Configuring VLAN Interface Metrics
Normally, IS-IS metrics can have values up to 63. These metrics are
narrow metrics. IS-IS generates two type, length, and value (TLV) codings, one for an IS-IS
adjacency (code, length, and value (TLV) 2) and the second for an IP prefix (TLV 128 and TLV
130). During SPF, if the total cost of the path to a destination exceeds 1023, then
according to ISO/IEC 10587, the path is ignored.
To overcome these restrictions, a second pair
of TLVs is available, one for IP prefixes (TLV 135) and the second
for IS-IS adjacency (TLV 22). With these TLVs, IS-IS metrics can
have values up 16,777,215 and the maximum path metric allowed is
4,261,412,864. This allows more flexibility while designing a domain.
These metrics are wide metrics.
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To configure the metric style used on the router, use the
following command:
configure
isis area area_name metric-style [[narrow | wide] {transition}] | transition] {level [1 | 2]}
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To configure the narrow metric used on one or all
interfaces, use the following command:
configure
isis [vlan all | {vlan} vlan_name] metric metric {level[1|2]}
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To configure the wide metric used on one or all
interfaces, use the following command:
configure
isis [vlan all | {vlan} vlan_name] wide-metric metric {level[1 | 2]}

Note
Configured narrow and wide metrics for a
particular interface must be identical in value while migrating from metric style narrow
to metric style wide. Only if the metric style is “narrow” or “wide” (that is, no
“transition”) is it okay to have different values (because one of the values is not
used).