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From: Rahul on 11 May 2010 01:57
Usually I assign essentially static I/Ps based on MAC addresses via a DHCP
server. i.e. the day a new server is added to the network a unique
association between its MAC and I/P is developed. (by manually adding its
eth0 MAC to the dhcpd.conf file)

But now, each server will be having twin etc cards. The new cards (eth2, 10
GigE) are on their seperate subnet with their seperate netmask etc. It
would be convinient to have some sort of logical association between the
IPs though. i.e. 10.0.0.1 <--> 192.168.0.1 etc. for the same machine.

Now I could run another dhcp server on this subnet too but that seems
redundant. Also, this means I'd have to manually note the addresses of all
my new cards too and then add them to the dhcpd server.

Is it possible for a client to query using eth0 the corresponding DHCP
server and then get an IP (say, 10.0.0.1) not only for eth0 but also for
eth1 (say, 192.168.0.1)? If this is a stupid idea perhaps, are there any
alternatives?

--
Rahul
From: J G Miller on 11 May 2010 09:00
On Tue, 11 May 2010 05:57:36 +0000, Rahul wrote:

> Usually I assign essentially static I/Ps based on MAC addresses via a
> DHCP server.

What is the advantage of assigning fixed IP addresses in this manner
using DHCP rather than just using a fixed IP in the network configuration
of the machine its-self?

Furthermore, if a fault develops on the network card and it has to be
replaced, then you would have to get the MAC address of the new card
and update the MAC address on the DHCP configuration.

Presumably there is something of which I am not aware that leads you
to assigning the fixed addresses via DHCP, so I look forward to your
answer.
From: unruh on 11 May 2010 10:37
On 2010-05-11, Rahul <nospam(a)nospam.invalid> wrote:
> Usually I assign essentially static I/Ps based on MAC addresses via a DHCP
> server. i.e. the day a new server is added to the network a unique
> association between its MAC and I/P is developed. (by manually adding its
> eth0 MAC to the dhcpd.conf file)
>
> But now, each server will be having twin etc cards. The new cards (eth2, 10
> GigE) are on their seperate subnet with their seperate netmask etc. It
> would be convinient to have some sort of logical association between the
> IPs though. i.e. 10.0.0.1 <--> 192.168.0.1 etc. for the same machine.
>
> Now I could run another dhcp server on this subnet too but that seems
> redundant. Also, this means I'd have to manually note the addresses of all
> my new cards too and then add them to the dhcpd server.
>
> Is it possible for a client to query using eth0 the corresponding DHCP
> server and then get an IP (say, 10.0.0.1) not only for eth0 but also for
> eth1 (say, 192.168.0.1)? If this is a stupid idea perhaps, are there any
> alternatives?

The main requirement is that the addresses be unique. Thus you could put
software onto each of the machines to assign the 10GB card the address
you want. You will have to make sure that it does it properly so that
each card gets a unique IP. Otherwise you will have a mess.
A machine does not have to "ask" for an IP. It can assign its own. But
if it does so, it has to make sure that that self assigned IP is unique.
(if a private net, (10.x.x.x, 192.168.x.x etc) unique to that subnet,
and if a public unique to the world)


>
From: Rahul on 11 May 2010 20:41
J G Miller <miller(a)yoyo.ORG> wrote in news:hsbkdr$eod$2(a)news.eternal-
september.org:

> What is the advantage of assigning fixed IP addresses in this manner
> using DHCP rather than just using a fixed IP in the network configuration
> of the machine its-self?

Not sure if there is a clear advantage but it's how we have always being
doign this. Maybe it reduces some work in having the PXE net install script
dynamically change the IP each time. The MAC becomes an invarient for a
particular machine.

> Furthermore, if a fault develops on the network card and it has to be
> replaced, then you would have to get the MAC address of the new card
> and update the MAC address on the DHCP configuration.

True.



--
Rahul
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