High ram-usage with multiple /16 ipv4 networks

Peter Rathlev peter at rathlev.dk
Tue Apr 21 12:31:10 UTC 2015

On Tue, 2015-04-21 at 13:07 +0200, Ruben Wisniewski wrote:
> Am Mon, 20 Apr 2015 18:48:12 +0200
> schrieb Peter Rathlev <peter at rathlev.dk>:
> > Wouldn't the "deny all clients" statements make those ranges a no-op?
> > So each subnet has just 2558 available leases? But maybe this is just
> > testing?
> We need this deny all clients statement because of our routing-protocol.
> The protocol is rerouting all dhcp traffic to the dhcpd-server which
> have the best connection. So all other dhcp-servers does not get the
> DHCPINFORM/DHCPREQUEST. So we need to activly deny the
> other ranges, because no other dhcp-server will respond to the querys.

Ah, okay. I had thought that "authoritative" would NAK those, but I can
see that it doesn't.

> I think the part which is constantly increasing is the nameserver's
> cache.

That's not really related to the dhcpd though, is it?

>  > I'd say it looks normal. Running a DHCP server for 1.5 million leases
> > is no small feat. Running a server at all with just 512 MBytes of RAM
> > sounds like asking for trouble anyway. (RAM inflation, I know, but RAM
> > is cheap these days.)
> Actually we just use the 2558 leases, not the 1.5 million ones. Since
> the config says, that no client will ever use the other pool.

No, you have configured 1.5 million leases. That you do not use them
does not mean that they do not exist.

So still: It sounds normal.


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