Introduction To Mpls Ldp; Mpls Ldp Features Supported By The S9300 - Huawei Quidway S9300 series Configuration Manual

Quidway S9300 Terabit Routing Switch
Configuration Guide - MPLS

2.1 Introduction to MPLS LDP

Through LDP, LSRs can map the route information at the network layer to the switched paths
at the data link layer to set up network layer LSPs.
With the prevalence of the Internet early in the 1990s, the IP technology that adopts the longest
match for search becomes a bottleneck in forwarding over networks due to limitation of the
hardware technology. The ATM technology uses labels with fixed lengths and maintains a label
table with a size much smaller than the size of the routing table. Therefore, compared with IP
technology, the ATM technology can provide higher forwarding rate.
The traditional IP technology is simple to implement but limited in performance. The ATM
technology has better performance but is difficult to popularize because of its complex signaling
and high cost in deployment. The MPLS technology thus emerges to combine the advantages
of IP and ATM technologies.
Initially, MPLS emerges to speed up the forwarding of the device. With the development of the
ASIC technology, the speed of routing is not the bottleneck to the network development. MPLS,
however, does not feature in high-speed forwarding. As MPLS supports multi-layer labels, the
connection-oriented forwarding plane, and the connectionless-oriented control plane, MPLS is
widely used in VPN, TE, and QoS.

2.2 MPLS LDP Features Supported by the S9300

MPLS LDP features supported by the system include LDP sessions, LDP LSPs, LDP multi-
instance, BFD for LDP LSPs, LDP FRR, LDP and IGP synchronization, LDP GTSM, and LDP
GR.
LDP Sessions
Label Distribution Protocol (LDP) sessions are used between LSRs to swap labels.
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LDP LSP
The LDP protocol is used to create dynamic LSPs. If you need not to strictly control the setup
process of LSPs or to deploy traffic engineering (TE) on an MPLS network, you are
recommended to use LDP to set up LSPs.
BFD for LDP LSP
BFD can detect faults on the data plane of the LDP LSP forwarding path. At the same time, the
format of BFD packets is constant, adaptive to implementation in hardware and traversal through
the firewall. The advantages of BFD for the data plane of LDP LSP are as follows:
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At present, in the S9300, BFD can detect LSPs of the following types:
Issue 04 (2011-12-26)
Local LDP session: can be set up only between adjacent LSRs.
Remote LDP session: can be set between all the LSRs.
Quick detection
Wide range of failure detection for LSPs
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