wired and/or wireless communication among access points <NUM> also involves the use of dedicated connections, such as via a peer-to-peer (P2P) communication technique. Therefore, access points <NUM> may support wired communication outside of WLAN <NUM> (such as Ethernet) and wireless communication within WLAN <NUM> (such as Wi-Fi), and one or more of access points <NUM> may also support a wired communication protocol for communicating via network <NUM> with electronic devices (such as a computer <NUM> or a controller <NUM> of WLAN <NUM>, which may be remoted located from WLAN <NUM>).

As described further below with reference to <FIG>, the one or more computer network device <NUM>, access points <NUM> and/or electronic devices <NUM> may include subsystems, such as a networking subsystem, a memory subsystem and a processor subsystem. In addition, access points <NUM> and electronic devices <NUM> may include radios <NUM> in the networking subsystems. More generally, access points <NUM> and electronic devices <NUM> can include (or can be included within) any electronic devices with the networking subsystems that enable access points <NUM> and electronic devices <NUM> to communicate with each other using wireless and/or wired communication. This wireless communication can comprise transmitting advertisements on wireless channels to enable access points <NUM> and/or electronic devices <NUM> to make initial contact or detect each other, followed by exchanging subsequent data/management frames (such as association requests and responses) to establish a connection, configure security options (e.g., Internet Protocol Security), transmit and receive packets or frames via the connection, etc. Note that while instances of radios <NUM> are shown in access points <NUM> and electronic devices <NUM>, one or more of these instances may be different from the other instances of radios <NUM>.

As can be seen in <FIG>, wireless signals <NUM> (represented by a jagged line) are transmitted from radio <NUM>-<NUM> in access point <NUM>-<NUM>. These wireless signals may be received by radio <NUM>-<NUM> in electronic device <NUM>-<NUM>. Notably, access point <NUM>-<NUM> may transmit packets or frames. In turn, these packets or frames may be received by electronic device <NUM>-<NUM>. Moreover, access point <NUM>-<NUM> may allow electronic device <NUM>-<NUM> to communicate with other electronic devices, computers and/or servers via networks <NUM> and/or <NUM>.

Note that the communication among access points <NUM> and/or with electronic devices <NUM> (and, more generally, communication among components in WLAN <NUM>) may be characterized by a variety of performance metrics, such as: a received signal strength (RSSI), a data rate, a data rate for successful communication (which is sometimes referred to as a 'throughput'), an error rate (such as a retry or resend rate), a mean-square error of equalized signals relative to an equalization target, intersymbol interference, multipath interference, a signal-to-noise ratio, a width of an eye pattern, a ratio of number of bytes successfully communicated during a time interval (such as <NUM>-<NUM>) to an estimated maximum number of bytes that can be communicated in the time interval (the latter of which is sometimes referred to as the 'capacity' of a communication channel or link), and/or a ratio of an actual data rate to an estimated data rate (which is sometimes referred to as 'utilization').

In the described embodiments processing a packet or frame in access points <NUM> and electronic devices <NUM> includes: receiving signals (such as wireless signals <NUM>) corresponding to the packet or frame; decoding/extracting the packet or frame from received wireless signals <NUM> to acquire the packet or frame; and processing the packet or frame to determine information contained in the packet or frame.

Although we describe the network environment shown in <FIG> as an example, in alternative embodiments, different numbers or types of electronic devices may be present. For example, some embodiments comprise more or fewer electronic devices. As another example, in another embodiment, different electronic devices are transmitting and/or receiving packets or frames.

As noted previously, the absence of host tracking (e.g., in existing implementations of IGMPv2) often result in delays, jitter and reduced QoS of audio-video channels in IP networks. Moreover, it is often difficult to segregate edge ports and non-edge ports using existing IGMP snooping techniques. Consequently, many existing computer network devices are unable to support advanced features, which can degrade performance of the computer network devices and/or networks that include the computer network devices.

As described further below with reference to <FIG>, in order to address these problems, computer network devices <NUM> may implement host tracking and/or a passive snooping neighbors protocol. In the discussion that follows, IGMP snooping is used as an illustrative example. However, in other embodiments, another communication protocol may be used to facilitate passive neighbors discovery.

