BGPv4 Filter Configuration Delimiter Change for AS-PATH Prepending

Products

• VMware SD-WAN by VeloCloud

Issue/Introduction

This KB article documents an issue seen when AS-PATH prepending is configured using comma delimiters previous to an upgrade to 4,0,0 or newer, or when the comma delimiters are used in a 4.0.0 or newer release.

The issue is being tracked separately for UI and API, with ticket ID #52952 and #53208 respectively.

Release Notes 4.0.0, 4.0.1, 4.0.2, 4.2.0, 4.2.1, 4.3.0, and 4.4.0 have all been updated to reference this under the "Important Notes" section of the document.

Symptoms:

Through Release 3.X, the VMware SD-WAN BGPv4 filter configuration for AS-PATH prepending supported both comma and space-based delimiters. However, beginning in Release 4.0.0 and forward, VMware SD-WAN will only support a space-based delimiter in an AS-Path prepending configuration, leading to a failure to apply the BGP settings correctly when the comma delimiter is in use.

Supported configuration in all releases:

Supported only on 3.X and older releases:

Environment

VMware SD-WAN by VeloCloud

Cause

Due to changes performed in the routing system of the VMware SD-WAN Edge, releases 4.X and newer, the comma delimiter stopped being a valid separator for AS-PATH prepending.

Resolution

Validation will be implemented in the VMware SD-WAN Orchestrator to let the users know the configuration is not supported when trying to use comma-separated values, the change will be implemented starting 5.X

Workaround:
Customers upgrading from 3.X to 4.X need to edit their AS-PATH prepending configurations to replace commas with spaces prior to upgrade to avoid incorrect BGP best route selection.

New configurations or filters need to also be created using space delimiters instead of comma delimiters.