Nokia 7705 SAR-W Series Manual page 87

MPLS Guide
To support unnumbered TE links in RSVP-TE, a new sub-object of the Explicit Route
Object (ERO) is added to specify unnumbered links and a new sub-object of the
Route Record Object (RRO) is added to record that the LSP traversed an
unnumbered link, as per RFC 3477, Signalling Unnumbered Links in Resource
ReSerVation Protocol - Traffic Engineering (RSVP-TE). As well, a new IF_ID
RSVP_HOP object with a C-Type of 3 is added as per section 8.1.1 of RFC 3473,
Generalized Multi-Protocol Label Switching (GMPLS) Signaling Resource
ReserVation Protocol-Traffic Engineering (RSVP-TE) Extensions. The IPv4 Next/
Previous Hop Address field in the object is set to the borrowed IP interface address.
The unnumbered IP interface address is advertised by IS-IS-TE or OSPF-TE, and
CSPF can include it in the computation of a path for a point-to-point LSP. However,
this feature does not support defining an unnumbered interface as a hop in the path
definition of an LSP.
A router creates an RSVP neighbor over an unnumbered interface using the tuple
(router ID, ifindex). The router ID of the router that advertised an unnumbered
interface index is obtained from the TE database. Therefore, if traffic engineering is
disabled in IS-IS or OSPF, a non-CSPF LSP that has its next hop over an
unnumbered interface will not come up at the ingress LER because the router ID of
the neighbor that has the next hop of the PATH message cannot be looked up. The
LSP path will remain operationally down with the error "noRouteToDestination". If a
PATH message is received at the LSR for which traffic engineering was disabled and
the next hop for the LSP is over an unnumbered interface, a PathErr message is sent
back to the ingress LER with the error code of 24 "Routing Problem" and an error
value of 5 "No route available toward destination".
All MPLS (RSVP-TE and LDP) features supported for numbered IP interfaces are
supported for unnumbered interfaces, with the following exceptions:
The unnumbered interface feature also extends the support of LSP ping and LSP
traceroute to point-to-point LSPs that have unnumbered TE links in their path.
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• configuration of a router ID with a value other than system interface
• signaling of an LSP with an ERO based on a loose or strict hop using an
unnumbered TE link in the path hop definition
• signaling of a one-to-one detour LSP over an unnumbered interface
• RSVP Hello messages and all Hello-related capabilities, such as Graceful-
Restart Helper
• RSVP refresh reduction on an unnumbered interface
Use subject to Terms available at: www.nokia.com
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MPLS and RSVP-TE
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