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unnumbered acknowledgement (HDLC) (UA)

The Unnumbered Acknowledgement(UA), the acknowledgement without sequence number, is used in the HDLC protocol to confirm that a connection has been established on the link layer and that the transmission is in spontaneous mode.

The UA message is used to confirm and accept U commands, such as Set Asynchronous Balanced Mode( SABM) and Disconnect( DISC). These commands basically execute a change to a different state than the previous one, from Asynchronous Balanced Mode( ABM) to Asynchronous Disconnect Mode( ADM) or vice versa.

Englisch: unnumbered acknowledgement (HDLC) - UA
Updated at: 17.11.2012
#Words: 82
Links: user agent (UA), sequence number (SEQ), high level data link control (HDLC), protocol, connection
Translations: DE

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