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MPLS Guide
Note: For the hop-to-label translation to operate, the user must enable TE on the network
links by adding the network interfaces to MPLS and RSVP. In addition, the user must enable
the traffic-engineering option on all participating router IGP instances. If a router has the
database-export option enabled in the participating IGP instances to populate the TE-DB
with the learned IGP link-state information, then enabling of the traffic-engineering option
is not required. For consistency, it is recommended that the traffic-engineering option
always be enabled.
3HE 18686 AAAB TQZZA
- All IGP instances are scanned from the lowest to the highest instance ID,
beginning with IS-IS instances and then the OSPF instance; not only the
IGP instance that resolved the prefix of the destination address of the LSP
in the RTM is used. For the first instance where all specified path hop
addresses can be translated, the label stack is selected. The hop-to-SID/
label translation tool does not support paths that cross area boundaries. All
SID/labels of a given path are therefore taken from the same IGP area and
instance.
2. The ingress LER validates the first hop of the path to determine the outgoing
interface and next hop to forward the packet to, and programs the data path
according to the following conditions.
- If the first hop corresponds to an adjacency SID (host address of next hop
on the link's subnet), the adjacency SID label is not pushed. In other words,
the ingress LER treats forwarding to a local interface as a push of an implicit
null label.
- If the first hop is a node SID of a downstream router, the node SID label is
pushed.
In both cases, the SR-TE LSP tracks and uses the SR shortest path tunnel of
the SID of the first hop.
3. If the router is configured as a PCC and has a PCEP session to a PCE, the router
sends a PCRpt message to update the PCE with the Up state and the RRO
object for each LSP that has the pce-report option enabled. The PE router does
not set the delegation control flag to keep LSP control. The state of the LSP is
now synchronized between the router and the PCE.
Use subject to Terms available at: www.nokia.com
© 2022 Nokia.
MPLS and RSVP-TE
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