TCP Keepalive
Under Transmission Control Protocol (TCP) keepalives are an optional feature, and if included must default to off. The keepalive packet contains null data. In an Ethernet network, a keepalive frame length is 60 bytes, while acknowledge to this, also a null data frame, is 54 bytes. There are three parameters related to keepalive:
- Keepalive time is the duration between two keepalive transmissions in idle condition. TCP keepalive period is required to be configurable and by default is set to no less than 2 hours.
- Keepalive interval is the duration between two successive keepalive retransmissions, if acknowledgement to the previous keepalive transmission is not received.
- Keepalive retry is the number of retransmissions to be carried out before declaring that remote end is not available.
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