Maximum IPv4 prefixes received from BGP neighbor is approaching alarm

Products

• VMware NSX

Issue/Introduction

Title: Alarm for maximum IPv4 prefixes received from BGP neighbor is approaching.

Event ID: maximum_ipv4_prefixes_from_bgp_neighbor_approaching.

Alarm Description:

• Purpose: This alarm is used to notify the user that the maximum IPv4 prefixes received from BGP neighbor is about to be reached.
• Impact: There is no functional impact. This alarm is to notify the user that the maximum number of routes received from BGP neighbor is approaching. This scenario can mean higher CPU usage by the BGP process.

Environment

VMware NSX

Cause

This alarm is used to notify the user that the maximum IPv4 prefixes received from BGP neighbor is about to be reached.

Resolution

Steps to Resolve

For 4.0.1.1 and higher

 

Recommended Action: 

1. BGP is an exterior gateway protocol and it is utilized for the propagation of routing information that traffic is dependent on, care must be taken to ensure excessively large routing tables are not on the Edge device.
2. If the routing table is too large, CPU consumption on the Edge can increase and this can lead to CPU starvation across all other processes in the Edge node.
3. Since the Edge Node also serves as a virtual router, it can also lead to traffic drop.
4. If the requirement of the user has changed to support more routes then the configuration on the UI needs to be updated.
5. If the increase in the number of routes is not expected then user need to check what is the increase in the number of routes learned from the BGP neighbor.
6. One can also check the BGP neighbor configuration to confirm if any new redistribute configuration or new import export policy is changed or if any route map configuration is changed to permit new routes.
7. If some routes can be filtered then necessary actions need to be taken by configuring the deny policy for unwanted routes [See NSX Documentation - Create a Route Map].

Maintenance window required for remediation? No

There is no functional impact. This scenario can mean higher CPU usage by the BGP process.