Configure keychains for IS-IS

Updated: September 8, 2026

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Guides you through configuring keychains for IS-IS to secure protocol communications, including authentication setup for router and interface levels using keychains for LSPs, Sequence Number PDUs, and HELLO PDUs.

Secure IS-IS protocol messages by configuring keychains at both router and interface levels.

Keychains are used in IS-IS to authenticate Link State PDUs (LSPs) and HELLO PDUs. Configuring keychains enhances protocol security and enables verification of network communication integrity.

Before you begin

Identify the keychain names and authentication keys for your IS-IS deployment.
Ensure you are in global configuration mode on the device.

Procedure

Enter IS-IS router configuration mode, and configure the router-level keychain for IS-IS LSPs and Sequence Number PDUs.
Example:
```
Router(config)# router isis isp
Router(config-isis)# lsp-password keychain isis_a level 1
```
Enter interface configuration mode for the IS-IS-enabled interface, and configure the interface-level keychain for HELLO PDUs.
Example:
```
Router(config-isis)# interface HundredGigE 0/1/0/3
Router(config-isis-if)# hello-password keychain isis_b
```

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Configure keychains for IS-IS

Before you begin

Procedure

Example:

Example: