Enterprise SONiC: BGP Session Does Not Come Up When Local-AS Precedes Peer-Group Configuration

Summary: Enterprise SONiC Distribution by Dell Technologies. In Free Range Routing (FRR), the local-as command is used to override the router’s global BGP Autonomous System (AS) number for a specific neighbor, enabling flexible AS configurations without changing the global AS. However, if local-as is applied before the peer-group or remote-as association, the BGP session fails to establish. This is due to FRR’s strict command dependency order, which requires the peer-group or remote-as to be configured first. ...

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Symptoms

Issue:
When local-as is configured under a BGP neighbor before applying the peer-group (which contains the remote-as), FRR throws the following error:
 

ERR bgp#frrcfgd: % Error: Specify remote-as or peer-group commands first


As a result, the BGP session remains down.

Cause

Root Cause:
FRR enforces a configuration hierarchy where the remote-as or peer-group association must be applied before local-as. Applying local-as directly under the neighbor without prior peer-group linkage violates this requirement.

Resolution

Resolution Steps:
  1. Remove incorrect local-as configuration:
  2. Apply local-as under the peer-group:
  3. Clear the BGP session to apply changes:

Best Practice:
  • Always configure remote-as or apply the peer-group before adding local-as.
  • Apply local-as at the peer-group level for consistency and simplified management
Article Properties
Article Number: 000395876
Article Type: Solution
Last Modified: 28 كانون الثاني 2026
Version:  2
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