However, the aforementioned notification mechanisms are utilized in {HEAD ~ yet other embodiments} to confirm the existence of a fully functional bi directional path using only a test request and a test reply—or via {TAIL ~ separate tests} initiated by issuing a test request from each redundant network access point of a node  
However , the aforementioned notification mechanisms are utilized in { HEAD ~ yet other embodiments } to confirm the existence of a fully functional bi directional path using only a test request and a test reply — or via { TAIL ~ separate tests } initiated by issuing a test request from each redundant network access point of a node
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