Mpls Architecture; Mpls Network Structure; Lsp Establishment - 3Com 3C13636 Configuration Manual

Router 3000 ethernet family

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3Com Router 3000 Ethernet Family

Configuration Guide

1.3 MPLS Architecture

The basic composing unit of MPLS network is LSR (Label Switching Router). It runs

MPLS control protocol and L3 routing protocol, exchanges routing messages with other

LSRs and create the routing table, maps FECs with IP packet headers, binds FECs

with labels, distributes label binding messages, establishes and maintains label

forwarding table.

The network consisting of LSRs is called MPLS domain. The LSR that is located at the

edge of the domain edge LSR (LER, Labeled Edge Router). It connects an MPLS

domain with a non-MPLS domain or with another MPLS domain, classifies packets,

distributes labels (as egress LER) and distracts labels. The ingress LER is termed as

ingress and egress LER as egress.

The LSR located inside the domain is called core LSR. The core LSR can be either the

router that supports MPLS or the ATM-LSR upgraded from ATM switch. It achieves

label swapping and label distribution. The labeled packets are transmitted along the

LSP (Label Switched Path) composed of a series of LSRs.

MPLS Edge LSR (LER)

Figure 1-3 MPLS basic principle

Actually, LSP establishment refers to the process of binding FEC with the label, and

then advertising this binding to the adjacent LSR on LSP. This process is implemented

via Label Distribution Protocol (LDP). LDP regulates the message in interactive

processing and message structure between LSRs as well as routing mode. Refer to the

following section for the detail description of LDP

3Com Corporation

Label Switched Path (LSP)

MPLS Core LSR

Chapter 1 MPLS Architecture

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3c13636-us - router 3036 3000 series