Alcatel-Lucent 7450 - Operation of RSVP FRR Facility Backup over Unnumbered Interface

MPLS and RSVP
7450 ESS MPLS Guide Page 57
PathErr message will be sent back to the ingress LER with the Routing Problem error code of 24
and an error value of 5 “No route available toward destination”.
All MPLS features available for numbered IP interfaces are supported, with the exception of the
following:
• Configuring a router-id with a value other than system.
• Signaling of an LSP path with an ERO based a loose/strict hop using an unnumbered TE
link in the path hop definition.
• Signaling of one-to-one detour LSP over unnumbered interface.
• Unnumbered RSVP interface registration with BFD.
• RSVP Hello and all Hello related capabilities such as Graceful-restart helper.
• The user SRLG database feature. The user-srlg-db option under MPLS allows the user to
manually enter the SRLG membership of any link in the network in a local database at the
ingress LER. The user cannot enter an unnumbered interface into this database and as
such, all unnumbered interfaces will be considered as having no SRLG membership if the
user enabled the user-srlg-db option.
This feature also extends the support of lsp-ping, p2mp-lsp-ping, lsp-trace, and p2mp-lsptrace to
P2P and P2MP LSPs that have unnumbered TE links in their path.
Operation of RSVP FRR Facility Backup over Unnumbered Interface
When the Point-of-Local Repair (PLR) node activates the bypass LSP by sending a PATH
message to refresh the path state of protected LSP at the Merge-Point (MP) node, it must use an
IPv4 tunnel sender address in the sender template object that is different than the one used by the
ingress LER in the PATH message. These are the procedures specified in RFC 4090 and that are
followed in the 7x50 implementation.
The 7x50 uses the address of the outgoing interface of the bypass LSP as the IPv4 tunnel sender
address in the sender template object. This address will be different from the system interface
address used in the sender template of the protected LSP by the ingress LER and thus there are no
conflicts when the ingress LER acts as a PLR.
When the PLR is the ingress LER node and the outgoing interface of the bypass LSP is
unnumbered, it is required that the user assigns to the interface a borrowed IP address that is
different from the system interface. If not, the bypass LSP will not come up.
In addition, the PLR node will include the IPv4 RSVP_HOP object (C-Type=1) or the IF_ID
RSVP_HOP object (C-Type=3) in the PATH message if the outgoing interface of the bypass LSP
is numbered or unnumbered respectively.