The Cisco Catalyst 4503 Supervisor Engine II-Plus-TS delivers enterprise-class reliability and security for the medium-sized business. It provides twelve 10/100/1000 ports with Power over Ethernet (PoE) and eight Small Form-Factor Pluggable (SFP) ports for uplinks or server aggregation. It works in the Catalyst 4503 chassis to deliver up to 116 ports of any combination of 10/100 and 10/100/1000 data access as well as 10/100 and 10/100/1000 PoE access.
The two "core" switches have uplinks (trunks) to edge switches as
follows tva-m-cdr-1 --- edge1 --- edge2 --- tva-m-cdr-2. They work with MST costs to occupy both uplinks, eg. vlan 100 has a preferred path via tva-m-cdr-1 and vlan 200 via tva-m-cdr-2.The links they shut down is the interface on edge1 (to edge2), so no physical loop is present in the LAN