l MPLS
network forwards packet according to the label. But how does label be
generated? What mechanism does MPLS adopt to implement data forwarding?
l MPLS
includes two plane: control plane and data plane.
l Control
plane’s charge is to generate and maintain routing information and label
information. Data plane’s charge is conventional IP packet forwarding and
labeled packet forwarding.
l In
control plane, routing protocol module is used to transmit routing information,
generate routing table; label distribution protocol is used to complete
exchange of label and establish label switch path.
l Data
plane includes IP forwarding table and label forwarding table, when receiving
conventional IP packets, if it is conventional IP forwarding, it should lookup
routing table and forward, if it is label forwarding, it should forward by the
label forwarding table; when receiving labeled packets, if it needs to forward
by label, it should forward by label forwarding table, if it needs to transmit
to IP network, it should remove label and forward by IP routing table.
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