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Cisco Bug: CSCvs90520 - Cisco-IOS-XE-bgp: Unable to detect 4-Byte vs 2-byte ASN format

Last Modified

Sep 01, 2020

Products (1)

  • Cisco IOS

Known Affected Releases


Description (partial)

BGP model get-config and show-running are our of sync when 4-byte ASN and 2-byte ASN formats are used interchangeably.

The show-running will display one format, while the get-config returns the other format. If the configuration is deleted from the CLI, it may not be deleted from CDB.

Case 1: If ASN is configured in 2-byte ASN format, but "bgp asnotation dot" is configured, the show-running and get-config will display different values.

For example - 
CSR-uut#config t
Enter configuration commands, one per line.  End with CNTL/Z.
CSR-uut(config)#no router bgp 100
CSR-uut(config)#router bgp 65538 
CSR-uut(config-router)#bgp asnotation dot 
CSR-uut#show run | sec bgp
router bgp 1.2
 bgp asnotation dot
 bgp log-neighbor-changes

The show-running returns "1.2", while the get-config will returned the parsed value of 65538.

Case 2: If the configuration is deleted from IOS CLI in a different format from what is stored in the model, the configuration does not get deleted from the model.

For example - 
The customer configures via netconf - "router bgp 65538" and "bgp asnotation dot". Get-config will return the configured value of "65538", while the show-running will display the as-dot notation value "1.2".

Now, if the customer does "no router bgp 1.2" from the IOS CLI, bgp will be deleted from the device, but not the model. A get-config will still return "router bgp 65538".
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