[ale] dhcpd to multiple vlans from one server
Jim Kinney
jim.kinney at gmail.com
Thu Jan 22 21:54:28 EST 2015
On Fri, 2015-01-23 at 02:41 +0000, Robert L. Harris wrote:
> I have multiple projects/products, etc at work we are breaking into
> separate broadcast domains ( currently 11, likely to be closer to 20
> ). I don't want a different dhcp server per subnet/vlan. I can put a
> trunk port to the dhcp server so if I can have dhcpd answering on each
> vlan so I have centrally managed dhcp, that's ideal. So maybe I'm
> stuck doing the eth0.21, etc with an IP on each subnet and one dhcp
> server.
I think you can do it with a single, very high port count machine.
virtual nics won't do it. So a big box with x5 4 port nics with a line
to each head switch or a vlan'ed port will work. Each subnet get's it's
own stanza in the config file.
>
>
>
>
>
> On Thu Jan 22 2015 at 7:30:43 PM Jim Kinney <jkinney at jimkinney.us>
> wrote:
> +1. All it takes is a physical connection to the subnet.
>
> Not sure why separate vlans get assigned to separate subnets.
> It doesn't provide a benefit. Vlans are for having overlapping
> IP space in the same physical LAN. Which is only useful when a
> LAN fills up a 10. Class A. Maybe its easier at the
> switch/router management level with more than 100 subnets.
> Mostly, I see it used as a job guarantee for a network admin.
>
>
> On January 22, 2015 9:15:39 PM EST, Michael Trausch
> <mike at trausch.us> wrote:
> ISC dhcpd will hand an address out based on the
> interface it came in on. If if eth0 has 203.0.113.1/25
> and eth1 has 203.0.113.129/25, and the DHCP server is
> authoritative for those two subnetworks, then when it
> receives a request on eth0 for an address it will
> issue an address in 203.0.113.0/25; when it receives a
> request on eth1 it will issue an address in
> 203.0.113.128/25.
>
> Sent from my iPad
>
> On Jan 22, 2015, at 7:37 PM, "Robert L. Harris"
> <robert.l.harris at gmail.com> wrote:
>
>
> > Ok, so if I have 2 subnets:
> >
> > 172.20.1/24 on vlan 21
> > 172.20.2/24 on vlan 22
> >
> >
> > If a host plugs into a port assigned to vlan 22, how
> > do I make sure dhcpd gives out the right address?
> > That's the part of the designation I'm missing.
> >
> >
> > Robert
> >
> >
> >
> >
> > On Thu Ja n 22 2015 at 5:17:25 PM James Sumners
> > <james.sumners at gmail.com> wrote:
> > You just have to define the subnets in the
> > config and put each subnet's pool within its
> > respective block. No need for aliased IPs.
> >
> > On Thursday, January 22, 2015, Robert L.
> > Harris <robert.l.harris at gmail.com> wrote:
> >
> > Anyone have a dhcpd serving multiple
> > subnets to multiple vlans from a
> > single server on a trunk they can
> > share configs? I don't want to
> > spawn a bunch of servers and if I
> > can do it with a single interface
> > that would be ideal. If I have to
> > go with eth0.0, eth0.1, etc that's a
> > good second choice.
> >
> >
> > Robert
> >
> >
> >
> >
> > --
> > James Sumners
> > http://james.sumners.info/ (technical
> > profile)
> > http://jrfom.com/ (personal site)
> > http://haplo.bandcamp.com/ (band page)
> >
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>
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> --
> Jim Kinney
> Linux Systems Analyst
> Physicist/Brewer
> http://jimkinney.us
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--
James P. Kinney III
Every time you stop a school, you will have to build a jail. What you
gain at one end you lose at the other. It's like feeding a dog on his
own tail. It won't fatten the dog.
- Speech 11/23/1900 Mark Twain
http://heretothereideas.blogspot.com/
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