GMPLS
7450 ESS MPLS Guide Page 451
using a new SRLG flag. This path would be the primary path for a gLSP
established by the 7x50 UNI-C. As long as the SRLG information flag is set in the
PATH message, the UNI-N node inserts the SRLG sub-object as defined in draft-
ietf-ccamp-rsvp-te-srlg-collect-04.txt into the RSVP RESV message that contains
the current SRLG information for the gLSP path. Note that the provider network's
policy may have been configured so as not to share SRLG information with the
client network. In this case the SRLG sub-object is not inserted in the RESV
message even if the SRLG information flag was set in the received PATH
message. Note that the SRLG information is assumed to be always up-to-date by
the UNI-C.
→ Establishment of a new gLSP path with SRLG diversity constraints — When a
dual-homed UNI-C device sends an LSP setup requests to a UNI-N for a new
gLSP path that is required to be SRLG diverse with respect to an existing gLSP
path that is entering the optical network via another UNI-N, the UNI-C sets a new
SRLG diversity flag in the LSP attributes sub-object of the PATH message that
initiates the setup of this new gLSP path. This path would be the protect path of a
gLSP established by the 7x50. When the UNI-N receives this request it calculates
a path to the given destination and uses the received SRLG information as path
computation constraints.
In Release 13.0, the 7x50 collects SRLG by default. SRLG collection occurs on all paths of
the gLSP. The collected SRLG list is visible to the user via a show command. The recorded
SRLGs are then used to populate the XRO. Only best effort (ie. loose) SRLG diversity is
supported.
Automated SRLG diversity is supported for the working paths of the following end to end
protection types in Release 13.0R1:
• LSPs that form a part of a load sharing tunnel group
Already-established gLSPs within a load-sharing tunnel group can be made mutually diverse
by applying a shutdown / no shutdown operation. GMPLS LSPs with other types of
protection can be made mutually SRLG-diverse by performing a shutdown of the gLSP,
reconfiguring the SLG list to exclude using the exclude-srlg command, and then applying a
no shutdown of the gLSP.
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