
Frame Relay Overview
117376-C Rev. 00
2-11
The supervisory frames, RNR and RR, support flow control on the channel. If the
receiver is not ready to receive data, it sends an RNR message to tell the sender to
wait. When it is ready to receive data, it sends an RR message. Flow control in one
direction is independent of the other direction.
Timer T203
Timer T203 is used to detect a lost connection. When either end of the link is not
waiting for any data, it starts timer T203. If it sends or receives no frames before
this timer expires, the peer transitions to the timer recovery state, sends either an
RR or RNR message to the remote peer, and starts timer T200. If timer T200
expires, the connection is assumed lost, and the peer transitions to the
TEI-assigned state.
To terminate multiple frame support on the circuit, one peer sends a DISC
message to the other. The receiving peer responds with a UA message, and
disconnects the circuit.
SVC Signaling
The following sections describe the signaling between a DTE and the frame relay
network in which various types of messages are exchanged.
Table 2-3
contains a list of timers used in the signaling exchanges that occur. You
can use Site Manager to configure these timers to your specific requirements.
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