multi interfaces(vlans) configuration

Ahiya Zadok ahiya at
Tue Oct 13 10:59:19 UTC 2020

Eventually, I understood that the DHCP relay limitation isn't real
I was misled by the vendor's support engineer.

Thank you all for responding

-----Original Message-----
From: dhcp-users <dhcp-users-bounces at> On Behalf Of Simon
Sent: Friday, October 9, 2020 5:17 PM
To: Users of ISC DHCP <dhcp-users at>
Subject: Re: multi interfaces(vlans) configuration

> On 9 Oct 2020, at 07:02, sthaug at wrote:
>> ISC dhcpd needs to access the raw ethernet interface, so doesn't play
>> well with vlan sub-interfaces.
> "Doesn't play well with vlan sub-interfaces" may be the case for Linux.
> We're running ISC dcpd with multiple VLANs on FreeBSD, and it seems to
> work just fine.

I'm pretty certain I've done it with linux in the past. Does "raw packet"
literally mean "packet from the NIC buffer", or does it mean "packet from
the OS buffer after the OS has done the VLAN stuff" ?
Without any knowledge of how it's actually done, it would seem logical to
me for the VLAN (and link aggregation/bonding) code to handle that aspect
before squirting the packet into the packet buffer ready to go into the
rest of the network stack. So tagged packet in -> tag stripped by VLAN
code -> packet put into buffer as though it had been received that way
(untagged) on that interface.

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