Detailed MPLS Principles

MPLS: Multiprotocol label Switching. What exactly is MPLS ?

1, MPLS Overview: The use of label forwarding instead of traditional routing and forwarding, greatly improve the forwarding rate, and MPLS in traffic engineering and QoS areas are of great use.

2. Tags: MPLS uses tags to forward data, so how are labels generated and distributed? Tags are allocated through the LDP protocol, so how is the LDP protocol session established, and how is the protocol data exchanged between the two devices?

3, LDP: First on the device to open the LDP function, the device will send the LDP group broadcast text, to obtain the information of their neighbors and then establish a TCP and UDP session. The labels are then automatically or manually assigned.

For the LDP session setup process, please wait ...

4. MPLS Data Forwarding Analysis

First IP packet A into RT1 (router), RT1 received, first find the FIB table, according to the TUNNL value in the FIB table, if the TUNNL value is zero, enter the normal IP forwarding, if not zero based on TUNNL value lookup Nhlfe table for label processing and forwarding.

RT2 after receiving the label package, the process flow: Find the ILM table based on the label to determine the TUNNL value, and find the Nhlfe table for label processing and forwarding based on the TUNNL value.

RT3 after receiving the label package: Find the ILM table based on the label to determine the TUNNL value, depending on the TUNNL value to determine whether MPLS forwarding or IP forwarding.

This article is from the "Computer Principles Analysis" blog, please be sure to keep this source http://2556110.blog.51cto.com/2546110/1772538

Detailed MPLS Principles