# Pass Through

### 1. Function Overview

Pass through is a function that forwards frames addressed to reserved special MAC addresses without discarding them, which would normally be discarded by a normal switch.
This product supports pass-through of BPDU frames used in the spanning tree protocol and EAP frames used in IEEE 802.1X authentication.
When the BPDU pass through is enabled, this product can be installed between switches that use the spanning tree protocol.
When EAP pass through is enabled, this product can be installed between an IEEE 802.1X authenticated switch and a computer.

### 2. Definition of Terms Used

BPDU (Bridge Protocol Data Unit)

This is a message used in the spanning tree protocol to avoid loops between compatible devices.

EAP (Extended authentication protocol)

This is an authentication protocol that extends PPP, allowing various authentication methods to be used. This protocol is defined in RFC 3748.
IEEE 802.1X authentication supports the use of this protocol.

### 3. Function Details

#### 3.1. Operating specifications for BPDU pass through

The specifications for BPDU pass through are indicated below.

1. By enabling BPDU pass through, received BPDU frames can be forwarded without being discarded.
   If BPDU pass through is disabled, received BPDU frames will be discarded and will not be forwarded.

2. BPDU frames are forwarded to all ports except the port on which the frames were received, regardless of the settings for tagged VLAN, port-based VLAN, and multiple VLAN.

3. You can enable or disable BPDU pass through using the pass-through bpdu command or by navigating to [Detailed settings] - [Pass through] in the web GUI.
   This function is enabled by default.

4. The BPDU pass through setting is applied on a system-wide basis (common to all ports).

#### 3.2. Operating specifications for EAP pass through

The specifications for EAP pass through are indicated below.

1. By enabling EAP pass through, received EAP frames can be forwarded without being discarded.
   If EAP pass through is disabled, received EAP frames will be discarded and will not be forwarded.

2. EAP frames are forwarded in the same way as normal multicast frames, according to the settings for tagged VLAN, port-based VLAN, and multiple VLAN.

3. You can enable or disable EAP pass through using the pass-through eap command or by navigating to [Detailed settings] - [Pass through] in the web GUI.
   This function is enabled by default.

4. The EAP pass through setting is applied on a system-wide basis (common to all ports).

### 4. Related Commands

Related commands are indicated below.
For command details, refer to the command reference.

Operations | Operating commands
--- | ---
Enable/disable BPDU pass through | pass-through bpdu
Enable/disable EAP pass through | pass-through eap

### 5. Examples of Command Execution

Enable BPDU pass through for installing this product between switches that use the spanning tree protocol.

- Enable BPDU pass through.

      Yamaha(config)#pass-through bpdu enable (1)

  1 | Enable BPDU pass through

Enable EAP pass through for installing this product between an IEEE 802.1X authenticated switch and a computer.

- Enable EAP pass through.

      Yamaha(config)#pass-through eap enable (1)

  1 | Enable EAP pass through

### 6. Points of Caution

None

### 7. Related Documentation

None

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