9. ISIS default route

1. ISIS default route

1. In IS-IS, the generation and advertisement of default routes are mainly controlled through the following three methods.

1. On the Level-1-2 device, control the setting of the ATT bit in the Level-1 LSP generated by it.
2. On the Level-1 device, configure it so that it will not automatically generate a default route even if it receives a Level-1 LSP with the ATT bit set.
3. Advertise the default route in IS-IS.

1. How to configure default route generation

1. (Level-1-2 equipment) Set the ATT bit bit setting rule for IS-IS LSP packets.

[Huawei-isis-1] attached-bit advertise { always | never } // Only configured on L1-2

1. (Level-1 device) Control the Level-1 device not to deliver the default route to the routing table because of the ATT bit.

[Huawei-isis-1] attached-bit avoid-learning //To be configured on both L1-2 and L-1

1. Configuring Devices Running IS-IS to Generate Default Routes

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