3V0-25.25: Advanced VMware Cloud Foundation 9.0 Networking

By Broadcom · Question Mode

QuestionQ18

VerifiedUnknown / not found in official Broadcom sources

An administrator is troubleshooting an issue in which workloads connected to a Tier-1 Gateway named T1-App can no longer reach external North/South destinations.

The Tier-1 connects to an Active/Standby Tier-0 Gateway named T0-Prod.

Observed symptoms:

  • VMs on segments attached to T1-App can ping one another.
  • VMs on T1-App cannot reach any external IP beyond T0-Prod.
  • From a VM on the segment, a ping to the T1-App Distributed Router (DR) IP succeeds.
  • A ping from the VM to the T1-App Service Router (SR) fails.
  • The Edge cluster hosting the T1-App SR reports both Edge nodes as Up and Healthy.
  • No failover has occurred; the same Edge node is still displayed as Active for T1-App.

What is the most likely cause of this issue?

Explanation

A Tier-1 gateway’s distributed router provides distributed segment routing, while its service router runs on an Edge node for centralized routing and services. Traffic leaving the Tier-1 must traverse the overlay transit path between those components. An MTU mismatch on that encapsulated path can break connectivity to the service router even while the DR, local segment traffic, and Edge-node health remain operational. Route advertisement and default-route problems occur after the service-router hop and do not prevent reaching the Tier-1 SR itself.

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