Garryowen edged past a rejuvenated Shannon at Dooradoyle in a game that did not live up to expectations.
Garryowen will be relieved to maintain their great start to the campaign, while Shannon picked up their first point of the season, albeit a losing bonus one.
Out-half Jamie Gavin landed Garryowen's first penalty in the eighth minute, but it was all square after 27 minutes when Rob Guerin was on target for Shannon.
After a poor first half, a big improvement was expected after the break, but it was a battle of the kickers throughout.
Gavin kicked four penalties for Garryowen, his last strike coming 11 minutes from time. That left it 12-6 after Guerin had landed his second Shannon penalty.
Shannon needed a try to snatch victory, but they couldn't find one.
Garryowen -- R O'Mahony; J McInerney, C O'Shea, C Doyle, E Connolly; J Gavin, N Cronin; R Brosnan, J Rael, JP Cooney; A Kennedy, A McCloskey; S Buckley, A Kavanagh, D Sherry. Reps: D Rowley, B Cullinane, M Hanrahan, C hartigan, G Ryan.
Shannon -- L O'Dea; R Mullane, E Moloney, E O'Connor, C O'Donnell; R Guerin, M Darcy; N Horan, D Casey, G McNamara; F Walshe, S McCarthy; J Murphy, J Shine, M Essex. Reps: J Cronin, K Griffin, J Gleeson, M Culhane, M Leonard.
Ref -- P Haycock (IRFU).