Notably, the communication techniques may allow a computer network device (such as computer network device <NUM>-<NUM>) that implements IGMP snooping to segregate edge ports (such as ports connected to a host or a source in a network) from non-edge ports (such as ports connected to other computer network devices <NUM> in the network) and, more generally, to compute or determine a topology of the network. Moreover, the communication techniques may allow computer network device <NUM>-<NUM> to identify one or more ports (such as router ports) associated with other computer network devices (such as computer network device <NUM>-<NUM>) in the network that implement IGMP snooping. These capabilities of computer network device <NUM>-<NUM> may be facilitated by monitoring communication in the network (such as IGMP messages, e.g., IGMP report or leave messages, IGMP group addressed messages, IGMP queries, etc.) and periodically exchanging messages (such as passive monitoring messages) in the network with, e.g., computer network device <NUM>-<NUM> in the network, via as associated port. Note that an IGMP group addressed message may include: a source Internet Protocol address, an IGMP type, a group address, and/or other information.

Using the communication techniques, computer network device <NUM>-<NUM> may identify non-edge electronic devices in the network (such as computer network device <NUM>-<NUM>). Notably, computer network device <NUM>-<NUM> may declare or notify computer network device <NUM>-<NUM> that it is a passive IGMP snooping neighbor (PIGSN), i.e., that it implements the passive IGMP snooping protocol, by periodically providing passive network messages on a port associated with a link with computer network device <NUM>-<NUM>. Similarly, computer network device <NUM>-<NUM> may declare or notify computer network device <NUM>-<NUM> that it is a PIGSN by periodically providing passive network messages on a port associated with a link with computer network device <NUM>-<NUM>. Note that the periodically exchanged passive network messages may be provided after a time interval (such as, e.g., <NUM>).

When a given computer network device (such as computer network device <NUM>-<NUM>) receives a passive neighbor message on a port, it may note or mark that this port is associated with a PIGSN (and that it is a non-edge port). Moreover, computer network device <NUM>-<NUM> may not forward the passive neighbor message to other computer network devices <NUM> in the network.

Similarly, after a time interval (such as, e.g., <NUM>) has elapsed, computer network device <NUM>-<NUM> may send a second passive neighbor message to computer network device <NUM>-<NUM> via the same or another port. When computer network device <NUM>-<NUM> receives this second passive neighbor message on a second port, it may note or mark that the second port is associated with a PIGSN (and that it is a non-edge port). Once again, computer network device <NUM>-<NUM> may not forward the second passive neighbor message to other computer network devices <NUM> in the network. Thus, the passive neighbor messages may not be propagated across the network.

Moreover, when computer network device <NUM>-<NUM> receives another type of message (such as an IGMP report or leave message, which may be an IGMP group addressed message) via another port from a host (such as one of electronic devices <NUM>) in the network, computer network device <NUM>-<NUM> may provide the other type of message to the other computer network devices <NUM> via PIGSN ports. However, computer network device <NUM>-<NUM> may suppress forwarding of the other type of message to the host. Thus, the computer network device may selectively provide or forward the other type of message based at least in part on identified PIGSN ports or the non-edge ports in the network. In some embodiments, the other type of message is received by computer network device <NUM>-<NUM> from a querier in the network (e.g., computer network device <NUM>-<NUM>), which may be a central point in a multicast group in the network that is coupled or connected to the host.

Alternatively or additionally, computer network devices <NUM> may implement host tracking. In some embodiments, the host tracking is enabled or facilitated by the passive snooping neighbors protocol.

Notably, a given one of computer network devices <NUM> (such as computer network device <NUM>-<NUM>) may receive a report message (such as an IGMP report message, e.g., an IGMPv2 report message) from a host or receiver (such as electronic device <NUM>-<NUM>), which indicates that the host wants to join a group in a network that receives an audio-video channel from a source (such as computer <NUM>). In response, computer network device <NUM>-<NUM> may add information associated with the host to a group data structure associated with one or more hosts in the group. For example, the information may include a network path or link associated with the host, a port associated with the network path or link, and/or an identifier of the host (such as an IP address of the host).

