Configuring LDP FRR
By configuring LDP FRR, you can quickly switch traffic to the backup LSP when a link fails, which ensures uninterrupted traffic transmission.
Pre-configuration Tasks
There are two types of LDP FRR: manual LDP FRR and Auto LDP FRR. Configure LDP FRR by perform either of the following pre-configuration tasks as required.
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Before configuring manual LDP FRR, complete the following tasks:
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Configuring a local LDP session according to Configuring Basic Functions of MPLS LDP
Configuring single-hop BFD if BFD-based LDP FRR needs to be configured (see BFD Configuration in Huawei AR Series Access Routers Configuration Guide - Reliability)
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Before configuring Auto LDP FRR, complete the following tasks:
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Configuring a local LDP session according to Configuring Basic Functions of MPLS LDP
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Configuring Auto IGP FRR (see Huawei AR Series Access Routers Configuration Guide - IP Routing)
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To implement millisecond-level switching, perform Configuring Static BFD to Detect an LDP LSP or Configuring Dynamic BFD for LDP LSPs.
Context
Manual LDP FRR: A backup LSP is configured manually by specifying an outbound interface or a next hop. The configuration is complex and flexible. Manual LDP FRR applies to simple networks.
Auto LDP FRR: A backup LSP is automatically created based on a specified policy. The configuration is simple and prevents loops. Auto LDP FRR applies to complex and large networks.
Perform the following steps on the ingress or transit node:
Procedure
- Configuring manual
LDP FRR
- Run mpls ldp frr nexthop nexthop-address [ ip-prefix ip-prefix-name ] [ priority priority ]
LDP FRR is enabled on the interface.
By default, no interface is enabled with LDP FRR.
On the same interface, you can configure up to 10 LDP FRR entries with different precedences. According to different precedences, only one bypass LSP is generated. The smaller the value is, the higher the precedence is. By default, the precedence value is 50.
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LDP FRR cannot be enabled or disabled during the LDP GR.
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If manual LDP FRR and IP FRR are deployed concurrently, IP FRR is used preferentially.
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When the undo mpls ldp command is run to disable the LDP function in the system view or the undo mpls ldp command is run to disable the LDP function in the interface view, the LDP FRR configuration in the interface view is not automatically deleted. Only the LDP FRR function is invalid.
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In manual LDP FRR configuration, the backup LSP must be in liberal state. That is, the route state of the bypass LSP from Ingress to Egress node must be "Inactive Adv".
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- Run mpls ldp frr nexthop nexthop-address [ ip-prefix ip-prefix-name ] [ priority priority ]
- Configuring Auto LDP FRR
- Run auto-frr lsp-trigger { all | host | ip-prefix ip-prefix-name | none }
A policy for triggering backup LDP LSP establishment is configured.
By default, LDP uses backup routes to addresses with 32-bit masks to set up backup LSPs.
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During the LDP GR process, a policy for triggering the backup LDP LSP establishment cannot be changed.
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Auto LDP FRR depends on IGP auto FRR. After the frr (IS-IS) or frr (OSPF) command is used to enable IGP auto FRR, Auto LDP FRR will be automatically enabled. The auto-frr lsp-trigger command is used to configure or change a policy for triggering backup LDP LSP establishment.
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If both the auto-frr lsp-trigger command and the lsp-trigger command are run, the established backup LSPs satisfy both the policy for triggering LDP LSP establishment and the policy for triggering backup LDP LSP establishment.
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- Run auto-frr lsp-trigger { all | host | ip-prefix ip-prefix-name | none }