Example: Configuring Is-Is Frr; Network Requirements; Requirements Analysis; Software Version Used - H3C S12500 Configuration Examples

Example: Configuring IS-IS FRR

Network requirements

As shown in
domain.
Configure IS-IS FRR to make sure when Link A fails, traffic will be switched to Link B immediately.
Figure 3 Network diagram

Requirements analysis

To make sure Link B is a backup for Link A, configure a greater cost for Link B.
To make sure Switch S can immediately detect failures on the link between Switch S and Switch A,
enable BFD on Switch S.
To make sure Link B takes effect immediately when Link A fails, enable FRR on Switch S by using the
fast-reroute auto command or by using a routing policy. When you enable IS-IS FRR to designate a
backup next hop by using a routing policy:
• To allow only matching packets to be switched to the backup link, specify an IP prefix list.
To configure the backup route for link switchover, specify both the output interface and next hop
•
of the route in the routing policy.

Software version used

This configuration example was created and verified on S12500-CMW520-R1825P01.

Configuration restrictions and guidelines

When you configure IS-IS FRR, follow these restrictions and guidelines:
Do not use IS-IS FRR and IS-IS BFD at the same time.
•
Figure 3, Switch S, Switch A, Switch B, and Switch D belong to the same IS-IS routing
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