1. Label switching principles
Before detailing the MPLS protocol and the label distribution protocols used to establish paths, we describe the principles of label switching and the various solutions that were proposed before MPLS took shape.
1.1 Label switching
We saw (introduction) that a label was added to the IP packet, but we didn't specify how this was done. Depending on the proposal, this label is simply found in the header of the level 2 frame (IP Switching) or in a header added between the level 2 header and the IP header (Tag Switching, MPLS). In the former case, the core routers use Level 2 processing logic, while in the latter, routers and switches have to be slightly modified to learn how to process a new, very simple header. Thus, MPLS is often referred to as a Layer 2.5 protocol,...
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Label switching principles
MultiProtocol Label Switching
Bibliography
References
Organizations
Internet Engineering Task Force (IETF)
The IETF website provides access to documents produced by IETF working groups, in particular the MPLS, Traffic Engineering and VPN groups.
IETF MPLS working group
...Websites
MPLS Resource Center
A resource site, this portal provides access to a wide range of documentation on MPLS: books and articles, announcements from manufacturers and network operators, vendors of products supporting MPLS, LDP and administration tools. You'll also find information on technologies associated with MPLS: GMPLS,...
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