The term CT is used when describing MPLS Diffserv aware Traffic Engineering. CT is used for the purpose of link bandwidth allocation, constraint based routing and admission control. For example, CT 1 may define a class of traffic associated with low latency requirements. That CT will be allocated a specific amount of bandwidth on the link. That portion of bandwidth will be populated by LSP (Label Switched Path) of CT 1 only. If the bandwidth of CT 1 is fully utilized, further attempts to set up LSP supporting CT 1 traffic will fail.