Description

When debugging a PPPoE dial issue, one of the important steps is to check if the PADx packets arrive at the MX interface. This article describes how to capture the PADx packets from the VLAN ID.

Symptoms

Describe how to capture the PADx packets from the VLAN ID.

Solution


The command monitor traffic interface... can be used to capture the packets punted to the routing engine (RE). 


  1. Capture the PADx packets on the specific  VLAN.   For example, capture the PADx packets on the GE-1/1/6 and the VLAN ID is 100.  Here is an example of the command output:

monitor traffic interface ge-1/1/6 extensive matching "ether[14:2]&0xFFF= 0x64 && ether[16:2]=0x8863"

If you want to capture the PADx packets on VLAN 200, decimal 200 is equal to hexadecimal 0xC8, so replace 0x64 with 0xC8.


  • Capture the PADx packets on the specific QinQ VLAN.  For example, capture the PADx packets on the GE-1/1/6 and the SVLAN ID is 300 and CVLAN ID is 100:

monitor traffic interface ge-1/1/6 extensive matching "ether[14:2]&0x0FFF= 0x12C && ether[18:2]&0x0FFF= 0x64 && ether[20:2]=0x8863"

The 0x12C is SVLAN ID 300 and 0x64 is CVLAN ID 100.