Path Option And Path Protection; Auto-Tunnel Mesh - Cisco CRS Configuration Manual

Auto-Tunnel Mesh

Related Topics
Configuring Attributes within a Path-Option Attribute, on page 322

Path Option and Path Protection

When path-protection is enabled, a standby LSP is established to protect traffic going over the tunnel. The
standby LSP may be established using either the same path option as the primary LSP, or a different one.
The standby LSP is computed to be diverse from the primary LSP, so bandwidth class differences does not
matter. This is true in all cases of diversity except node-diversity. With node diversity, it is possible for the
standby LSP to share up to two links with the primary LSP, the link exiting the head node, and the link entering
the tail node.
If you want to switchover from one path option to another path option and these path options have different
classes, the path option switchover is rejected. However, the path option switchover can not be blocked in the
path-protection feature. When the standby LSP becomes active using another path option of a different class
type, the path option switchover cannot be rejected at the head end. It might get rejected by the downstream
node.
Node-diversity is only possible under limited conditions. The conditions that must be met are:
• there is no second path that is both node and link diverse
• the current LSP uses a shared-media link at the head egress or tail ingress
• the shared-media link used by the current LSP permits computation of a node-diverse path
In Cisco IOS XR, reoptimization between different class types would actually be rejected by the next hop.
This rejection will occur by an admission failure.
Related Topics
Configuring Attributes within a Path-Option Attribute, on page 322
Auto-Tunnel Mesh
The MPLS traffic engineering auto-tunnel mesh (Auto-mesh) feature allows you to set up full mesh of TE
P2P tunnels automatically with a minimal set of MPLS traffic engineering configurations. You may configure
one or more mesh-groups. Each mesh-group requires a destination-list (IPv4 prefix-list) listing destinations,
which are used as destinations for creating tunnels for that mesh-group.
You may configure MPLS TE auto-mesh type attribute-sets (templates) and associate them to mesh-groups.
LSR creates tunnels using the tunnel properties defined in the attribute-set.
Auto-Tunnel mesh provides benefits:
• Minimizes the initial configuration of the network.
• Minimizes future configurations resulting due to network growth.
Cisco IOS XR MPLS Configuration Guide for the Cisco CRS Router, Release 5.1.x
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You may configure tunnel properties template and mesh-groups or destination-lists on each TE LSRs
that further creates full mesh of TE tunnels between those LSRs.
It eliminates the need to reconfigure each existing TE LSR in order to establish a full mesh of TE tunnels
whenever a new TE LSR is added in the network.
Implementing MPLS Traffic Engineering