  In this article we present a protocol for building dense numeration in
network with unknown topology. Additionally to a unique number each node as
result of the protocol will get information about a spanning tree. This
spanning tree is constructed during BFS search from the leader node. This
property of the numeration can be useful in other tasks, as example we present
a protocol for searching bridges in network. The time of numeration building in
our protocol is linear in network size, simple informational lower bounds also
linear (it is required at least linear number of bits for code tree structure).
In bridges searching problem our protocol also heats lower linear bound: in
result each node knows about all bridges.
