ASE/CE requires, at a minimum, ASE 15.x. Newer versions would be recommended due to bugs in the earlier releases.
For AIX 7.1 you're looking at a minimum of ASE 15.5. (http://certification.sybase.com/ucr/platformDetail.do?certId=3459&platformId=7&productId=2)
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While I've 'played' with CE in a 2-node environment that was a small proof of concept (that the client ended up passing on).
While it's technically possible to run a multi-node ASE/CE configuration, the (much) harder part is going to be figuring out how to partition your application(s) to work in a multi-node environment (eg, you don't want processes on 2 different nodes trying to update the same chunk of data => the overhead of the internode lock manager will likely introduce an unacceptable degradation in performance).