Tmix uses ns-2 to model the TCP-level interaction between two nodes on the simulated link. To simulate network-level effects of TCP transfer through the clouds, use Tmix_DelayBox. Tmix_DelayBox is derived from DelayBox (Chapter 22). Tmix_DelayBox simply adds the ability to specify delays and losses for each connection using a connection vector file instead of setting up rules for each source-destination pair. After a connection vector file is specified, Tmix_DelayBox parses each connection vector to obtain the loss rate and delay, which are written into the DelayBox flow table. Note that the current version of Tmix_DelayBox does not allow bandwidth limitations as does DelayBox, but that future versions may support this.