An LSR sets up a Hello adjacency with another LSR by exchanging Hello messages with the other LSR. The LSR starts a Hello Hold timer to maintain the Hello adjacency. When receiving a Hello message of the Hello adjacency, the LSR resets the Hello Hold timer. If the Hello Hold timer expires, the LSR deletes the Hello adjacency. In addition, if an LDP session is set up only through this Hello adjacency, the LDP session is deleted.

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