Same day settlement on international transfers through correspondent banking will be feasible if banks agree and follow a new set of business rules outlined by SWIFT at the end of last week.If the banks cooperate, fast and reliable cross border payments for trade will be a reality as soon as 2016. Billed as "new standard in cross-border payments," SWIFT's move is the embodiment of the collaborative effort in international banking, one made all the more interesting by the vigour of the challenge to which the industry is responding.Blockchain hero Ripple has more or less singled out correspondent banking as its killer app, with a greatly shortened payments delay central to the experience it has in mind.'Not so fast and no so easy' is the response of SWIFT, an outfit that might be considered more a cartel than a cooperative.Ripple and followers may yet find a niche among the world's many banks and industry challengers.But penetrating the core of the industry will be thorny as incumbents play one of their strongest hands.The compliance overlay SWIFT applies to its payments messaging business is one most banks rely on. Replicating, simplifying and lowering the cost of the circus that attends payments transfers is a legitimate target for a transformative offer from an outfit such as Ripple.Sadly the repeal of practically all the rules on know your customer and anti-money laundering and - yes, one more, the politics made it fashionable - counter-terrorism financing, is on no one's agenda but Banking Day's.For Ripple and others the hurdle is the degree of cooperation required among banks to make global banking harmonious.Of greatest interest is the warmth evident in an industry project coordinated, in part, at Sibos in Singapore in September.The world's banks may be responding to a customer need.But above all they may be conspiring to suppress the blockchain challenge.Fertile ground for excitable lawyers and Silicon Valley stories with Wall Street funding.