I have a Brocade FastIron FESX648 and I'm attempting to increase the ARP cache timeout on a port that is connected to an IXP. According to the Brocade docs, I can increase the timeout up to 4 hours with the setting ip arp-age 240.

I've tried applying this setting globally, specifically to the IXP-facing port and variety of other combinations (lower and higher timeout values), but nothing seems to work. Whenever I run show arp I can see that the ARP entries for IXP hosts are continually refreshed and never age higher than 4 minutes.

Has anyone faced a similar problem with Brocade FastIron gear and have any config suggestions or possible workarounds?

  • Not sure about Brocade but ARP aging is usually specified in seconds, so 14400 might be more what you intended.
    – Zac67
    May 10, 2018 at 7:37
  • @Zac67 I had that thought too, but the docs specify minutes and if I attempt a value over 240 then it gets rejected by the CLI.
    – Elliot B.
    May 10, 2018 at 7:38


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