The document discusses transfer reliability and congestion control strategies in opportunistic networks. It begins by stating that opportunistic networks have unpredictable node contacts and rarely have complete end-to-end paths. It then discusses how modified TCP protocols are ineffective for these networks and they require different approaches than intermittently connected networks. The document surveys proposals for transfer reliability using hop-by-hop custody transfer and end-to-end receipts. It also categorizes storage congestion control based on single or multiple message copies. It identifies open research issues including replication management and drop policies for multiple copies.