The Cisco IOS software supports dispatch sequences and TCP state machines that send data packets only when they receive a
defined character or sequence of characters. You can configure dispatch characters that allow packets to be buffered, then
sent upon receipt of a character. You can configure a state machine that allows packets to be buffered, then sent upon receipt
of a sequence of characters. This feature enables packet transmission when the user presses a function key, which is typically
defined as a sequence of characters, such as Esc I C.
TCP state machines can control TCP processes with a set of predefined character sequences. The current state of the device
determines what happens next, given an expected character sequence. The state-machine commands configure the server to search
for and recognize a particular sequence of characters, then cycle through a set of states. The user defines these states--up
to eight states can be defined. (Think of each state as a task that the server performs based on the assigned configuration
commands and the type of character sequences received.)
The Cisco IOS software supports user-specified state machines for determining whether data from an asynchronous port should
be sent to the network. This functionality extends the concept of the dispatch character and allows the equivalent of multicharacter
Up to eight states can be configured for the state machine. Data packets are buffered until the appropriate character or sequence
triggers the transmission. Delay and timer metrics allow for more efficient use of system resources. Characters defined in
the TCP state machine take precedence over those defined for a dispatch character.