Maximum IPv4 routes limit is approaching on Edge node alarm

Products

• VMware NSX

Issue/Introduction

Title: Alarm for maximum IPv4 routes limit is approaching on Edge node.

Event ID: routing.maximum_ipv4_route_limit_approaching.

 

Alarm Description:

• Purpose: This alarm is used to notify the user that the maximum IPv4 prefix limit is about to reach.
• Impact: There is no functional impact. This alarm is for users who wish to monitor the number of routes to be handled by the edge node. This scenario can mean higher CPU usage.

Environment

VMware NSX

Resolution

Steps to Resolve

For 4.0.1.1 and higher

 

Recommended Action: 

1. As of now, in NSX, the route limit is fixed across all Edge Node form factors and it is not configurable. To correct this issue, the NSX deployment needs to be designed in such a way that the limits are adhered to. This alarm is raised when 75% of the max IPv4 route limit is reached. 
   1. RIB_PREFIX_COUNT_IPV4_MAX 500000
   2. RIB_PREFIX_COUNT_IPV6_MAX 100000
2. If the increase in the number of routes is not expected then one can verify the number of routes that are dynamically learned across all the routing protocols and the static routes that are configured.
3. Once it is clear from which protocol the routes are learned, the user needs to check the neighboring router configuration to see if any new redistribution has been enabled recently and if the change is intentional.
4. 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