Ethernet Switches & Routers

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New Contributor
Posts: 2
Registered: ‎09-09-2011

Dynamic ARP Inspection + HP Printer problems

I'm testing Dynamic Arp Inspection and DHCP snooping on one of our switches in preparation for possible wider deployment. I'm noticing some issues with printers I have connected thus far on my un-trusted ports. It seems like a lot of HP printers are not very good about checking into DHCP server on-time when their lease is running up. In other words, this appears to be a problem with their DHCP client, I didn't see anything with the HPs to fix this so far.

I was looking through the manual and was hoping there was some kind of 'grace-time' setting or perhaps something to try to force these guys to re-submit a DHCP request on the switch when used in conjunction with DAI/DHCP snooping. Have any of you experienced this this problem from other users and do you have any recommendations? Obviously I could manually add each printer to the ARP list on the accompanying switch, but I'd rather not have to add this level of management if I don't have to.

You guys seen this issue or have any suggestions?
Thanks!
-Mike

Switch = FGS-24G

Firmware = 07.2.02eT7e1

Contributor
Posts: 61
Registered: ‎12-08-2009

Re: Dynamic ARP Inspection + HP Printer problems

You can use dhcp-server commands in order to have fine tuning. default-lease-time and max-lease-time commands may be helpful.

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New Contributor
Posts: 2
Registered: ‎09-09-2011

Re: Dynamic ARP Inspection + HP Printer problems

Thanks for the advice. I'm running DHCP off another server though rather than the switches. I suppose I could adjust the lease times there but that has the side-effect of potentially causing issues across the rest of our clients.

I'm getting the feeling I'm going to have to manually add ARP entries for each printer. Does anyone else use DAI in their environment and have this same issue with printers being bad DHCP clients?

Thanks again for any advice!

-Mike

Frequent Contributor
Posts: 117
Registered: ‎07-26-2010

Re: Dynamic ARP Inspection + HP Printer problems

Hi Mike,

I am running DAI & DHCP Snooping in about 70 Switches / about 6000 ports for several VLANs.

We have not seen any problems like you.

I do not now any tuning abilities on the switches so far.

DHCP snooping is only listening on the client & server packets; no more intelligence.

But I have seen other issues that the chassis switch looses DHCP snooping entries on mgmt card switch-over.

Cheers

Karlheinz

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