Brocade Communications Systems 53-1002163-02 manual Layer 2 Ethernet overview, Layer 2 forwarding

Layer 2 Ethernet overview 1

Layer 2 Ethernet overview

The Brocade FCoE hardware contain CEE ports that support FCoE forwarding. The CEE ports are also backwards compatible and support classic Layer 2 Ethernet networks (see Figure 1). In Layer 2 Ethernet operation, a host with a Converged Network Adapter (CNA) can be directly attached to a CEE port on the Brocade FCoE hardware. Another host with a classic 10-Gigabit Ethernet NIC can be either directly attached to a CEE port, or attached to a classic Layer 2 Ethernet network which is attached to the Brocade FCoE hardware.

FIGURE 1 Multiple switch fabric configuration

	Classic Layer 2
	Ethernet switch		Host 3
		Classic NIC
Host 1	Brocade 8000		Host 2
	switch

CNA or

classic NIC

CNA or

classic NIC

FC switch

FC switch

Storage

Layer 2 forwarding

Layer 2 Ethernet frames are forwarded on the CEE ports. 802.1Q VLAN support is used to tag incoming frames to specific VLANs, and 802.3ac VLAN tagging support is used to accept VLAN tagged frames from external devices. The 802.1D Spanning Tree Protocol (STP), Rapid Spanning Tree Protocol (RSTP), and Multiple Spanning Tree Protocol (MSTP) are used as the bridging protocols between Layer 2 switches.

The Brocade FCoE hardware handles Ethernet frames as follows:

•When the destination MAC address is not in the lookup table, the frame is flooded on all ports except the ingress port.

•When the destination MAC address is present in the lookup table, the frame is switched only to the correct egress port.

•When the destination MAC address is present in the lookup table, and the egress port is the same as the ingress port, the frame is dropped.

Converged Enhanced Ethernet Administrator’s Guide	3
53-1002163-02