There is so much about MPLS and how MPLS works. Here I wrote some simple introductory lines about it but only from one perspective. The costumer side one. There is nothing here about BGP and all the things that need to be done and configured in order for MPLS to function in ISP cloud. As an introductory in MPLS this text will take you to the central office and branch side of the MPLS configuration and in this way it will be simpler to explain and enter in the world of MPLS networking technology.
In MPLS networks, packets are sending with special MPLS prefix before IP packet data. With an MPLS header that is sometimes mentioned as a label stack. In MPLS header there are labels, every label with some value:
- Traffic-class field, important for quality of service – QoS
- Bottom-of-stack flag
- 8-bit time-to-live – TTL field