If GETBULK returns less (no) variable bindings than you expect it to return then check

• the maxRepetitions parameter of the GETBULK request PDU
• the maxSizeRequestPDU parameter of the Target
• whether the agent has local limits (i.e., memory) that do not allow to return a bigger GETBULK response PDU. In that case, the GETBULK response will contain less variable bindings than

  nonRepeaters + maxRepetitions * repeaters

  .
• whether the expected response PDU exceeds the MTU size of the used UDP network. In that case, the request will time out because UDP packets are usually not reassambled.