Method and device for transmitting multicast messages

Abstract

The invention provides a method and device for transmitting multicast messages, and is applied to NAT (Network Address Transform) equipment. The method comprises the following steps of: A. receiving messages from each side interface of a private network of the NAT equipment, and identifying the multicast messages according to the destination addresses of the messages and going to a step B; B. receiving the static mapping relationship between an IP (Internet Protocol) address of the private network and an IP address of a public network issued by an administrator and storing in a static mapping relationship table; and C. according to a source IP address carried by the multicast messages, finding the static mapping relationship table, if finding a corresponding public IP address, then converting the source IP address of the multicast messages into the IP address of the public network and then sending out from an interface of the public network, otherwise discarding the multicast messages. According to the method and the device provided by the invention , the processing characteristics of the NAT equipment for the messages are fully considered, although the configuration is needed, the transformation of the equipment is very small, the overall implementation is simple, and the cost for transformation of the network is extremely low.

Description

technical field [0001] The invention relates to multicast technology, in particular to a method and device for transmitting multicast messages through NAT. Background technique [0002] With the rapid increase of the number of computers connected to the Internet, IPv4 address resources appear to be stretched. In fact, except for China Education and Research Network (CERNET), general users can hardly apply for the entire segment of C-class IP addresses. In other ISPs, even for large LAN users with hundreds of computers, when they apply for IP addresses, the addresses allocated are only a few or a dozen IP addresses. Obviously, such a small number of IP addresses cannot meet the needs of network users at all. With the help of NAT technology, when a private IP address sends a message through a router, the private IP address will be converted into a "legal" public IP address, so a LAN network only needs to use a small number of IP addresses (even one) to achieve All computers...

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Problems solved by technology

[0004] However, the implementation of such a solution requires three conditions. First, the NAT device supports the MSDP protocol. Second, the router on the NAT private network side must also support the MSDP protocol. Third, the router on the NAT private network side must also support the MSDP protocol. Run the PIM-SIM protocol; however, many users' networks cannot meet the above three conditions at the same time, and users must carry out large-scale transformation of the network to meet the above three conditions, or they can only suffer from the problem that multicast packets cannot pass through the NAT device

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