Hi Ibrahim,
I am not entirely certain if I understand your question well. The Uniform/Pipe QoS modes in MPLS involve the MPLS-enabled core only. On the PE-CE links, you will always see only DSCP markings; there's hardly any difference.
Either way, even if looking at the uniform and pipe modes, I do not think there is a universal answer. These QoS modes really differ depending on the needs of the customer, and needs and capabilities of the SP's network. The uniform model requires that QoS classes used and honored by the customer are also used and honored by the SP's network, and remarking in the SP's cloud will also impact the marking of the customer's traffic down to the DSCP level. The pipe models introduce two independent QoS realms, the one of the customer, the other of the SP, and while they are initially aligned when the packets enters the PE from a CE, any further remarking has no impact on the original DSCP values of the customer's traffic. The short pipe/long pipe differs in what will be used to schedule the packet at the egress PE - either the packet's own original DSCP (short pipe), or the TC/EXP bits in the packet's label.
From the customer's viewpoint, the major difference lies in whether his own markings will be preserved if the provider needs to remark the MPLS TC/EXP bits in his network. With the uniform mode, the customer's marking will indeed be changed; with pipe models, it will remain untouched. There is no "better" mode here - all depends on what the customer wants and needs.
I am sure you saw this document already but it is a very nice summary of the modes, their config examples, and their differences:
https://www.cisco.com/c/en/us/support/docs/multiprotocol-label-switching-mpls/mpls/47815-diffserv-tunnel.html
Feel welcome to ask further!
Best regards,
Peter
