Mapping of a source specific multicast group address to a source address

Mapping of the first source multicast group address to the source address TECHNICAL FIELD The present invention generally relates to the Internet protocol, and more specifically, to the host reservation management protocol.

BACKGROUND Internet Protocol (IP) communication generally provides three different types of host communication methods on a network, namely, unicast, broadcast, and multicast. Unicast is a point-to-point communication method, most commonly used when two hosts need to exchange data with each other and do not involve sharing data with multiple hosts. Broadcast is to reach all hosts in the broadcast domain, while multicast allows a group of hosts to receive messages without broadcasting these messages to all hosts in the broadcast domain.

Multicast overview For many common network broadcast applications, multicast is usually a preferred communication method. This is because multicast is a bandwidth-saving technology that reduces traffic by delivering data to multiple hosts at the same time. An example of an application that uses multicast is a video conferencing application. Those hosts that wish to receive video can join a group that has a multicast group IP address. Once the receiver has joined the multicast group, the server responsible for sending the video only needs to send the video to the IP address of the multicast group (as opposed to the following two cases, one is to send the video exclusively to each host (unicast), The other is to send video (broadcast) to all hosts on the network. Other applications that use multicast include corporate communications, distance education, and the dissemination of software, stock quotes, and news.

Multicast delivers data to multiple receivers without burdening the source host. This is because multicast packets are replicated in the network by a multicast-enabled router (a multicast-enabled router is a router that is configured to support multicast) at the point of path bifurcation. In contrast, many alternative techniques for multicast require the source to send more than one copy of the data.

03818291.2 Multicast group Multicast is based on the concept of group. A multicast group is any group of receivers that intend to receive a specific data stream from the source. Hosts that want to receive data sent to a multicast group must use the Internet Group Management Protocol (IGMP) (discussed below) to join the group. Only those hosts that are members of a given multicast group can receive data sent to this multicast group.

Internet Group Management Protocol (IGMP)

IGMP is a protocol used by hosts and multicast-enabled routers to form and manage multicast groups. To join a group, the host sends an IGMP membership report to the local multicast router. The membership report indicates to the local multicast router that the host intends to join a particular multicast group. The address of the multicast group is included in the membership report. The router recognizes that the host wants to join the group, so it establishes a path from the source to the host, and then uses it to forward data to the host.

There are multiple versions of IGMP, that is, there are multiple versions of membership reports. IGMP version 1 (IGMPvl) and IGMP version 2 (IGMPv2) membership reports allow a host to include a group address that is used to identify the group to which the host wishes to join. IGMP version 3 (IGMPv3) allows a host to identify not only the group that the host wants to join, but also the source from which the host expects data to be sent, thereby extending the capabilities of IGMPvl and IGMPv2.

Fixed-source multicast (Source Speci c Multicast, SSM) There may be multiple sources transmitting data to a single multicast group. For example, one source can transmit stock quotes to a multicast group, while another source can transmit video conference information to the same multicast group. A host that has joined the multicast group to receive stock quotes may also unwillingly receive video conference data. In order to alleviate this potential burden, fixed-source multicast (SSM) extends the existing multicast protocol by providing a "source filtering" function in the multicast network. With the source filtering function, when a host joins a specific multicast group, the host can not only specify the multicast group that the host wants to join, but also specify the source from which it wants to send data to the multicast group. The source filtering function allows the host to filter out unwanted or even malicious data streams sent from unknown sources to the multicast group.

SSM implements the source filtering function through channels, which can be considered as group extensions. The channel is identified by the SSM group address (G) and source address (S). Source to SSM group address (G) transmission

03818291.2 The first data sent. The host can receive data only by subscribing to the channel (S, G) (pronounced "S comma G"). Because of Jit, before the host can subscribe to the channel, the host preferably needs to know the SSM group address (G) and source address (S). The ability to specify the SSM channel address is provided in the IGMPv3 membership report (As mentioned in the previous section, the IGMPv3 report allows the host to provide the group address and source address).

However, many hosts are not configured with IGMPv3 and/or lack the ability to send IGMPv3 membership reports. Although hosts configured with IGMPvl and IGMPv2 have the ability to specify group addresses in membership reports, these hosts lack the ability to specify source addresses. In addition, there may be a large number of hosts on the network that are not configured with IGMPv3, and there is a lack of effective upgrade methods, which means that these hosts cannot be configured with IGMPv3 for a period of time. This greatly limits the use of SSM. As a result, before the host became IGMPv3 compatible, many applications that were originally designed to run on the SSM network were useless. Therefore, there is a need for a system and method that can implement the SSM function in a network where one, some or all of the hosts lack the ability to reserve channels.