Then, when computer network device <NUM>-<NUM> receives a leave message (such as an IGMP leave message, e.g., an IGMPv2 leave message) from the host, computer network device <NUM>-<NUM> may remove or deactivate the host from the group data structure. Moreover, when the group data structure is empty (has no hosts) or has no active hosts, computer network device <NUM>-<NUM> may stop forwarding the audio-video channel from the source to the group without further delay. For example, computer network device <NUM>-<NUM> may stop the forwarding of the audio-video channel from the source without first providing a group-specific query message addressed to the one or more hosts in the group.

Note that the report message may be selectively flooded within the network (e.g., on non-edge ports). Moreover, the leave message may be selectively flooded within the network (e.g., on the non-edge ports). Thus, computer network device <NUM>-<NUM> may provide the report message or the leave message to one or more other computer network devices <NUM> in the network via the non-edge ports. However, the flooding of the report message or the leave message may exclude forwarding to edge ports associated with the one or more hosts or the source. The selective forwarding may be based at least in part on the network information or network topology (such as the edge and the non-edge ports in the network) that is learned by computer network device <NUM>-<NUM> using the passive snooping neighbors protocol. Alternatively or additionally, computer network device <NUM>-<NUM> may be manually configured (e.g., by a network administrator) with information specifying the edge ports and the non-edge ports.

In some embodiments, computer network device <NUM>-<NUM> implements IGMPv2. Alternatively or additionally, computer network device <NUM>-<NUM> may not implement or may not be compatible with IGMPv3.

In these ways, computer network devices <NUM> may identify PIGSNs in the network (and, thus, the edge ports and non-edge ports in the network). More generally, computer network devices <NUM> may compute or determine a topology of the network based at least in part on the exchanged passive neighbor messages and the associated ports. Furthermore, computer network devices <NUM> may implement host tracking without requiring an upgrade to IGMPv3. These capabilities may allow computer network devices <NUM> to reduce or eliminate the bandwidth-saturation problem, and thus to provide improved performance and QoS (such as avoiding delays and jitter), and to support advanced features. Therefore, the communication techniques may improve the user experience when using computer network devices <NUM> and/or the network that includes computer network devices <NUM>.

We now describe embodiments of a method. <FIG> presents a flow diagram illustrating an example of a method <NUM> for performing host tracking in accordance with some embodiments. This method may be performed by a computer network device (such as one of computer network devices <NUM> in <FIG>).

During operation, the computer network device (such as a router or a switch) may receive a report message (operation <NUM>) that is associated with a host (or receiver), which indicates that the host wants to join a group in a network that receives an audio-video channel from a source.

In response, the computer network device may add information associated with the host to a group data structure (operation <NUM>) associated with one or more hosts in the group.

Then, when the computer network device receives a leave message (operation <NUM>) that is associated with the host, the computer network device may remove (operation <NUM>) or deactivates the host from the group data structure.

Moreover, when the group data structure is empty (operation <NUM>) or has no active hosts, the computer network device may stop forwarding the audio-video channel (operation <NUM>) from the source to the group without further delay. For example, the computer network device may stop the forwarding of the audio-video channel from the source without first providing a group-specific query message addressed to the one or more hosts in the group. Otherwise, the computer network device may continue (operation <NUM>) to forward the audio-video channel.

In some embodiments, the computer network device may optionally perform one or more additional operations (operation <NUM>). For example, the computer network device may selectively forward or flood the report message and/or the leave message within the network (e.g., on non-edge ports). Thus, the computer network device may provide the report message or the leave message to one or more other computer network devices in the network via the non-edge ports. However, the flooding of the report message or the leave message may exclude forwarding to edge ports associated with the one or more hosts or the source.

Note that the dynamic determining of the edge ports and/or the non-edge ports may be useful for the host tracking. Notably, because IGMPv2 supports report suppression, if a given report message is forwarded on edge ports where the one or more hosts are connected, a corresponding host will suppress its own report message. This will result in report misses in the network and traffic disturbances. The passive IGMP snooping neighbors protocol allows internal links (and, thus, non-edge ports) to be identified and segregated from host links (and, thus, edge ports). Because of the IGMPv2 host tracking, the computer network device knows exactly how many receivers a group has on a link. Therefore, the computer network devices does not need to depend on an IGMP group-specific message (such as a query message) to detect the other receivers. Consequently, the use of IGMP group-specific query messages can be eliminated from the network.

