Please help with this Computer Networks question, thank you
Please help with this
This service abstraction is carried out by a secure data transmission protocol.
The fact that the layer under the secure protocol of data transmission may not be reliable makes this job challenging. TCP, for example, is a trustworthy data transfer protocol applied on an untrustworthy end-of-the-network layer.
More commonly a single physical connection could be part of the layer below the two securely communicating endpoints, e.g. in the case of a link-level data transmission protocol or, as with the transportation level protocol, a global Internet connection.
But we can see this lower layer clearly as a point-to-point insecure channel for our purposes.
But how long does the sender have to wait to make sure anything is lost
It obviously needs to wait at least as long as the sender and receiver have a round trip time (which may require buffering on intermediate routers or gateways), plus any time required for transmitting the packet on the receiver.
This maximum delay is very difficult to even predict in many networks, far less surely understood.
In addition, it is preferably acceptable that the protocol recovers from packet failure as quickly as possible
It may entail waiting until the worst time possible before errors have been recovered. The solution thus taken in practice is that senders pick a time value "judiciously',' which would certainly cause packet loss, but not guaranteed.
The packet would be sent if an ACK is not received in that moment. Please remember, if a packet is especially overdue, the sender will forward the packet even though the data packet is not one.
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