Explains MPLS LDP-IGP synchronization scenarios involving LDP graceful restart, covering how traffic is protected during LDP failures, synchronization maintenance during restart, and conditions under which IGP synchronization may be lost.
MPLS LDP-IGP synchronization is a protocol interaction that
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leverages LDP graceful restart to protect MPLS traffic when an LDP session fails
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maintains MPLS LDP IS-IS synchronization on the interface during the graceful restart protection window, and
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loses IGP synchronization if LDP fails to restart within the defined timer intervals.
LDP graceful restart protects traffic when an LDP session is lost. If an LDP session with graceful restart enabled fails, MPLS LDP IS-IS synchronization is maintained on the protected interface while graceful restart is active. MPLS LDP IGP synchronization is eventually lost in these circumstances:
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LDP fails to restart before the LDP graceful restart reconnect timer expires.
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The LDP session on the protected interface fails to recover before the LDP graceful restart recovery timer expires.