Propagated timestamps: a scheme for the stabilization of maximum-flow routing protocols

We present a distributed protocol for maintaining a maximum flow spanning tree in a network, with a designated node as the root of the tree. This maximum flow spanning tree can be used to route the allocation of new virtual circuits whose destination is the designated node. As virtual circuits are allocated and removed, the available capacity of the channels in the network changes, causing the chosen spanning tree to lose its maximum flow property. Thus, the protocol periodically changes the structure of the spanning tree to preserve its maximum flow property. The protocol is self-stabilizing, and hence it tolerates transient faults. Furthermore, it has the nice property that, while the structure of the tree is being updated, no loops are introduced, and all nodes remain connected. That is, the tree always remains a spanning tree whose root is the designated node.