H3C Technologies H3C S10500 Series Switches - Manual (Page 127)

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FRR uses bypass tunnels to protect primary tunnels. As bypass tunnels are pre-established, they require
extra bandwidth and are usually used to protect crucial interfaces or links only.
You can define which type of LSP can use bypass LSPs, and whether a bypass LSP provides bandwidth
protection as well as the sum of protected bandwidth.
The bandwidth of a bypass LSP is to protect its primary LSPs. To guarantee that a primary LSP can always
bind with the bypass LSP successfully, make sure that the bandwidth assigned to the bypass LSP is not less
than the total bandwidth needed by all protected LSPs.
Normally, bypass tunnels only forward data traffic when protected primary tunnels fail. To allow a
bypass tunnel to forward data traffic while protecting the primary tunnel, you must ensure that bypass
tunnels are available with adequate bandwidth.
A bypass tunnel cannot be used for services like VPN at the same time.
Configuration prerequisites
Before you configure FRR, complete the following tasks:
• Configure IGP, ensuring that all LSRs are reachable
• Configure basic MPLS
• Configure basic MPLS TE
• Establish an MPLS TE tunnel with RSVP-TE
• Set up primary LSPs
Configuration procedure
Enabling FRR on the headend of a primary LSP
Follow these steps to enable FRR on the headend of a primary LSP:
To do… Use the command... Remarks
Enter system view system-view ––
Enter tunnel interface view of the
primary LSP
interface tunnel tunnel-number ––
Enable FRR mpls te fast-reroute
Required
Disabled by default
Submit current tunnel configuration mpls te commit Required
Configuring a bypass tunnel on its PLR
After a tunnel is specified to protect an interface, its corresponding LSP becomes a bypass LSP. The setup
of a bypass LSP must be manually performed on the PLR. The configuration of a bypass LSP is similar to
that of a common LSP, but a bypass LSP cannot act as a primary LSP to be protected by another LSP at
the same time.
When specifying a bypass tunnel for an interface, ensure the following:
• The bypass tunnel is up.
• The protected interface is not the outgoing interface of the bypass tunnel.
Up to three bypass tunnels can be specified for a protected interface. The best-fit algorithm is used to
determine which of them is used in case failure occurs.