Configuration Guide - IP Unicast Routing

Procedure

1. Configure the IS-IS cost style.
   1. Run:

      system-view

      The system view is displayed.

   2. Run:

      isis [ process-id ]

      The IS-IS view is displayed.

   3. Run:

      cost-style { narrow | wide | wide-compatible | { narrow-compatible | compatible } [ relax-spf-limit ] }

      The IS-IS cost style is configured.

      By default, the cost style of routes received and sent by an IS-IS device is narrow.

   The cost range of an interface and a route received by the interface vary with the cost type.

   • If the cost style is narrow, the cost of an interface ranges from 1 to 63. The maximum cost of a route received by the interface is 1023.

   • If the cost style is narrow-compatible or compatible, the cost of an interface ranges from 1 to 63. The cost of a received route is related to relax-spf-limit.

   • If the cost style is wide-compatible or wide, the cost of the interface ranges from 1 to 16777215. When the cost is 16777215, the neighbor TLV generated on the link cannot be used for route calculation but for the transmission of TE information. The maximum cost of a received route is 0xFFFFFFFF.

2. Configure the cost of an IS-IS interface.

   Perform any of the following operations to configure the cost of an IS-IS interface.

   Configure the cost of a specified IS-IS interface.
   1. Run:

      system-view

      The system view is displayed.

   2. Run:

      interface interface-type interface-number

      The interface view is displayed.

   3. (Optional) On an Ethernet interface, run undo portswitch

      The interface is switched to Layer 3 mode.

      By default, an Ethernet interface works in Layer 2 mode.

   4. Run:

      isis cost { cost | maximum } [ level-1 | level-2 ]

      The cost of the IS-IS interface is configured.

      By default, the link cost of an IS-IS interface is 10.

      NOTE:

      You can configure the parameter maximum only when the IS-IS cost style is wide or wide-compatible.

      To change the cost of a loopback interface, run the isis cost command only in the loopback interface view.

   Configure the global IS-IS cost.

   1. Run:

      system-view

      The system view is displayed.

   2. Run:

      isis [ process-id ]

      The IS-IS view is displayed.

   3. Run:

      circuit-cost { cost | maximum } [ level-1 | level-2 ]

      The global IS-IS cost is configured.

      By default, no global cost is configured.

   Enable IS-IS to automatically calculate the interface cost.

   1. Run:

      system-view

      The system view is displayed.

   2. Run:

      isis [ process-id ]

      The IS-IS view is displayed.

   3. Run:

      bandwidth-reference value

      The reference value of the bandwidth is configured. By default, the bandwidth reference value is 100 Mbit/s.

   4. Run:

      auto-cost enable [ compatible ]

      The interface is configured to automatically calculate its cost.

   The bandwidth reference value set using the bandwidth-reference command takes effect only when the cost style is wide or wide-compatible. In this case, the interface cost is calculated using the following formula:

   Cost of each interface = (Bandwidth-reference/Interface bandwidth) × 10

   If the cost-style is narrow, narrow-compatible, or compatible, the cost of each interface is calculated based on costs listed in Table 7-11.

   Table 7-11  Mapping between IS-IS interface costs and interface bandwidth

   Cost	Bandwidth Range
   60	Interface bandwidth ≤ 10 Mbit/s
   50	10 Mbit/s < Interface bandwidth ≤ 100 Mbit/s
   40	100 Mbit/s < Interface bandwidth ≤ 155 Mbit/s
   30	155 Mbit/s < Interface bandwidth ≤ 622 Mbit/s
   20	622 Mbit/s < Interface bandwidth ≤ 2.5 Gbit/s
   10	2.5 Gbit/s < Interface bandwidth