[Dnsmasq-discuss] DHCP Relay, assign address from other vlan, with no dhcp listening on it

SpiderX spiderx at spiderx.dp.ua
Thu Sep 15 16:38:37 BST 2011


On Thu, Sep 15, 2011 at 6:05 PM, Michael Rack
<michael.rack at rsm-freilassing.de> wrote:
>
> Why is schema 2 safe you one ip per interface? You need a ip-address for
> routing, so that should be that ip-address dnsmasq is listing on. Or is
> your router not the same device where your dnsmasq is running on?
>
> Have your interfaces a /30 Network assigned? Or are they all bind on a
> bridged interface on your Unix-Router with only one ip-address-range /24
> or something else?
>
> Liebe Grüße aus Freilassing,
>
> Michael Rack
> RSM Freilassing
> --
> RSM Freilassing                 Tel.: +49 8654 607110
> Nocksteinstr. 13                Fax.: +49 8654 670438
> D-83395 Freilassing            www.rsm-freilassing.de
>
>
> Am 15.09.2011 14:25, schrieb SpiderX:
> > On Wed, Sep 14, 2011 at 5:42 PM, richardvoigt at gmail.com
> > <richardvoigt at gmail.com>  wrote:
> >>> I don't agree. Dnsmasq is a great software, I use it for years in a
> >>> small environment.
> >>> In bigger networks usage of l2 switches is necessary, and as Michael,
> >>> I dont know too any l2 switch that supports any dhcp-related RFC,
> >>> except 3046.
> >>> There are not some many unix dhcp software that can be used with l2
> >>> switches, dnsmasq could be one of it. And, as I said earlier, it
> >>> should be.
> >>> Solution with taking preference circuit-id and remote-id over
> >>> sub-option 5 can be implemented as switch, documented with warning in
> >>> manual, not enabled by default in example config.
> >> dnsmasq works great in conjunction with L2 switches.  Usually you put
> >> the dnsmasq node on a VLAN trunk port, that way it sees requests from
> >> all circuits, along with the VLAN tag.  I'm not sure why you've chosen
> >> to relay to a non-trunk port instead.
> > Let's take a look on situation. There is a network with access type
> > vlan per user or vlan per switch (not fundamentally),
> > which builded on globally routed ip addresses (I mean "white ips", not
> > 10.0.0.0/8, etc.)
> >
> > Sheme 1
> > client — broadcast — l2 switch's port 1 — broadcast — server (dhcp
> > listening on interface with utilization of one ip in subnet)
> > client — broadcast — l2 switch's port 2 — broadcast — server (dhcp
> > listening on interface with utilization of one ip in subnet)
> > ..............
> > client — broadcast — l2 switch's port 24 — broadcast — server (dhcp
> > listening on interface with utilization of one ip in subnet)
> >
> > Sheme 2
> > client — broadcast — l2 switch's port 1 — unicast — server (dhcp
> > listening on interface with utilization of one ip in subnet)
> > client — broadcast — l2 switch's port 2 — unicast — server (dhcp
> > listening on interface with utilization of one ip in subnet)
> > .............
> > client — broadcast — l2 switch's port 24 — unicast — server (dhcp
> > listening on interface with utilization of one ip in subnet)
> > Dhcp is listening on one interface and utilizes one ip address. This
> > ip/interface is not directly accessible by clients.
> >
> > Which of these schemes is more safer and more reliable?
> > Which of these schemes is easier to maintain?
> > Which scheme is more economically viable? (I don't lose one ip per
> > interface with dhcp server listening on it. One ip = one client.)
> > Dnsmasq can be used in scheme 1, but not in scheme 2.
> >
> > _______________________________________________
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> > Dnsmasq-discuss at lists.thekelleys.org.uk
> > http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss
>
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> Or is your router not the same device where your dnsmasq is running on?
Exactly.

> Have your interfaces a /30 Network assigned? Or are they all bind on a
> bridged interface on your Unix-Router with only one ip-address-range /24
> or something else?
Actually It doesn't matter.
I use supervlan aka ip unnumbered in one network, in another (vlan per
switch) I use just a subnets /24, /25, /26 on interfaces.



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