  Two mobile agents, starting from different nodes of a network modeled as a
graph, and woken up at possibly different times, have to meet at the same node.
This problem is known as rendezvous. We consider deterministic distributed
rendezvous in the infinite path. Each node has a distinct label which is a
positive integer. The time of rendezvous is the number of rounds until meeting,
counted from the starting round of the earlier agent. We consider three
scenarios. In the first scenario, each agent knows its position in the line,
i.e., each of them knows its initial distance from the smallest-labeled node,
on which side of this node it is located, and the direction towards it. For
this scenario, we give a rendezvous algorithm working in time $O(D)$, where $D$
is the initial distance between the agents. This complexity is clearly optimal.
In the second scenario, each agent initially knows only the label of its
starting node and the initial distance $D$ between the agents. In this
scenario, we give a rendezvous algorithm working in time $O(D\log^*\ell)$,
where $\ell$ is the larger label of the starting nodes. We prove a matching
lower bound $\Omega(D\log^*\ell)$. Finally, in the most general scenario, where
each agent initially knows only the label of its starting node, we give a
rendezvous algorithm working in time $O(D^2(\log^*\ell)^3)$, which is at most
cubic in the lower bound. All our results remain valid (with small changes) for
arbitrary finite paths and for cycles. Our algorithms are drastically better
than approaches that use graph exploration, whose running times depend on the
graph's size or diameter. Our main methodological tool, and the main novelty of
the paper, is a two way reduction: from fast colouring of the infinite labeled
path using a constant number of colours in the LOCAL model to fast rendezvous
in this path, and vice-versa.