SUMMARY OF THE INVENTION According to a first aspect of the present invention, a method is provided, including: in response to directly or indirectly receiving a first membership report sent by a host, mapping a first address to a second address, wherein the The first membership report includes the first address, and the first membership report does not include the second address; generating a protocol-independent multicast join, wherein the protocol-independent multicast join includes the first address and The second address mapped to it.

According to a second aspect of the present invention, there is provided a multicast network device, including: a memory containing a first address; and a sourced multicast mapping engine, which is configured to respond to directly or indirectly receiving a message sent by a host Including a membership report of the first address, mapping the first address to a second address to generate a protocol-independent multicast join, wherein the protocol-independent multicast join includes the first address and the second address, And the membership report does not include the second address.

According to a third aspect of the present invention, there is provided a multicast network device, including: a memory containing a first address; and for mapping the first address to a second address, and for responding to

03818291.2 The first multicast network device directly or indirectly receives the membership report including the first address sent by the host to generate a protocol-independent multicast join device, wherein the protocol-independent multicast join includes the first An address and a second address, and the membership report does not include the second address.

The above is a summary of the content of the invention, and therefore contains simplifications, generalizations, and omissions of details when necessary; therefore, those skilled in the art will understand that this summary is only illustrative and not restrictive. of. It is also clear to those skilled in the art that the operations disclosed herein can be implemented in various ways, and various modifications and changes can be made without departing from this invention and its broader scope. In the non-limiting detailed description set forth below, other aspects of the present invention defined only by the claims will become clear.

03818291.2 Description of Figures The present invention can be better understood with reference to the accompanying drawings.

Figure 1 illustrates an exemplary network according to an embodiment of the present invention.

Figures 2a and 2b illustrate the actions involved in allowing the host to receive data transmitted on one or more channels according to the present invention.

FIG. 3 is a flowchart illustrating the actions generally performed by the SSM mapping engine in order to allow the host to receive data on the channel according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Introduction The embodiments of the present invention generally allow a host to subscribe to and receive data transmitted on a certain channel in a multicast network by preferably providing a single address. The following content sets forth a detailed description of the mode for implementing the present invention. These descriptions are only intended to illustrate the present invention schematically, and should not be regarded as restrictive.

Network Components FIG. 1 illustrates an exemplary network 100 according to an embodiment of the present invention. The network 100 includes a source 102 configured to transmit data on a channel 104 to a receiver 106. The network 100 is preferably an SSM enhanced network configured to support fixed source multicast (SSM) communication. The source 102 is preferably an SSM source. The SSM source used here refers to a host that is configured to transmit data to the SSM group address (G). The receiver 106 is preferably an SSM receiver. The SSM receiver used here refers to a host configured to receive data transmitted by the SSM source. Although it is preferable that the source 102 and the receiver 106 are an SSM source and an SSM receiver, respectively, the source 102 and the receiver 106 may also be any hosts capable of communicating on the network 100. The channel used here identifies the SSM data path (also called a tree) associated with the SSM source (S) and destination SSM group address (G). A channel is identified by a channel address (S, G) (read as "S comma G"), where S represents the address of the source configured to transmit data to the destination SSM group address represented by G on the channel.

03818291.2 The first receiver 106 is a member of the group 108 addressed according to the group address (G) 110. The group 108 is preferably an SSM group, and the group address 110 is preferably an SSM group address. However, the group 108 and the group address 110 may also be any group and group address that can realize multicast communication.

The network 100 also includes a communication path 112 and a multicast network device (MND) 114. Each communication path 112 may be a direct communication link, a local area network (LAN), a wide area network (WAN), an IP-based network (such as the Internet), or some combination thereof. Each MND may be, for example, a multicast router, or a similarly configured system capable of processing data on the network 100. The MND 114(e) includes a memory 116, an SSM mapping engine 118, an SSM mapping database 120, and a messaging engine 122. Although not required, one or more other MNDs 114 other than MND 114(e) may each include a memory 116, an SSM mapping engine 118, an SSM mapping database 120, and a messaging engine 122. In the described embodiment, the messaging engine 122 is an IGMP module, but the messaging engine 122 may also be any other messaging engine used in a multicast network that supports multicast. The host 124 and the system 126 including the database 128 are also connected to the network 100.

Network configuration and operation To help understand the invention, the described embodiments of the invention are given in the following context, in which a host membership report that preferably contains a single address is used to allow the host 124 to subscribe to one or more entries. A channel, such as channel 104(e). Used here, a host membership report refers to data transmitted by a host to indicate the host's desire to become a member of a multicast group. The description of the configuration of the network 100 is given only to provide a context in which the present invention can be more easily understood, and is not intended to be restrictive.