In some embodiments of method <NUM>, there may be additional or fewer operations. Furthermore, the order of the operations may be changed, and/or two or more operations may be combined into a single operation.

<FIG> presents a drawing illustrating an example of communication among electronic device <NUM>-<NUM> (or a host), computer network devices <NUM> and computer <NUM> (or a source) in a network in accordance with some embodiments. Notably, an interface circuit (IC) <NUM> in electronic device (ED) <NUM>-<NUM> may send a report message (RM) <NUM> to computer network device <NUM>-<NUM>, which includes information <NUM> indicates that electronic device <NUM>-<NUM> wants to join a group in a network that receives an audio-video channel from computer <NUM>.

After receiving report message <NUM>, an interface circuit <NUM> in computer network device <NUM>-<NUM> may provide information <NUM> to a processor <NUM> in computer network device <NUM>-<NUM>. Processor <NUM> may add information <NUM> associated with electronic device <NUM>-<NUM> to a group data structure (GDS) <NUM> associated with one or more hosts in the group, which is stored in memory <NUM> in computer network device <NUM>-<NUM>. Moreover, processor <NUM> may instruct <NUM> interface circuit <NUM> to forward an audio-video channel (AVC) <NUM> from computer <NUM> to electronic device <NUM>-<NUM>.

Subsequently, interface circuit <NUM> may send a leave message (LM) <NUM> to computer network device <NUM>-<NUM>. After receiving leave message <NUM>, interface circuit <NUM> may provide information <NUM> corresponding to leave message <NUM> to processor <NUM>. Based at least in part on information <NUM>, processor <NUM> may remove <NUM> or deactivate electronic device <NUM>-<NUM> from group data structure <NUM> in memory <NUM>. Moreover, when group data structure <NUM> is empty (has no hosts) or has no active hosts, processor <NUM> may instruct <NUM> interface circuit <NUM> to stop forwarding audio-video channel <NUM> from computer <NUM> to electronic device <NUM>-<NUM> without further delay (as opposed to first providing a group-specific query message addressed to the one or more hosts in the group). Thus, computer network device <NUM>-<NUM> may immediately stop forwarding audio-video channel <NUM> from computer <NUM> to electronic device <NUM>-<NUM>.

While <FIG> illustrates communication between components using unidirectional or bidirectional communication with lines having single arrows or double arrows, in general the communication in a given operation in these figures may involve unidirectional or bidirectional communication.

<FIG> presents a block diagram illustrating an example of a passive IGMP snooping neighbors protocol in a network in accordance with some embodiments. The network illustrated in <FIG> includes computer network devices <NUM>, a source <NUM>, and receivers (or hosts) <NUM> in one or more multicast groups.

Computer network devices <NUM> may obtain information about the network via IGMP queries and responses or reports. For example, computer network device <NUM>-<NUM>, which is coupled or connected to source <NUM>, may provide IGMP queries to computer network devices <NUM>-<NUM> and <NUM>-<NUM>. (However, computer network device <NUM>-<NUM> may not provide IGMP queries to source <NUM>. Instead, computer network device <NUM>-<NUM> may be a querier in the network. In response to IGMP queries, computer network devices <NUM>-<NUM> and <NUM>-<NUM> may provide IGMP reports. Receivers <NUM> may provide IGMP report or leave messages. ) Then, computer network device <NUM>-<NUM> forwards an IGMP report to receiver <NUM>-<NUM>. Moreover, computer network device <NUM>-<NUM> forwards an IGMP report to computer network device <NUM>-<NUM>, which forwards an IGMP report to receiver <NUM>-<NUM>. Note that one or more of receivers <NUM> may suppress reports, i.e., they may not respond to IGMP queries or reports. This may prevent computer network devices <NUM> from determining membership in the one or more multicast groups.

In the passive IGMP snooping neighbors protocol, PIGSNs are non-querier computer network devices <NUM>-<NUM>, <NUM>-<NUM> and <NUM>-<NUM>. These computer network devices may perform the following operations. When computer network devices <NUM>-<NUM>, <NUM>-<NUM> and <NUM>-<NUM> detect that they are PIGSNs, they start sending passive neighbor messages to each other on router ports. The passive neighbor messages do not propagate across the network, e.g., to source <NUM> or receivers <NUM>. The computer network devices <NUM>-<NUM>, <NUM>-<NUM> and <NUM>-<NUM> that receive an instance of a passive neighbor message may mark the receive port(s) as being associated with a passive neighbor.

