You could still use the Array::Iterator::BiDirectional idea, populating the array iterator with the KEY of the hash.

However, if all instances of a route have already been loaded into memory (which, to me, is a lot of unnecessary overhead), You simply need to step through each one, comparing it to the previous one. (No need for the NEXT).

If you show us your code for the data structure you created, identifying the field names for the network, and path identifier, and instance, we could show you how to walk that structure.

Without that, abstract discussion will only confuse.