Because destination MAC addresses of the mirrored packets are MAC addresses of destination hosts, SwitchB forwards the mirrored packets according to the matching entries found in its MAC address table. If no entry with MAC address 0e0-fc00-0001 and VLAN 1 exists in the MAC address table, the MAC address is learned as a dynamic MAC address entry in the MAC address table, and the hit flag of the entry is set to 1. Source MAC addresses of the mirrored packets are MAC addresses of sender hosts, which can be learned in the MAC address table of SwitchB. At t 1, packets with source MAC address 00e0-fc00-0001 and VLAN ID 1 arrive at an interface, which has joined VLAN 1. When packets sent from downstream hosts arrive at the mirrored port on SwitchA and SwitchC, SwitchA and SwitchC copy the packets and forward the mirrored packets in VLAN 10. In IEEE 802 LAN/MAN standards, the medium access control (MAC, also called media access control) sublayer is the layer that controls the hardware responsible for interaction with the wired, optical or wireless transmission medium.The MAC sublayer and the logical link control (LLC) sublayer together make up the data link layer.

All mirrored packets are forwarded in VLAN 10, and the original communication traffic between the two departments is forwarded in another VLAN. Figure 22-154 Layer 2 remote port mirroring fails when mirrored packets from different source MAC addresses are forwarded in the same VLANĪs shown in Figure 22-154, a company configures Layer 2 remote port mirroring on SwitchA and SwitchC to monitor communication traffic between the R&D and marketing departments.

Layer 2 mac address learning