H3C Technologies H3C SR8800 - Manual (Page 12)

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Configuring basic MPLS
NOTE:
•
For information about VPN, see the chapters “Configuring MPLS L2VPN” and “Configuring MPLS
L3VPN.”
• For information about MPLS TE, see the chapter “Configuring MPLS TE.”
MPLS overview
Multiprotocol Label Switching (MPLS) is a new IP backbone technology. It introduces connection-oriented
label switching into connectionless IP networks, and seamlessly integrates the flexibility of IP routing and
the simplicity of Layer 2 switching.
MPLS is widely used on large-scale networks for it features the following advantages:
• On an MPLS network, devices forward packets according to short- and fixed-length labels, instead
of doing Layer 3 header analysis and complicated routing table lookup independently. This is a
highly effective and fast data transmission method on backbone networks.
• Residing between the link layer and the network layer, MPLS can work on various link layer
protocols (for example, PPP, ATM, frame relay, and Ethernet), provide connection-oriented services
for various network layer protocols (for example, IPv4, IPv6, and IPX), and work with mainstream
network technologies.
• As MPLS is connection-oriented and supports label stack, it is used in various services, such as VPN,
traffic engineering, and QoS.
Basic concepts
FEC
As a forwarding technology based on classification, MPLS groups packets with the same characteristics
(such as packets with the same destination or service class) into a class, called a “forwarding
equivalence class (FEC)”. Packets of the same FEC are handled in the same way on an MPLS network.
The device supports classifying FECs according to the network layer destination addresses of packets.
Label
A label is a short, fixed length identifier for identifying a single FEC. A label is locally significant and
must be locally unique.
Figure 1 Format of a label