MPLS is a packet-switching technology that integrates link layer (Layer 2) switching with network layer (Layer 3) routing. With MPLS, data is transferred over any combination of Layer 2 technologies, using any Layer 3 protocol, with increased scalability. In Catalyst 3750 Metro Switches MPLS functionality is supported only on the enhanced-services (ES) ports.
The Catalyst 3750 Metro switch must connect to the MPLS network through an ES port, since MPLS configuration is supported only on the ES ports. Other supported features on the ES ports include EoMPLS, MPLS VPNs, bidirectional hierarchical QoS, intelligent 802.1Q tunneling (Q-in-Q) with CoS mutation, and VLAN ID translation.