Cluster Networking Quirks

Introduction

This is a wiki page detailing weird network quirks the lab has encountered over the years.

List of events

• May 5, 2025

  Vav and Gimel (both are in the 169.230.26.0 subnet) had a problem contacting the 169.230.75.0 subnet.
  Both of these machines had similar ip route rules, displayed below.
  
  #vav
  169.230.0.0/16 dev enp4s0 proto kernel scope link src 169.230.26.169 metric 100
  #gimel
  169.230.0.0/16 dev eth4  proto kernel  scope link  src 169.230.26.166
  
  The rules above tell us that any IP addresses in this range 169.230.1.0 ~ 169.230.255.254 should be visible but they weren't.
  
  But for some reason, if I narrow down the subnet to 255.255.255.0 then we're able to ping the 169.230.75.0 subnet. So here are the new rules that allow connection to happen.
  
  #vav
  169.230.26.0/24 dev enp4s0 proto kernel scope link src 169.230.26.169 metric 100
  #gimel
  169.230.26.0/24 dev eth4  proto kernel  scope link  src 169.230.26.166