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to create an LFIB entry for that FEC. When all LSRs (from the Ingress to the Egress) establish an
LFIB entry for the FEC, an LSP is established exclusively for the FEC.
Figure 9 Dynamically establishing an LSP
149BLabel distribution and control
332BLabel advertisement modes
LDP advertises label-FEC mappings in one of the following ways:
• Downstream Unsolicited (DU) mode—Distributes FEC-label mappings to the upstream LSR,
without waiting for label requests. The device supports only the DU mode.
• Downstream on Demand (DoD) mode—Sends a label request for an FEC to the downstream
LSR. After receiving the label request, the downstream LSR distributes the FEC-label mapping
for that FEC to the upstream LSR.
Figure 10 Label advertisement modes
NOTE:
To successfully establish an LSP, a pair of upstream and downstream LSRs must use the same
label advertisement mode.
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