QoS in a hybrid model with service provider WAN

We have discussed the QoS requirements within the enterprise network. The enterprise network also spreads across the WAN, and the WAN can consist of dedicated TDM links, layer-2 links, or even layer-3 VPNs from the service provider.

If the organization's WAN is based on dedicated TDM circuits, there is no need for QoS on the SP backbone. However, if the organization takes a layer-3 VPN from the SP, the packets of the organization would be carried over the SP network that would also carry traffic from other organizations, and can be congested at times, as it is a shared infrastructure.

Hence the organization takes a layer-3 VPN from the SP, with quality of service enabled. This means that the SP would honour the QoS requirements of the organization. Since the SP network has a uniform QoS marking design for its network that is shared across multiple customers, the SP would rewrite the SP markings of the organization if they don't align to the SP...