Size optimization

The size of TC messages is reduced due to the fact that a node may only declare its MPR selectors in TC messages. The factor of this reduction is related to how dense the network topology is. In a topology as shown in figure 3.3 the TC message size of the center node would be reduced to half the size of a ``classical'' TC message(not including headers). When using IPv6, a simple example like this reduces a net-wide broadcast message with 64 bytes.