Using the passive IGMP snooping neighbors protocol, each of computer network devices <NUM>-<NUM>, <NUM>-<NUM> and <NUM>-<NUM> may build knowledge of the presence of a querier (such as computer network device <NUM>-<NUM>), passive neighbors on each of its ports and, thus, the topology of the network. Thus, computer network devices <NUM>-<NUM>, <NUM>-<NUM> and <NUM>-<NUM> may compute which ports are edge-ports and which are non-edge ports. For example, information about the network topology shown in <FIG> is summarized in Table <NUM>. This information may allow computer network devices <NUM>-<NUM>, <NUM>-<NUM> and <NUM>-<NUM> to suppress forwarding of an IGMP report or leave message on a port to source <NUM> or receivers <NUM>-<NUM>. Instead, computer network devices <NUM>-<NUM>, <NUM>-<NUM> and <NUM>-<NUM> may selectively forward or flood the IGMP query or IGMP report or leave messages within the network. Moreover, using the computed information, a given computer network device in the network may dynamically enable support for advance features. In some embodiments, an advanced feature may include SDVoE flooding reports on or restricted to non-edge ports in the network. This may avoid manual configuration or intervention and may help a network administrator to more easily deploy SDVoE.

In an existing IGMP communication protocol, a querier switch (or router) may periodically send IGMP query messages. Other switches receiving such an IGMP query message may marks the associated ports/link as a router port and may mark themselves as passive switch. Then, the other switches may forward the IGMP query message to other ports.

In the passive IGMP snooping neighbors protocol, a switch (or a router) implementing the protocol may sends IGMP passive neighbor messages periodically on one or more router ports. Another switch receiving one of the IGMP passive neighbor messages may mark the associated ports/links as being passive neighbor port(s). This switch may not forward this IGMP passive neighbor message to other ports. Moreover, other passive switches in a network may repeat these operations to implement passive neighbors protocol.

By performing the passive IGMP snooping neighbors protocol, the switches (and/or routers) in the network may learn or identify: non-edge-ports (ports marked as a router port and a passive neighbor port); and edge-ports (ports not marked as a router port and a passive neighbor port). Using this knowledge, IGMP report or leave messages sent by a receiver or a host can be efficiently flooded and restricted only on the non-edge-ports. This capability may help implementation of enhanced features, such as SDVoE, IGMP v2 true fast leave, etc., without manual intervention.

Note that some embodiments of the communication techniques may be used in conjunction with other features or aspects of Internet Protocol v6 (IPV6), such as multicast listener discovery snooping.

<FIG> presents a block diagram illustrating an example of host tracking in a network using IGMPv2. In order to support IGMPv2 host tracking following procedure may be implemented. Notably, an IGMP report message from receiver <NUM>-<NUM> may be flooded in the network. This IGMP report message may indicate that receiver <NUM>-<NUM> wants to join a group of one or more hosts that receives an audio-video channel (and, more generally, content or data) from source <NUM>. Each of switches <NUM> and <NUM> may receive the report message and may build its group data structure with host information about receiver <NUM>-<NUM>. For example, group data structure <NUM>-<NUM> in switch <NUM> may specify the ports associated with receivers <NUM> and identifiers of receivers <NUM>, and group data structure <NUM>-<NUM> in switch <NUM> may specify the ports to switch <NUM>, which is associated with receivers <NUM>, as well as the identifiers of receivers <NUM>.

Subsequently, when an IGMP leave message from receiver <NUM>-<NUM> is flooded in the network, each of switches <NUM> and <NUM> may receive the leave message and may remove the corresponding host (receiver <NUM>-<NUM>) from group data structures <NUM>. If a group data structure (such as data structure <NUM>-<NUM>) becomes empty, the corresponding switch (such as switch <NUM>) may immediately stop forwarding the audio-video channel (i.e., without further delay, such as the delay associated with an IGMP query message to receivers <NUM>).

