MPLS QoS Operating Modes
Multiple modes of operation can exist when implementing QoS using MPLS. These are called the MPLS QoS tunnel modes of operation. The main tunneling modes in the MPLS QoS implementation are
Short Pipe mode
Long Pipe mode
In Uniform mode, all changes made to the class of a packet, IP Precedence, DSCP, MPLS EXP values, as the packet traverses the SP infrastructure is maintained as the packet is propagated downstream. The IP packet’s IP Precedence value is copied onto the imposed label EXP value when the packet undergoes an IP2MPLS condition. When the packet undergoes a MPLS2IP condition, the top-most label EXP value (because there is a possibility of a labeled packet having more than one ...