Dell PowerSwitch S4820T Configuration Guide for the S4820T System 9.112.1P1 - Page 266

DCBx Example The following figure shows how to use DCBx. The external 40GbE 40GbE ports on the base module (ports 33 and 37) of two switches are used for uplinks configured as DCBx autoupstream ports. The device is connected to third-party, top-of-rack (ToR) switches through 40GbE uplinks. The ToR switches are part of a Fibre Channel storage network. The internal ports (ports 1-32) connected to the 10GbE backplane are configured as auto-downstream ports. On the S4820T, PFC and ETS use DCBx to exchange link-level configuration with DCBx peer devices. Figure 30. DCBx Sample Topology DCBx Prerequisites and Restrictions The following prerequisites and restrictions apply when you configure DCBx operation on a port: • For DCBx, on a port interface, enable LLDP in both Send (TX) and Receive (RX) mode (the protocol lldp mode command; refer to the example in CONFIGURATION versus INTERFACE Configurations in the Link Layer Discovery Protocol (LLDP) chapter). If multiple DCBx peer ports are detected on a local DCBx interface, LLDP is shut down. • The CIN version of DCBx supports only PFC, ETS, and FCOE; it does not support iSCSI, backward congestion management (BCN), logical link down (LLDF), and network interface virtualization (NIV). Configuring DCBx To configure DCBx, follow these steps. For DCBx, to advertise DCBx TLVs to peers, enable LLDP. For more information, refer to Link Layer Discovery Protocol (LLDP). Configure DCBx operation at the interface level on a switch or globally on the switch. To configure the S4820Tsystem for DCBx operation in a data center network, you must: 1 Configure ToR- and FCF-facing interfaces as auto-upstream ports. 2 Configure server-facing interfaces as auto-downstream ports. 266 Data Center Bridging (DCB)