Mpls Facility Bypass Method Of Mpls Fast Re-Route (Frr); Manual Bypass Lsp - Alcatel-Lucent 7450 Manual

MPLS Facility Bypass Method of MPLS Fast Re-Route (FRR)

The MPLS facility bypass method of MPLS Fast Re-Route (FRR) functionality is extended to the
ingress node.
The behavior of an LSP at an ingress LER with both fast reroute and a standby LSP path
configured is as follows:
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Manual Bypass LSP

In prior releases, the router implemented dynamic bypass tunnels as per RFC 4090, Fast Reroute
Extensions to RSVP-TE for LSP Tunnels. When an LSP is signaled and the local protection flag is
set in the session_attribute object and/or the FRR object in the path message indicates that facility
backup is desired, the PLR will establish a bypass tunnel to provide node and link protection. If a
bypass LSP which merges in a downstream node with the protected LSP exist, and if this LSP
satisfies the constraints in the FRR object, then this bypass tunnel is selected.
With the manual bypass feature, an LSP can be pre-configured from a PLR which will be used
exclusively for bypass protection. When a path message for a new LSP requests bypass protection,
the node will first check if a manual bypass tunnel satisfying the path constraints exists. If one is
found, it will be selected. If no manual bypass tunnel is found, the router will dynamically signal a
bypass LSP in the default behavior. Users can disable the dynamic bypass creation on a per node
basis using the CLI.
A maximum of 1000 associations of primary LSP paths can be made with a single manual bypass
by default. The max-bypass-associations integer command increases the number of associations.
7450 ESS MPLS Guide
When a down stream detour becomes active at a point of local repair (PLR):
The ingress LER switches to the standby LSP path. If the primary LSP path is repaired
subsequently at the PLR, the LSP will switch back to the primary path. If the standby goes
down, the LSP is switched back to the primary, even though it is still on the detour at the
PLR. If the primary goes down at the ingress while the LSP is on the standby, the detour at
the ingress is cleaned up and for one-to-one detours a "path tear" is sent for the detour
path. In other words, the detour at the ingress does not protect the standby. If and when the
primary LSP is again successfully re-signaled, the ingress detour state machine will be
restarted.
When the primary fails at the ingress:
The LSP switches to the detour path. If a standby is available then LSP would switch to
standby on expiration of hold-timer. If hold-timer is disabled then switchover to standby
would happen immediately. On successful global revert of primary path, the LSP would
switch back to the primary path.
Admin groups are not taken into account when creating detours for LSPs.
MPLS and RSVP
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