Interface metrics are available in two sizes: a 6-bit narrow metric and a 24-bit wide metric. By default only narrow metrics are used. Wide metrics allow for greater flexibility, however, and are required in order to use some extensions of IS-IS, such as IPv6. All routers in an IS-IS area must use the same metric style.
For instructions on configuring interface metric style and values, see Configuring VLAN Interface Metrics. Refer to RFC 3787, Section 5.1, for migration details. Note that the ExtremeXOS software does not support section 5.2.