End-To-End Testing Of Paths In An Ldp Ecmp Network - Alcatel-Lucent 7750 SR OS Service Manual

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OAM Overview

End-to-End Testing of Paths in an LDP ECMP Network

LDP re-converge. The impacted traffic will be forwarded on the next available ECMP path as

determined by the hash routine at the node that had a link failure.

However, there are faults which the IGP/LDP control planes may not detect. These faults are

mainly due to a corruption of the control plane state or of the data plane state in a node. The LDP

ECMP OAM is intended to detect these "silent" data plane and control plane faults. For example,

it is possible that the forwarding plane of a node has a corrupt Next Hop Label Forwarding Entry

(NHLFE) and keeps forwarding packets over an ECMP path only to have the downstream node

discard them. This data plane fault can only be detected by an OAM tool that can test all possible

end-to-end paths between the ingress LER and the egress LER. A corruption of the NLHFE entry

can also result from a corruption in the control plane at that node.

Figure 4: Network Resilience Using LDP ECMP

depicts faults that are detected through IGP and/or LDP are corrected as soon as IGP and

7750 SR OS Services Guide