Traffic Engineering - Alcatel-Lucent 7950 SR User Configuration Manual

Traffic Engineering

Traffic Engineering
Without traffic engineering, routers route traffic according to the SPF algorithm, disregarding
congestion or packet types.
With traffic engineering, network traffic is routed efficiently to maximize throughput and
minimize delay. Traffic engineering facilitates traffic flows to be mapped to the destination
through a different (less congested) path other than the one selected by the SPF algorithm.
MPLS directs a flow of IP packets along a label switched path (LSP). LSPs are simplex, meaning
that the traffic flows in one direction (unidirectional) from an ingress router to an egress router.
Two LSPs are required for duplex traffic. Each LSP carries traffic in a specific direction,
forwarding packets from one router to the next across the MPLS domain.
When an ingress router receives a packet, it adds an MPLS header to the packet and forwards it to
the next hop in the LSP. The labeled packet is forwarded along the LSP path until it reaches the
destination point. The MPLS header is removed and the packet is forwarded based on Layer 3
information such as the IP destination address. The physical path of the LSP is not constrained to
the shortest path that the IGP would choose to reach the destination IP address.
Page 52 7950 SR OS MPLS Configuration Guide