Spanning TreeMST Config

revision [number]

Sets the revision number for the MST configuration, which is used to identify the MST region and must match on all switches in the same region.

Syntax·MST Config

revision [number]

When to Use This Command

Configuring a consistent revision number across all switches in an MST region to ensure they recognize each other as part of the same region.
Changing the revision number when modifying the MST configuration to force a new region identifier.
Setting the revision number to a non-zero value to avoid conflicts with the default revision of 0.
Troubleshooting MST region mismatches by verifying and aligning revision numbers.

Command Examples

Setting MST revision number to 1

revision 1

No output is generated for this command. It simply sets the revision number to 1 in the MST configuration context.

Verifying MST configuration after setting revision

show current

Current MST configuration:
Name      []
Revision  1
Instance  Vlans mapped
--------  -----------------------------------------------------------------
0         1-4094

The output shows the current MST configuration. 'Revision 1' confirms the revision number was set to 1. The instance mapping shows VLANs 1-4094 are mapped to instance 0 by default.

Understanding the Output

The 'revision' command itself produces no output. To verify the revision number, use 'show current' or 'show pending' in MST configuration mode. The revision number is displayed as 'Revision <number>'. It must match on all switches in the same MST region. A mismatch will prevent switches from forming a single region, causing them to treat each other as separate regions (CST). The default revision is 0, which is commonly used but can be changed to any integer. Ensure consistency across all switches in the region.

CCNA Exam Tips

Remember that the revision number must match on all switches in the same MST region; otherwise, they will not form a single region.

The default revision number is 0; changing it to a non-zero value can help avoid accidental region mismatches.

CCNA exam may test that MST region configuration requires matching name, revision, and VLAN-to-instance mapping.

Be aware that 'revision' is configured in MST configuration mode, not global config.

Common Mistakes

Setting different revision numbers on switches that should be in the same MST region, causing region mismatch.

Forgetting to apply the configuration with 'exit' or 'apply' after setting the revision number.

Using the 'revision' command in global configuration mode instead of MST configuration mode.

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