DiffServ with MPLS Packets
Remember the syntax of a label from Chapter 2, “MPLS Architecture”? Figure 12-4 is a refresher.
Figure 12-4. Syntax of an MPLS Label
As you can see, there are three EXP, or experimental, bits. They are called experimental, but they are really used only for QoS. You can use these bits in the same way that you use the three precedence bits in the IP header. If you use these three bits for QoS, you can call the label switched path (LSP) an E-LSP, indicating that the label switching router (LSR) will use the EXP bits to schedule the packet and decide on the drop precedence. However, when you are using MPLS, you have ...
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