Error correction techniques for IP networks (Part 2 – ARQ)

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ARQ Characteristics

ARQ technology monitors whether or not the receiver obtains all IP packets. If a packet is not obtained after a certain amount of time elapses, the receiver will transmit a retransmission request to the transmitter to resend the lost packet. If more packets are lost, more retransmission requests are sent.

Details of ARQ are as follows:

1. In practice, the ARQ bandwidth must be capped on a network with limited bandwidth. Theoretically, the ARQ could disrupt the transmission by transmitting too much data, causing newer packets to drop due to limited bandwidth, thus creating a snowball effect.
2. ARQ needs time to make sure a packet is lost rather than simply out of order. This means that the receiver must buffer the data while the ARQ determines whether a packet is lost and request the lost IP packet from the transmitter. This will increase the overall transmission latency significantly (multiple times the original transmission delay).
3. ARQ requires a two way transmission link to work.
4. ARQ does not support multi-cast transmission. It only works on a point-to-point connection.
5. ARQ often has problems passing through “Firewalls”.
6. ARQ requires little to no overhead if no transmission errors are detected.

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