Hello Ratheesh
The scenario you refer to deals with DiffServ-aware Traffic Engineering for MPLS, or DS-TE MPLS. This is an enhancement to standard MPLS-TE. In MPLS-TE, you can reserve bandwidth for tunnels but all reservations come from the same single “global” bandwidth pool. This means that high-priority traffic (like voice or video) could be blocked if lower-priority tunnels have already consumed the available TE bandwidth.
DS-TE introduces the concept of multiple bandwidth pools, allowing you to create a global pool, as well as sub-pools. You can define multiple class types, wich for different categories of traffic. When this is done, RSVP knows whether it should take bandwidth from the global pool or the sub-pool based on the tunnel’s class-type.
Traditional MPLS DS-TE supports only a global pool, and a single sub-pool. To achieve what you are describing, you’d need to use MPLS DS-TE IETF mode. you can find out more about that at this lesson here:
This mode allows multiple sub-pools as you your scenario, and can support multiple class types as well as bandwidth constraints.
I hope this has been helpful!
Laz