Frame Tagging

Simon Hobson dhcp1 at
Sat Aug 3 08:48:47 UTC 2013

Christian Kratzer wrote:
>I never really run my dhcp servers with multiple legs into different networks.
>I usually just setup dhcp relays to the dhcp servers from the routers connecting to the different network segments (vlans).
>Matter of fact its quite normal for me to have the dhcp servers in separate vlans where there is not a single client.
>Makes for a much cleaner and simpler setup than the mess of having to put the server into each and every segment / vlan.

Depends on your network setup. The only time I've done DHCP on multiple VLANs, the server was the router - it was a gateway for a multi-tenant setup.
But I agree, if your topology works out like that, there's a lot to be said for just relaying packets to the server rather than linking it to each network - and that applies regardless of whether the network uses VLANs or not.

Alex Bligh wrote:
>> I think the problem is the way dhcpd directely accesses the raw packets rather than using the OS IP stack. It does this due to the need to handle packets without an IP address to talk to clients that haven't yet configured their stack.
>This makes sense for dhcp client but less for dhcdpd

dhcdpd ?
Assuming you meant to write dhcpd, I disagree. I don't know the details, but AIUI there are packet operations the server needs to be able to do which cannot be done through the IP stack.
There is a compile time option to turn off this direct access, but then the serve cannot handle local clients (ie those not handled via a relay agent).

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