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MPLS and RSVP-TE
The next requirement is to trigger the creation of single-hop LSPs using the auto-lsp
lsp-template command:
config>router>mpls>auto-lsp lsp-template template-name one-hop
The LSP and path parameters and options supported in an LSP template of type
one-hop-p2p are the same as those in the LSP template of type mesh-p2p. The
show command for auto-lsp will display the actual outgoing interface address in the
"from" field.
The auto-created single-hop LSP can be signaled over both numbered and
unnumbered RSVP-TE interfaces.
When the one-hop command is executed, the TE database keeps track of each TE
link to a directly connected IGP neighbor whose router ID is discovered. MPLS then
signals an LSP with a destination address matching the router ID of the neighbor and
with a strict hop consisting of the address of the interface used by the TE link. The
auto-lsp command with the one-hop option results in one or more LSPs signaled to
the IGP neighbor.
Only the router ID of the first IGP instance of the neighbor that advertises a TE link
causes the LSP to be signaled. If another IGP instance with a different router ID
advertises the same TE link, no action is taken and the existing LSP is kept up. If the
router ID originally used disappears from the TE database, the LSP is kept up and is
now associated with the other router ID.
The state of a single-hop LSP that is signaled displays the following behavior.
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• If the interface used by the TE link goes down or BFD times out and the
RSVP-TE interface is registered with BFD, the LSP path moves to the bypass
backup LSP if the primary path is associated with one.
• If the association of the TE link with a router ID is removed from the TE database
while the single-hop LSP is up, the single-hop LSP is torn down whether the
bypass backup path is activated or not. This occurs if the interface used by the
TE link is deleted or if the interface is shut down in the context of RSVP-TE.
• If the TE database loses the router ID while the LSP is up, it will perform two
separate updates to MPLS, whether the bypass backup path is activated or not.
The first one updates the loss of the TE link association, which will cause the
single-hop LSP to be torn down. The other update states that the router ID is no
longer in the TE database, which will cause MPLS to tear down all mesh LSPs
to this router ID. A shutdown at the neighbor of the IGP instance that advertised
the router ID will cause the router ID to be removed from the ingress LER node
immediately after the last IGP adjacency is lost and not be subject to time-out as
it is for a non-directly connected destination router.
Use subject to Terms available at: www.nokia.com
© 2022 Nokia.
MPLS Guide
3HE 18686 AAAB TQZZA
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