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Configuring tunnel policies
Overview
Tunnel policies enable a PE to forward traffic for each MPLS VPN over a preferred tunnel or over
multiple tunnels. The tunnels supported by MPLS VPN include MPLS LSPs, MPLS TE tunnels, and
GRE tunnels.
To enhance availability, you can associate multiple MPLS TE tunnels to a tunnel bundle, and specify
the tunnel bundle as a preferred tunnel.
For more information about MPLS TE, see
see Layer 3—IP Services Configuration Guide. For more information about MPLS VPNs, see
"Configuring MPLS
information about tunnel bundles, see
switching."
Configuring a tunnel policy
Configuration guidelines
When you configure a tunnel policy, follow these guidelines:
•
To select a preferred tunnel, create a tunnel policy and specify the preferred tunnel with the
preferred-path command. The destination address of the preferred tunnel identifies a peer PE
so the PE will forward traffic destined for that peer PE over the preferred tunnel.
If you specify multiple preferred tunnels that have the same destination address in a tunnel
policy, only the first configured tunnel takes effect.
If the first tunnel is not available, the second tunnel is used, and so forth. No load balancing
will be performed on these tunnels.
This method explicitly specifies an MPLS TE tunnel, GRE tunnel, or tunnel bundle for an MPLS
VPN, facilitating traffic planning. As a best practice, use this method.
•
To select multiple tunnels for load sharing, create a tunnel policy and specify the tunnel
selection order and the number of tunnels by using the select-seq load-balance-number
command. A tunnel type closer to the select-seq keyword has a higher priority. For example,
the select-seq lsp gre load-balance-number 3 command gives LSP higher priority over GRE.
If no LSP is available or the number of LSPs is less than 3, VPN uses GRE tunnels. The tunnels
selected by this method are not fixed, complicating traffic planning. As a best practice, do not
use this method.
If you configure both methods for a tunnel policy, the tunnel policy selects tunnels in the following
steps:
1.
If the destination address of a preferred tunnel identifies a peer PE, the tunnel policy uses the
preferred tunnel to forward traffic destined for the peer PE.
2.
If not, the tunnel policy selects tunnels as configured by the select-seq load-balance-number
command.
"Configuring MPLS
L3VPN,"
"Configuring MPLS
"Configuring MPLS
182
TE." For more information about GRE,
L2VPN," and
"Configuring
TE," and
"Configuring MPLS protection
VPLS." For more
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