Note that because IGMPv2 supports report suppression, report messages should not be forwarded on edge ports in the network where receivers <NUM> are connected. Otherwise, receivers <NUM> will suppress their own report messages, which may result in report misses in the network and, thus, traffic disturbance. For example, if receiver <NUM>-<NUM> sends a report message that is forwarded by receiver <NUM>-<NUM>, then receiver <NUM>-<NUM> will suppress its interest in joining the group.

In order to dynamically determine internal links and segregate the host links connected to a given switch (such as switch <NUM>), IGMPv2 host tracking may leverage the network information determined using PIGSN and/or may be provisioned manually via user configuration. Because IGMPv2 host tracking enables switches <NUM> and <NUM> to know exactly how many receivers <NUM> there are in a group on a link, switches <NUM> and <NUM> do not need to depend on IGMP group-specific query messages to detect other receivers <NUM>. Consequently, the disclosed communication techniques may eliminate the use of group-specific query messages from the network, and may reduce or eliminate the bandwidth-saturation problem.

We now describe embodiments of an electronic device, which may perform at least some of the operations in the communication techniques. <FIG> presents a block diagram illustrating an example of an electronic device <NUM> in accordance with some embodiments, such as one of computer <NUM>, one of computer network devices <NUM>, controller <NUM>, one of access points <NUM> or one of electronic devices <NUM>. This electronic device includes processing subsystem <NUM>, memory subsystem <NUM>, and networking subsystem <NUM>. Processing subsystem <NUM> includes one or more devices configured to perform computational operations. For example, processing subsystem <NUM> can include one or more microprocessors, ASICs, microcontrollers, programmable-logic devices, one or more graphics process units (GPUs) and/or one or more digital signal processors (DSPs).

Memory subsystem <NUM> includes one or more devices for storing data and/or instructions for processing subsystem <NUM> and networking subsystem <NUM>. For example, memory subsystem <NUM> can include dynamic random access memory (DRAM), static random access memory (SRAM), and/or other types of memory. In some embodiments, instructions for processing subsystem <NUM> in memory subsystem <NUM> include: one or more program modules or sets of instructions (such as program instructions <NUM> or operating system <NUM>), which may be executed by processing subsystem <NUM>. Note that the one or more computer programs may constitute a computer-program mechanism. Moreover, instructions in the various modules in memory subsystem <NUM> may be implemented in: a high-level procedural language, an object-oriented programming language, and/or in an assembly or machine language. Furthermore, the programming language may be compiled or interpreted, e.g., configurable or configured (which may be used interchangeably in this discussion), to be executed by processing subsystem <NUM>.

In addition, memory subsystem <NUM> can include mechanisms for controlling access to the memory. In some embodiments, memory subsystem <NUM> includes a memory hierarchy that comprises one or more caches coupled to a memory in electronic device <NUM>. In some of these embodiments, one or more of the caches is located in processing subsystem <NUM>.

In some embodiments, memory subsystem <NUM> is coupled to one or more high-capacity mass-storage devices (not shown). For example, memory subsystem <NUM> can be coupled to a magnetic or optical drive, a solid-state drive, or another type of mass-storage device. In these embodiments, memory subsystem <NUM> can be used by electronic device <NUM> as fast-access storage for often-used data, while the mass-storage device is used to store less frequently used data.

Networking subsystem <NUM> includes one or more devices configured to couple to and communicate on a wired and/or wireless network (i.e., to perform network operations), including: control logic <NUM>, an interface circuit <NUM> and one or more antennas <NUM> (or antenna elements). (While <FIG> includes one or more antennas <NUM>, in some embodiments electronic device <NUM> includes one or more nodes, such as nodes <NUM>, e.g., a network node that can be coupled or connected to a network or link, or an antenna node, connector or a metal pad that can be coupled to the one or more antennas <NUM>. Thus, electronic device <NUM> may or may not include the one or more antennas <NUM>. ) For example, networking subsystem <NUM> can include a Bluetooth™ networking system, a cellular networking system (e.g., a <NUM>/<NUM>/<NUM> network such as UMTS, LTE, etc.), a universal serial bus (USB) networking system, a networking system based on the standards described in IEEE <NUM> (e.g., a Wi-Fi® networking system), an Ethernet networking system, a cable modem networking system, and/or another networking system.