Source 102(a) is preferably configured to transmit data on channel 104(a). The channel 104(a) is represented by a channel address (Sa, G), which indicates that the source 102(a) is preferably configured to transmit data to the SSM group address 110 (represented by G). Similarly, the SSM source 102(b) is configured to transmit data on the channel 104(b). The channel 104(b) is represented by a channel address (Sb, G), which indicates that the source 102(b) is also configured to transmit data to the SSM group address 110. The receiver 106 is preferably configured to only receive data on channel 104(a), and therefore can filter out any data transmitted on channel 104(b).

03818291.2 Transmitting Membership Report Figures 2a and 2b illustrate the actions involved in allowing the host 124 to receive data transmitted on the channel 104(a) according to the present invention. Initially, in action 2, the host 124 transmits a host reservation protocol message 204 to the MND 114(e), the message including the first address 206. Preferably, in the described embodiment, the subscription protocol message 204 is an Internet Group Management Protocol version 1 (IGMPvl) or version 2 (IGMPv2) membership report, and the first address 206 is an SSM group address, such as SSM group address 110 , Which represents the component quantity of the channel that the host 124 wants to subscribe. In order to make the description clear, the SSM group address 206 will refer to the first address 206 hereinafter.

IGMP is a host reservation protocol used by a host (e.g., host 124) to report host group membership to an adjacent multicast router (e.g., MND 114(e)). In the embodiment where the subscription protocol message 204 is an IGMP membership report, the IGMP membership report is preferably performed by the TCP/IP (Transmission Control Protocol/Transmission Control Protocol) running on the host 124 when the application opens the multicast socket on the host 124 Internet Protocol) stack.

The mapping address is in action 4, the messaging engine 122 receives the subscription protocol message 204 in the memory 116, and provides the data contained therein (including the SSM group address 206) to the given source multicast (SSM) mapping engine 118. In the present invention In one embodiment, the MND 114(e) is a multicast router configured to execute computer-readable code, and the SSM mapping engine 118 is composed of multiple modules of computer-readable code, which are designed to allow the host 124 to do this The host receives data on a multicast channel (e.g., channel 104(a)).

In action 6, the SSM mapping engine 118 receives the SSM group address 206, and queries the static SSM mapping database 120 to obtain the second address 208 corresponding to the SSM group address 206. In the described embodiment, the second address 208 is preferably the address of a source (eg, SSM source 102(a)) that is configured to transfer data to a group address such as SSM group address 206. All corresponding SSM source addresses (if any) found for the SSM group address 206 are all returned to the SSM mapping engine 118 for caching and further processing as described below. For simplicity of description, the SSM source address 208 will be used to refer to the second address 208 hereinafter.

03818291.2 The mapping of the SSM group address 206 to the corresponding SSM source address 208 is preferably performed at the IGMP layer (ie, IGMP commands and protocols are used). The static SSM mapping should preferably be configured before querying the static SSM mapping database 120. In order to configure the static SSM mapping database 120, the static SSM mapping must be enabled, and the SSM mapping database 120 must be constructed. Preferably, in order to enable static SSM mapping, enter the command ip igmp ssm-map enable on MND 114(e). In order to establish the static SSM mapping database 120, preferably enter the command ip igmp ssm-map on MND 114(e) static <acl-x> <source-x IP address>. The <acl-x> parameter is used to specify the SSM group address that will be mapped to the <source-x IP address> parameter. For example, in the described implementation , Preferably enter the following command to establish a static SSM mapping database 120: ip igmp ssm-map static <group address> <source 1 address>

ip igmp ssm-map static <group address> <source 2 address>

It can be recognized that <group address> is the IP address of a certain group (for example, group 108), and <source 1 address> is the IP address of the first source (for example, source 102(a)) that will be mapped to the group, <source 2 address> is the IP address of the second source (eg source 102(b)) that will also be mapped to the group. This command can be repeated for any number of group addresses that will be mapped to the assigned source address.

In act 8, after querying the static SSM mapping database 120, the SSM mapping engine 118 queries the database 128 of the system 126. In the described embodiment, the system 126 is a DNS (Domain Name Server). If necessary, you can use the command: no ip igmp ssm-map query dns to prohibit database 128 queries. The domain server should preferably be configured on the MND 114(e) in order to query the database 128. This can be achieved with the following command: "ip domain-server <ip-address>ⁿ。

When constructing the database 128, in order to discover the source corresponding to a specific multicast group, it is preferable to use an A record to perform a reverse DNS lookup using the multicast group IP address. If the system 126 includes the corresponding source address of the group address, the system 126 will return the corresponding source address. Otherwise, the system 126 preferably forwards the query to a known root DNS server (not shown). In one embodiment of the present invention, the network administrator of the system 126 preferably determines the source address to group address mapping, and constructs the database 128 accordingly.

