Nokia 7705 SAR-W Series Manual page 27

MPLS Guide
The ELI is inserted by the iLER. The ELI is a special-purpose MPLS label (value = 7)
that indicates that the entropy label is the next label in the stack.
Entropy label capability is advertised at the tunnel level by the far-end node (eLER).
This capability can be advertised for an RSVP-TE FEC or an SR-TE tunnel on IS-IS
or OSPF. Capability signaling is not supported for point-to-multipoint LSPs, BGP
tunnels, or LDP FECs. An LSR used for RSVP-TE and SR-TE tunnels will pass the
entropy label capability signal from the downstream LSP segment to upstream peers.
However, earlier releases that do not support entropy label functionality will pass the
capability flag transparently, without altering the value.
The insertion of an entropy label by the upstream LER on a tunnel enabled for
entropy label capability is enabled on a per-service basis. The entropy label is only
inserted if the downstream peer has signaled entropy label support. The upstream
LER only inserts a single entropy label, even if multiple LSP labels exist in a label
stack.
The 7705 SAR supports the entropy label feature for the following services:
Entropy label capability on RSVP-TE LSPs is enabled on the eLER using the
config>router>rsvp>entropy-label-capability command.
At the iLER, the insertion of the entropy label into the label stack is enabled using the
entropy-label command under the service, mesh SDP, or spoke SDP context or
under the config>router>isis (or ospf)>segment-routing context for SR-TE LSPs.
The entropy label requires the insertion of two additional labels in the label stack. In
some cases, this may result in an unsupported label stack depth or large changes in
the label stack depth during the lifetime of an LSP (for example, due to switching from
a primary path with entropy label capability enabled to a secondary path for which
the far end has not signaled entropy label capability).
3HE 18686 AAAB TQZZA
• Cpipe, Epipe, and Ipipe access to spoke SDP
• Cpipe, Epipe, and Ipipe spoke SDP to spoke SDP (vc-switching)
• VPLS SAP to VPLS spoke SDP or mesh SDP
• VPLS spoke SDP to VPLS spoke SDP
• VPRN for RSVP-TE
• R-VPLS
• IGP shortcut
• IS-IS for SR-TE
• OSPF for SR-TE
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MPLS and RSVP-TE
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