Hi Josh,
The Cisco Catalyst 3750 Metro Series is built for Metro Ethernet access in a customer location, enabling the delivery of more differentiated Metro Ethernet services. These switches feature bidirectional hierarchical QoS and Traffic Shaping, intelligent 802.1Q tunneling with class-of-service (CoS) mutation, VLAN translation, MPLS, EoMPLS, and Hierarchical Virtual Private LAN Service (H-VPLS) support, and redundant AC or DC power. They are ideal for service providers seeking to deliver profitable business services, such as Layer 2, Layer 3, and MPLS VPNs, in a variety of bandwidths and with different SLAs.
The metro switches have the PXF chips (which allow hierarchical QoS on the 2 "WAN" GigE ports, so several logical links can share a connection, and have soft bandwidth limits).
For more details on 3750-M switches have a look at this link
http://www.cisco.com/en/US/products/hw/switches/ps5532/products_qanda_item09186a00801eb822.shtml
HTH
Ankur
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