6-3 
Figure 6-2 Outward-facing MEP 
 
 
Figure 6-3 Inward-facing MEP 
 
 
z  MIP 
A MIP is internal to an MD. It cannot send CFD packets actively; however, it can handle and respond to 
CFD packets. The MA and MD that a MIP belongs to define the VLAN attribute and level of the packets 
received. 
By cooperating with MEPs, a MIP can perform a function similar to ping and traceroute. Like a MEP, a 
MIP forwards packets at a higher level without any processing.   
Figure 6-4 demonstrates a grading example of the CFD module. In the figure, there are six devices, 
labeled 1 through 6 respectively. Suppose each device has two ports, and MEPs and MIPs are 
configured on some of these ports. Four levels of MDs are designed in this example, the bigger the 
number, the higher the level and the larger the area covered. In this example, the X port of device 2 is 
configured with the following MPs: a level 5 MIP, a level 3 inward-facing MEP, a level 2 inward-facing 
MEP, and a level 0 outward-facing MEP.