A network node 200 has a graceful restart (GR) mode in which it sends a GR notification to one or more neighbouring nodes 310-330, such as when a secondary control plane part (CCP) 220 becomes active due to failure of the primary CCP 210. The node attempts to re-establish an adjacency with its neighbours and receives link state data from at least one. From this information the node derives pre-restart link data and identifies links that were active prior to the restart. The node then detects which formerly active links are currently inactive, e.g. link 150 between interfaces 231 & 311, and continues with the GR. The node determines which of the formerly active links are currently active, e.g. links 150 between interfaces 232 & 321 and between 233 & 331, and exits the GR mode in response to successful re-establishment of adjacencies with neighbouring nodes for each of the currently active links. The advantage of the invention is that the GR procedure may be continued even if a topology change has been detected and thus the GR period is exited earlier than would otherwise occur and less volume of traffic may be lost.
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