A method for processing link state information performed by a first network device, the method comprising the steps of: • receiving (S 601) first link state information from a second network device, wherein the first link state information carries information for computing a route to a third network device, the route being a route from the first network device to the third network device via the second network device, the first, second, and third network devices being different network devices; • determining (S 602), based on the first link state information, whether the first network device stores second link state information received from the second network device, wherein the second link state information carries a segment identifier of the third network device: ∘ when determining that the first network device stores the second link state information, updating (S 603) a route from the first network device to the third network device based on the first link state information, o when determining that the first network device does not store the second link state information, starting a timer, and determining, during timing of the timer, whether the first network device receives the second link state information from the second network device: ▪ when determining that the first network device receives the second link state information before the timer expires, updating (S 603) the route from the first network device to the third network device based on the first link state information, and ▪ when determining that the first network device does not receive the second link state information even after the timer expires, skipping updating the route from the first network device to the third network device based on the first link state information. • receiving (S 601) first link state information from a second network device, wherein the first link state information carries information for computing a route to a third network device, the route being a route from the first network device to the third network device via the second network device, the first, second, and third network devices being different network devices; • determining (S 602), based on the first link state information, whether the first network device stores second link state information received from the second network device, wherein the second link state information carries a segment identifier of the third network device: ∘ when determining that the first network device stores the second link state information, updating (S 603) a route from the first network device to the third network device based on the first link state information, o when determining that the first network device does not store the second link state information, starting a timer, and determining, during timing of the timer, whether the first network device receives the second link state information from the second network device: ▪ when determining that the first network device receives the second link state information before the timer expires, updating (S 603) the route from the first network device to the third network device based on the first link state information, and ▪ when determining that the first network device does not receive the second link state information even after the timer expires, skipping updating the route from the first network device to the third network device based on the first link state information. ∘ when determining that the first network device stores the second link state information, updating (S 603) a route from the first network device to the third network device based on the first link state information, o when determining that the first network device does not store the second link state information, starting a timer, and determining, during timing of the timer, whether the first network device receives the second link state information from the second network device: ▪ when determining that the first network device receives the second link state information before the timer expires, updating (S 603) the route from the first network device to the third network device based on the first link state information, and ▪ when determining that the first network device does not receive the second link state information even after the timer expires, skipping updating the route from the first network device to the third network device based on the first link state information. ▪ when determining that the first network device receives the second link state information before the timer expires, updating (S 603) the route from the first network device to the third network device based on the first link state information, and ▪ when determining that the first network device does not receive the second link state information even after the timer expires, skipping updating the route from the first network device to the third network device based on the first link state information.