A system for transmitting packets over a network of communication channels, the system comprising: a first node connectable to a second node and a network access coordinator via a coax backbone, the network access coordinator for coordinating access of the first and second nodes to the coax backbone, said first node comprising a retransmission buffer, wherein each of said packets comprises a sequence number, SN, wherein the lowest sequence number of a packet that still exists in the retransmission buffer is referred to as a start sequence number, SSN; wherein said first node is adapted to transmit a reservation request to the network access coordinator prior to a first time period in which at least one first packet is transmitted by the first node to the second node, said reservation request comprising: an indication that retransmission service is applied; and a length corresponding to the at least one first packet; and wherein, if, during the first time period the at least one first packet is not received by the second node: the first node is operative to receive from the network access coordinator an indication that the network access coordinator received a retransmission request; the first node is operative to retransmit the at least one first packet and all subsequent transmitted packets; and the first node is operative to: check if a SN value of a new transmitted packet is larger than the SSN value by a pre-determined threshold, and if so: increment the SSN value accordingly; and remove from the retransmission buffer all packets having SN values lower than the incremented SSN value. a first node connectable to a second node and a network access coordinator via a coax backbone, the network access coordinator for coordinating access of the first and second nodes to the coax backbone, said first node comprising a retransmission buffer, wherein each of said packets comprises a sequence number, SN, wherein the lowest sequence number of a packet that still exists in the retransmission buffer is referred to as a start sequence number, SSN; wherein said first node is adapted to transmit a reservation request to the network access coordinator prior to a first time period in which at least one first packet is transmitted by the first node to the second node, said reservation request comprising: an indication that retransmission service is applied; and a length corresponding to the at least one first packet; and an indication that retransmission service is applied; and a length corresponding to the at least one first packet; and wherein, if, during the first time period the at least one first packet is not received by the second node: the first node is operative to receive from the network access coordinator an indication that the network access coordinator received a retransmission request; the first node is operative to retransmit the at least one first packet and all subsequent transmitted packets; and the first node is operative to: check if a SN value of a new transmitted packet is larger than the SSN value by a pre-determined threshold, and if so: increment the SSN value accordingly; and remove from the retransmission buffer all packets having SN values lower than the incremented SSN value. the first node is operative to receive from the network access coordinator an indication that the network access coordinator received a retransmission request; the first node is operative to retransmit the at least one first packet and all subsequent transmitted packets; and the first node is operative to: check if a SN value of a new transmitted packet is larger than the SSN value by a pre-determined threshold, and if so: increment the SSN value accordingly; and remove from the retransmission buffer all packets having SN values lower than the incremented SSN value. check if a SN value of a new transmitted packet is larger than the SSN value by a pre-determined threshold, and if so: increment the SSN value accordingly; and remove from the retransmission buffer all packets having SN values lower than the incremented SSN value. increment the SSN value accordingly; and remove from the retransmission buffer all packets having SN values lower than the incremented SSN value.