8.3. Configuring Phy Loopback

Overview

Function Introduction

Phy loopback is a proprietary based loopback. There are 2 types of phy loopback: phy(including internal and external) level loopback and port level loopback.

  • If a physical port is configured as “external phy loopback”, all packets coming into this port should be loopback back from the port itself at phy level.

  • If a physical port is configured as “internal phy loopback”, all packets expected out from this port should be looped back to specified physical port.

  • If a physical port is configured as “port loopback”, all packets coming into this port should be looped back from the port itself, and whether to swap the SMAC with the DMAC should be selectable by users. And if the MAC is swapped, the CRC should be recalculated.

Principle Description

N/A

Configuration

Configuring external phy loopback

image

Fig. 8.2 External phy topology

step 1 Enter the configure mode

Switch# configure terminal

step 2 Enter the interface configure mode and set loopback phy external

Switch(config)# interface eth-0-1
Switch(config-if)# no shutdown
Switch(config-if)# loopback phy external

step 3 Exit the configure mode

Switch(config-if)# end

step 4 Validation

Switch# show phy loopback
Interface Type DestIntf SwapMac
 --------------------------------------------
eth-0-1 external - -
 --------------------------------------------

Configuring internal phy loopback

image

Fig. 8.3 Internal phy topology

step 1 Enter the configure mode

Switch# configure terminal

step 2 Enter the interface configure mode and set loopback phy internal and specify the destination interface

Switch(config)# interface eth-0-2
Switch(config-if)# no shutdown
Switch(config-if)# exit
Switch(config)# interface eth-0-1
Switch(config-if)# no shutdown
Switch(config-if)# loopback phy internal eth-0-2

step 3 Exit the configure mode

Switch(config-if)# end

step 4 Validation

Switch# show phy loopback
Interface Type DestIntf SwapMac
 --------------------------------------------
eth-0-1 internal eth-0-2 -
 --------------------------------------------

Configuring port level loopback

image

Fig. 8.4 Port level topology

step 1 Enter the configure mode

Switch# configure terminal

step 2 Enter the interface configure mode and set loopback phy mac-address swap

Switch(config)# interface eth-0-1
Switch(config-if)# no shutdown
Switch(config-if)# loopback port mac-address swap

step 3 Exit the configure mode

Switch(config-if) end

step 4 Validation

Switch# show phy loopback
Interface Type DestIntf SwapMac
 --------------------------------------------
eth-0-1 port - yes
 --------------------------------------------

Application cases

N/A