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CLNS Configuration Overview


To configure CLNS:

  1. Configure the network interfaces. See the Junos OS Interfaces Configuration Guide for Security Devices.
  2. If applicable, configure BGP and VPNs. See:
  3. Configure a VPN routing instance. You typically configure ES-IS, IS-IS, and CLNS static routes using a VPN routing instance. See Example: Configuring a VPN Routing Instance for CLNS.
  4. Configure one or more of the following protocols for CLNS (depending on your network).

    • ES-IS—If a device is a PE router within a CLNS island that contains any end systems, you must configure ES-IS on the device. If a CLNS island does not contain any end systems, you do not need to configure ES-IS on a device. See Example: Configuring ES-IS for CLNS.


      ES-IS is enabled only if either ES-IS or IS-IS is configured on the router. ES-IS must not be disabled. If ES-IS is not explicitly configured, the interface sends and receives only intermediate system hello (ISH) messages. If ES-IS is explicitly configured and disabled, the interface does not send or receive ES-IS packets. If ES-IS is explicitly configured and not disabled, the interface sends and receives ISH messages as well as ES-IS packets.

      One of the interfaces that is configured for ES-IS must be configured with an ISO address for hello messages. The ISO address family must be configured on an interface to support ES-IS on that interface.

    • IS-IS—You can configure IS-IS to exchange CLNS routes within a CLNS island. See Example: Configuring IS-IS for CLNS.


      If you have a pure CLNS island—an island that does not contain any IP devices—you must disable IPv4 and IPv6 routing. Also, to export BGP routes into IS-IS, you must configure and apply an export policy.

    • Static routes—If some devices in your network do not support IS-IS, you must configure CLNS static routes. You can use static routing with or without IS-IS. You might also consider using static routes if your network is simple. See Example: Configuring Static Routes for CLNS When No IGP is Present.

    • BGP—See Example: Configuring BGP for CLNS VPNs.


Many of the configuration statements used to configure CLNS and routing protocols can be included at different hierarchy levels in the configuration.