Note that a transmit or receive antenna pattern (or antenna radiation pattern) of electronic device <NUM> may be adapted or changed using pattern shapers (such as reflectors) in one or more antennas <NUM> (or antenna elements), which can be independently and selectively electrically coupled to ground to steer the transmit antenna pattern in different directions. Thus, if one or more antennas <NUM> include N antenna pattern shapers, the one or more antennas may have <NUM>N different antenna pattern configurations. More generally, a given antenna pattern may include amplitudes and/or phases of signals that specify a direction of the main or primary lobe of the given antenna pattern, as well as so-called 'exclusion regions' or 'exclusion zones' (which are sometimes referred to as 'notches' or 'nulls'). Note that an exclusion zone of the given antenna pattern includes a low-intensity region of the given antenna pattern. While the intensity is not necessarily zero in the exclusion zone, it may be below a threshold, such as 3dB or lower than the peak gain of the given antenna pattern. Thus, the given antenna pattern may include a local maximum (e.g., a primary beam) that directs gain in the direction of electronic device <NUM> that is of interest, and one or more local minima that reduce gain in the direction of other electronic devices that are not of interest. In this way, the given antenna pattern may be selected so that communication that is undesirable (such as with the other electronic devices) is avoided to reduce or eliminate adverse effects, such as interference or crosstalk.

Networking subsystem <NUM> includes processors, controllers, radios/antennas, sockets/plugs, and/or other devices used for coupling to, communicating on, and handling data and events for each supported networking system. Note that mechanisms used for coupling to, communicating on, and handling data and events on the network for each network system are sometimes collectively referred to as a 'network interface' for the network system. Moreover, in some embodiments a 'network' or a 'connection' between the electronic devices does not yet exist. Therefore, electronic device <NUM> may use the mechanisms in networking subsystem <NUM> for performing simple wireless communication between the electronic devices, e.g., transmitting advertising or beacon frames and/or scanning for advertising frames transmitted by other electronic devices as described previously.

Within electronic device <NUM>, processing subsystem <NUM>, memory subsystem <NUM>, and networking subsystem <NUM> are coupled together using bus <NUM>. Bus <NUM> may include an electrical, optical, and/or electro-optical connection that the subsystems can use to communicate commands and data among one another. Although only one bus <NUM> is shown for clarity, different embodiments can include a different number or configuration of electrical, optical, and/or electro-optical connections among the subsystems.

In some embodiments, electronic device <NUM> includes a display subsystem <NUM> for displaying information on a display, which may include a display driver and the display, such as a liquid-crystal display, a multi-touch touchscreen, etc..

Electronic device <NUM> can be (or can be included in) any electronic device with at least one network interface. For example, electronic device <NUM> can be (or can be included in): a desktop computer, a laptop computer, a subnotebook/netbook, a server, a tablet computer, a smartphone, a cellular telephone, a smartwatch, a consumer-electronic device, a portable computing device, an access point, a transceiver, a router, a switch, communication equipment, a computer network device, a stack of multiple computer network devices, a controller, test equipment, an Internet-of-Things (IoT) device, and/or another electronic device.

Although specific components are used to describe electronic device <NUM>, in alternative embodiments, different components and/or subsystems may be present in electronic device <NUM>. For example, electronic device <NUM> may include one or more additional processing subsystems, memory subsystems, networking subsystems, and/or display subsystems. Additionally, one or more of the subsystems may not be present in electronic device <NUM>. Moreover, in some embodiments, electronic device <NUM> may include one or more additional subsystems that are not shown in <FIG>. Also, although separate subsystems are shown in <FIG>, in some embodiments some or all of a given subsystem or component can be integrated into one or more of the other subsystems or component(s) in electronic device <NUM>. For example, in some embodiments program instructions <NUM> are included in operating system <NUM> and/or control logic <NUM> is included in interface circuit <NUM>. In some embodiments, the communication techniques are implemented using information in L1, L1. <NUM> and/or L2 of an Open Systems Interconnection (OSI) model.

Moreover, the circuits and components in electronic device <NUM> may be implemented using any combination of analog and/or digital circuitry, including: bipolar, PMOS and/or NMOS gates or transistors. Furthermore, signals in these embodiments may include digital signals that have approximately discrete values and/or analog signals that have continuous values. Additionally, components and circuits may be single-ended or differential, and power supplies may be unipolar or bipolar.

An integrated circuit (which is sometimes referred to as a 'communication circuit') may implement some or all of the functionality of electronic device <NUM> and/or networking subsystem <NUM>. The integrated circuit may include hardware and/or software mechanisms that are used for transmitting wireless signals from electronic device <NUM> and receiving signals at electronic device <NUM> from other electronic devices. Aside from the mechanisms herein described, radios are generally known in the art and hence are not described in detail. In general, networking subsystem <NUM> and/or the integrated circuit can include any number of radios. Note that the radios in multiple-radio embodiments function in a similar way to the described single-radio embodiments.

In some embodiments, networking subsystem <NUM> and/or the integrated circuit include a configuration mechanism (such as one or more hardware and/or software mechanisms) that configures the radio(s) to transmit and/or receive on a given communication channel (e.g., a given carrier frequency). For example, in some embodiments, the configuration mechanism can be used to switch the radio from monitoring and/or transmitting on a given communication channel to monitoring and/or transmitting on a different communication channel. (Note that 'monitoring' as used herein comprises receiving signals from other electronic devices and possibly performing one or more processing operations on the received signals).

In some embodiments, an output of a process for designing the integrated circuit, or a portion of the integrated circuit, which includes one or more of the circuits described herein may be a computer-readable medium such as, for example, a magnetic tape or an optical or magnetic disk. The computer-readable medium may be encoded with data structures or other information describing circuitry that may be physically instantiated as the integrated circuit or the portion of the integrated circuit. Although various formats may be used for such encoding, these data structures are commonly written in: Caltech Intermediate Format (CIF), Calma GDS II Stream Format (GDSII), Electronic Design Interchange Format (EDIF), OpenAccess (OA), or Open Artwork System Interchange Standard (OASIS). Those of skill in the art of integrated circuit design can develop such data structures from schematics of the type detailed above and the corresponding descriptions and encode the data structures on the computer-readable medium. Those of skill in the art of integrated circuit fabrication can use such encoded data to fabricate integrated circuits that include one or more of the circuits described herein.

While the preceding discussion used Ethernet and a Wi-Fi communication protocol as an illustrative example, in other embodiments a wide variety of communication protocols and, more generally, wired and/or wireless communication techniques may be used. Thus, the communication techniques may be used with a variety of network interfaces. Furthermore, while some of the operations in the preceding embodiments were implemented in hardware or software, in general the operations in the preceding embodiments can be implemented in a wide variety of configurations and architectures. Therefore, some or all of the operations in the preceding embodiments may be performed in hardware, in software or both. For example, at least some of the operations in the communication techniques may be implemented using program instructions <NUM>, operating system <NUM> (such as a driver for interface circuit <NUM>) or in firmware in interface circuit <NUM>. Alternatively or additionally, at least some of the operations in the communication techniques may be implemented in a physical layer, such as hardware in interface circuit <NUM>.

In the preceding description, we refer to 'some embodiments. ' Note that 'some embodiments' describes a subset of all of the possible embodiments, but does not always specify the same subset of embodiments. Moreover, note that numerical values in the preceding embodiments are illustrative examples of some embodiments. In other embodiments of the communication techniques, different numerical values may be used.

Claim 1:
A computer network device (<NUM>-<NUM>), comprising:
an interface circuit (<NUM>);
a processor (<NUM>); and
memory (<NUM>) configured to store program instructions (<NUM>), wherein, when executed by the processor, the program instructions cause the computer network device to perform operations comprising:
receiving (<NUM>) a report message (<NUM>) that is associated with a host (<NUM>-<NUM>), which indicates that the host wants to join a group in a network that receives an audio-video channel from a source (<NUM>);
adding (<NUM>), based at least in part on the report message, information (<NUM>) associated with the host to a group data structure (<NUM>) that comprises information associated with one or more hosts in the group;
when the computer network device receives (<NUM>) a leave message (<NUM>) that is associated with the host, removing (<NUM>, <NUM>) or deactivating, , based at least in part on information (<NUM>) corresponding to the leave message, the host from the group data structure; and
when the group data structure is empty (<NUM>) or has no active hosts, stopping forwarding (<NUM>, <NUM>) of the audio-video channel from the source to the group without further delay.