I am not a network engineer, I have very limited knowledge.


We currently have a HP1920-48g switch + others around our building. Originally these were "daisy chainned", the new I.T Director changed this into what he describes as a "spider" like configuration (totally not a tech term im thinking).


We have just installed a new telephone IP system, which works with a little computer software called "navigate" recently people coming in later to the building trying to access this would result in a long wait untill there settings loaded etc.

Now we have traced this to a issue with the switch reaching 256 limit in the ARP table.


Can we increase this limit, ither purchase a new switch (rather not but understand if we must).

Or can we set up something to increase the limit somehow? Unfortunatly I have very little network knowledge. We played around with turning of the Gratuitous ARP but not really sure that we should do this.

  • Switches don't use ARP tables, they have MAC address tables. ARP is used to resolve a layer-3 address to a layer-2 address, but switches don't know or care about layer-3 addresses. Switches do care about which ports have which MAC addresses, so they maintain MAC address tables. This is a very different concept than ARP.
    – Ron Maupin
    Jan 25, 2017 at 15:51
  • The more common term for "spider" configuration is "star" - it reduces the number of transits data has to make going from what would have been one end of the "daisy-chain" to the other by providing a central node that's only one hop from each access switch, so each access switch is only two hops from every other access switch.
    – Ecnerwal
    Jan 26, 2017 at 17:30
  • Did either answer help you? If so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer.
    – Ron Maupin
    Jul 24, 2017 at 22:18

2 Answers 2


Are you sure this has anything to do with ARP? The 1920 is a layer2 switch and doesn't need to do any ARP.

I'd suspect it has more to do with the subnet size especially the DHCP scope. Once IP address allocation is exhausted - which for the most common /24 subnet size is 256 (or rather 254), you need to enlarge the network. If you've just got this single subnet it's not too hard to do.


It sadly does have that limit of 256 entries. Perhaps there will be a "Comware 7" upgrade to this switch which will increase that limit, perhaps it won´t. But you can try to disable gratuitous ARP packets learning function (Network -> ARP Management -> Gratuitous ARP)and delete dynamic ARP records.

Hope this will work.

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