A communication apparatus (1A, 1B, 1C) configured to control a bandwidth of communication when a transmitting apparatus and a receiving apparatus perform communication via a network, comprising: a measuring unit configured to measure the bandwidth for communication of at least one direction of two directions, a first direction from the transmitting apparatus to the receiving apparatus and a second direction from the receiving apparatus to the transmitting apparatus, the measuring of bandwidth by observing at said communication apparatus (i) for said first direction an accumulated data length of a series of first packets sent from the transmitting apparatus obtained by observing a first number included in each first data packet and a data length of each first data packet within a predetermined period, and/or (ii) for said second direction counting the increment of a second number indicated by a series of second packets within a predetermined period, each second packet sent by the receiving apparatus back to the transmitting apparatus to confirm receipt of a corresponding first packet; a storing unit configured to store information regarding bandwidth adjustment including a target bandwidth indicating a bandwidth required for communication associated with information identifying the session between the transmitting apparatus and the receiving apparatus; an adjusting unit configured to read out, from the storing unit, the target bandwidth of the direction for which the bandwidth was measured, and based on a comparison of the bandwidth measured at the measuring unit and the read out target bandwidth, to perform throttling or enhancing of the bandwidth by controlling the transmission interval of said first packets so that an increment of said first number per unit time is within a predetermined range, and/or by controlling the transmission interval of said second packets so that an increment of said second number per unit time is within a predetermined range, when relaying or transmitting the first and/or second packets from said communication apparatus (1A, 1B, 1C), and optionally said enhancing of the bandwidth by controlling the transmission interval of at least one duplicate first and/or second packet. a measuring unit configured to measure the bandwidth for communication of at least one direction of two directions, a first direction from the transmitting apparatus to the receiving apparatus and a second direction from the receiving apparatus to the transmitting apparatus, the measuring of bandwidth by observing at said communication apparatus (i) for said first direction an accumulated data length of a series of first packets sent from the transmitting apparatus obtained by observing a first number included in each first data packet and a data length of each first data packet within a predetermined period, and/or (ii) for said second direction counting the increment of a second number indicated by a series of second packets within a predetermined period, each second packet sent by the receiving apparatus back to the transmitting apparatus to confirm receipt of a corresponding first packet; a storing unit configured to store information regarding bandwidth adjustment including a target bandwidth indicating a bandwidth required for communication associated with information identifying the session between the transmitting apparatus and the receiving apparatus; an adjusting unit configured to read out, from the storing unit, the target bandwidth of the direction for which the bandwidth was measured, and based on a comparison of the bandwidth measured at the measuring unit and the read out target bandwidth, to perform throttling or enhancing of the bandwidth by controlling the transmission interval of said first packets so that an increment of said first number per unit time is within a predetermined range, and/or by controlling the transmission interval of said second packets so that an increment of said second number per unit time is within a predetermined range, when relaying or transmitting the first and/or second packets from said communication apparatus (1A, 1B, 1C), and optionally said enhancing of the bandwidth by controlling the transmission interval of at least one duplicate first and/or second packet.