MarktheNerd
asked on
ARP Broadcast Storms with HP 1910 switches
Hello,
We’ve started deploying HP 1910 8 port switches to isolated areas of our network, because they are reasonably priced. Our core devices are HP 28xx series switches and Cisco 29xx series switches.
We’ve noticed that the HP 1910 units aggressively broadcast ARP requests for everything in their ARP tables. We have about 30 of the 1910’s now, and they’re responsible for 90% of our internal network traffic—2,000-4,000 packets per second of nothing but ARP requests.
It does calm down every now and then—you might get 30 seconds while nothing is transmitting, then it starts up again. Watching an individual switch’s traffic, they seem to chatter every 2-3 minutes, which roughly matches the ARP ageing default. The problem is, for an ARP table with 100 entries, it might send 20k ARP requests!
Does anyone have any ideas on how to make these calm down, or at least make them act like our Cisco and 28xx series switches, that don’t have this kind of flooding issue?
We’ve started deploying HP 1910 8 port switches to isolated areas of our network, because they are reasonably priced. Our core devices are HP 28xx series switches and Cisco 29xx series switches.
We’ve noticed that the HP 1910 units aggressively broadcast ARP requests for everything in their ARP tables. We have about 30 of the 1910’s now, and they’re responsible for 90% of our internal network traffic—2,000-4,000 packets per second of nothing but ARP requests.
It does calm down every now and then—you might get 30 seconds while nothing is transmitting, then it starts up again. Watching an individual switch’s traffic, they seem to chatter every 2-3 minutes, which roughly matches the ARP ageing default. The problem is, for an ARP table with 100 entries, it might send 20k ARP requests!
Does anyone have any ideas on how to make these calm down, or at least make them act like our Cisco and 28xx series switches, that don’t have this kind of flooding issue?
ASKER
So even though only one specific switch model has the issue, it's a network design problem? Why wouldn't the other switches be displaying the same behavior, if it was a design issue?
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ASKER
I think the STP thing is probably on the right path. I haven't been able to figure out how to do portfast (Portfast is Cisco, this is HP, so I'm trying to find the equivalent), but if I disable STP on a given switch, the broadcasts stop immediately. I'll see if I can figure out the specific settings to keep it from happening now.
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ASKER
It's still being a bit odd, but at least we know the root cause now. Disabling STP is the Band-Aid we need until we can figure out the specific STP configuration we need. Thanks, Predrag!!!
a) you need to reduce number of hosts per VLAN
b) maybe there's a network loop
c) you need to set ports for host to portfast to reduce broadcast (this is optional and short term solution)