H3C Technologies H3C SR8800 - Manual (Page 52)

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MPLS TE configuration
MPLS TE overview
Traffic engineering and MPLS TE
Let us get familiar with traffic engineering (TE) before going on to MPLS-TE.
Network congestion is one of the major problems that can degrade your network backbone
performance. It may occur either when network resources are inadequate or when load distribution is
unbalanced. TE is intended to avoid the latter situation where partial congestion may occur as the result
of inefficient resource allocation.
TE can make best utilization of network resources and avoid non-even load distribution by real-time
monitoring traffic and traffic load on each network elements to dynamically tune traffic management
attributes, routing parameters and resources constraints.
The performance objectives associated with TE can be either of the following:
• Traffic oriented. These are performance objectives that enhance Quality of Service (QoS) of traffic
streams, such as minimization of packet loss, minimization of delay, maximization of throughput
and enforcement of service level agreement (SLA).
• Resource oriented. These are performance objectives that optimize resources utilization. Bandwidth
is a crucial resource on networks. Efficiently managing it is one major task of TE.
To implement TE, you can use interior gateway protocols (IGPs) or Multiprotocol Label Switching (MPLS).
Because IGPs are topology-driven and consider only network connectivity, they fail to present some
dynamic factors such as bandwidth and traffic characteristics.
This IGP disadvantage can be repaired by using an overlay model, such as IP over ATM or IP over FR.
An overlay model provides a virtual topology above the physical network topology for a more scalable
network design. It also provides better traffic and resources control support for implementing a variety of
traffic engineering policies.
Despite all the benefits, overlay models are not suitable for implementing traffic engineering in
large-sized backbones because of their inadequacy in extensibility. In this sense, MPLS TE is a better
traffic engineering solution for its extensibility and ease of implementation.
MPLS is better than IGPs in implementing traffic engineering for the following reasons:
• MPLS supports explicit LSP routing.
• LSP routing is easy to manage and maintain compared with traditional packet-by-packet IP
forwarding.
• Constraint-based Routed Label Distribution Protocol (CR-LDP) is suitable for implementing a variety
of traffic engineering policies.
• MPLS TE uses less system resources compared with other traffic engineering implementations.
MPLS TE combines the MPLS technology and traffic engineering. It delivers these benefits:
• Reserve resources by establishing LSP tunnels to specific destinations. This allows traffic to bypass
congested nodes to achieve appropriate load distribution.