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I am posting this article to ask question about history of multicast communication in iPhone. In multicasst communication, there is a comumunication protrocal called "IGMP". The protocol is divided into several different types such as "V2" and "V3".Recently, I encountered the problem which will not allow to obtain the information of communication function of app and it occured due to the by the difference in the types of communication protocol, .I am wondering if there is anyone who can answer or assist me with the following questions regarding communication history;a)When did iPhone start to correspond with multicast communication?b)Details of history of the model corresponded with the communication protocol, "V2" and "V3". (eg. when it started to correspond.)c)What was the trigger of enhancement and update for IGM communication function?Any assistance and information regarding this matter will be greatly appreciated.Thank you.