Hayes received a red card under law 10.4 (b) for a stamp on Leinster prop Cian Healy in the 54th minute of the game.
The hearing took place in the Ulster Branch offices in Ravenhill, Belfast at 4pm. The IRFU panel consisted of Hugh Logan (Chairman), Stephen Hilditch and Neil Jackson.
Having studied the match footage and heard all available evidence, the disciplinary panel confirmed that the offence constituted a high end entry level in terms of sanctions.
Having also considered all mitigating factors, the panel imposed a six week suspension from the date of the offence on Saturday, October 3 up to and including Saturday, November 14.
The ban means Hayes will miss Munster's next four matches, including their opening Heineken Cup fixtures against Northampton Saints and Benetton Treviso.
He will, however, be able available for Ireland's GUINNESS Series 2009 ties against Australia, Fiji and World and Tri Nations champions South Africa.
The player has the right to appeal this decision.
In a statement released after the hearing, Munster team manager Shaun Payne said: "John regrets the incident happened at all. He has a long and unblemished professional rugby career spanning twelve seasons and would not be regarded by anybody including opponents as being a dirty player.
"He is very disappointed with the sanction, given that the committee accepted the action wasn't intentional yet decided the entry point for the offence to be at the higher range, the nine weeks reduced to six in mitigation."