That is the anthem of the Republic of Ireland/EIRE/Free state. Irelands Call was written to be an inclusive anthem which recognises the presence of players from NI. Soldier song is only played at home games; away games gets the Ireland Call treatment.
The official "anthem" of the Irish rugby team is "Ireland's Call" as stated, it is an inclusive anthem due to the fact that the team comprises players from both parts of the island.
The Eire anthem "The Soldiers Song" is only played at home games when the President is in attendance, its a protocol issue, nowt to do with rugby.