25.5.1 Overview

L2 protocol frame transparency functionality forwards Layer 2 protocol frames. The frames to be forwarded include EAPOL,LLDP frame of the spanning tree BPDU,IEEE802.1X and OAMPDU of IEEE802.3ah/UDLD. Usually, protocol frames for these layers are not forwarded.

The frames forwarded are handled as simple multicast frames on the Switch, and are not used as protocols by the Switch.

<Structure of this section>

(1) BPDU forwarding function

The Switch can forward BPDUs when Spanning Tree Protocols are not used. When this functionality is used with VLAN tunneling, user BPDUs can be forwarded. In this case, BPDU forwarding functionality needs to be set for all edge switches and core switches on the VLAN-tunneled network.

(2) EAPOL forwarding function

The Switch can forward EAPOLs when IEEE 802.1X is not used. This functionality is used for the Switch when an L2 switch is used between the Authenticator and terminal (Supplicant).

Figure 25-4: Application of EAPOL Forwarding Feature

(3) LLDP forwarding function

LLDP frames can be forwarded when the Switch does not use LLDP.

(4) UDLD forwarding function

You can relay OAMPDU when the Switch does not use UDLD.