03818291.2 In action 10, the source address 208 corresponding to the SSM group address 206 is located in the database 128 and is returned to the SSM mapping engine 118. Preferably, the local configuration mapping obtained from the static SSM mapping database 120 is relative to that contained in the database 128 The dynamic mapping in occupies priority. In act 12, when received, the SSM mapping engine 118 preferably caches the source address 208, and generates the channel address 210 from the SSM group address 206 and the SSM source address 208. In some embodiments, a second membership report is also generated according to the channel address, wherein the second membership report is an IGMP version 3 membership report.

In action 14, the MND 114(e) initiates a protocol independent multicast (PIM) join 210 to the source 102(a), including the channel address of the channel 104(a). PIM is an independent routing protocol and can be used to construct the shortest communication path between an SSM source (e.g., source 102(a)) and an SSM receiver (e.g., receiver 106(a)). The PIM join message 210 preferably establishes a path between the host 124 and the source 102(a) that allows the host 124 to receive data transmitted by the source 102(a) on the channel 104(a).

FIG. 3 illustrates that according to the present invention, in order to allow a host (for example, the host 124) to receive data on a channel (for example, channel 104(a)), for example, using only IGMPvl or IGMPv2 membership reports, the SSM mapping engine 118 is generally executed Flow chart of the actions.

Initially, the messaging engine 122 receives the IGMP membership report in the memory 116 including the group address (eg, the group address 206) (step 302). The group address in the IGMP membership report identifies the group amount of the channel (for example, channel 104(a)) that the host 124 wishes to subscribe. After receiving the IGMP report, the SSM mapping engine 118 preferably performs some verification, as shown by the pseudo code in step 304. The SSM mapping engine 118 preferably verifies that the static SSM mapping is configured (as previously described with reference to FIG. 2), the IGMP report is a valid IGMPv1 or IGMPv2 report, and the group address included in the IGMP report is a valid SSM group address. If any of the above verifications fails, the SSM mapping engine 118 continues normal IGMP processing. However, if preferably all verifications are satisfied, the SSM mapping engine 118 queries the SSM static database (such as the SSM static database 120) and the domain name server (DNS) database (such as the database 128) to find the information provided in the IGMP report The source address corresponding to the SSM group address (step 308) ο

The SSM mapping engine 118 first queries the SSM static database. If a correspondence is found

03818291.2 first source address (for example, source address 208), then the source address is preferably cached, and a channel address (for example, channel address 210) is formed ("Yes" branch of decision block 310 and step 318).

03818291.2 First, however, if the corresponding source address is not found in the SSM static database, the SSM mapping engine 118 proceeds to query the DNS database ("No" branch of decision block 310).

Before querying the DNS database, the SSM mapping engine verifies that such a query has been enabled (decision box 312). If the query to the DNS database is not enabled and the corresponding source address is not found in the SSM static database, it is preferably ignored IGMP report ("Yes" branch of decision block 312 and step 314). However, if the query to the DNS database is enabled, the SSM mapping engine queries the DNS database to find the source address corresponding to the group address provided in the IGMP report ("No" branch of decision block 312 and decision block 316).

If the corresponding source address is not found in the DNS database, the IGMP report is preferably ignored (the "No" branch of decision block 316 and step 314). However, if the corresponding source address is found in the DNS database, then this corresponding The source address is returned to the SSM mapping engine 118, where the source address is cached and used to form the channel address (eg, channel address 210) ("Yes" branch of decision block 316 and step 318).

In step 320, the SSM mapping engine 118 initiates a protocol-independent multicast PIM (Sa, G) addition to the source address obtained from the SSM static database and/or the source obtained from the DNS database. In another embodiment of the present invention, the SSM mapping engine 118 initiates PIM (Sx, G) addition to one or more or all source addresses obtained from the SSM static database and/or DNS database (where Sx is the The address of the source to which the PIM join will be transmitted). Add host 124 to channel 104(a), which is also called subscribing host 124 to channel 104(a) ο PIM (Sa, G) is added to establish between host 124 and the source identified by the obtained source address Start a pathway. This path allows the host 124 to receive data transmitted by a source on the corresponding channel (eg, source 102(a) on channel 104(a)).

Although the specific embodiments of the present invention have been shown and described, it is obvious to those skilled in the art that, based on the teachings herein, a variety of methods can be made without departing from this invention and its broader scope. Changes and modifications, therefore, the appended claims intend to include within their scope those modifications and changes that fall within the true spirit and scope of the present invention. Furthermore, it is understood that the present invention is only limited by the appended claims.

Applicability The various embodiments of the present invention can be used in the field of networking.

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