Wireless router as Access Point - DHCP and all that

I've decided to pension off my elderly 3Com ADSL Wireless Modem/Router
because it crashes and needs re-booting too often for comfort. All my
regular computers are hard-wired anyway, so I don't need wireless on a
day to day basis, and have reverted to using a wires-only router.

However, I occasionally have house guests who bring laptops with them
and appreciate a wireless connection. So I'm proposing to fire up the
3Com jobbie on those occasions, and connect it by ethernet to the
principal router so that it just acts as a wireless access point. I
shall give it a fixed IP address - in the same subnet as the rest of my
network, but outside the range of addresses dished out by the DHCP
server in my principal router.

The question is, what should I do about DHCP on the 3Com? If I switch it
off, will wireless devices which connect to it be able to get an IP
address from my principal router? If not, should I switch it on, and let
it dish out addresses in the same subnet but different range from the
principal router? If I do that, will having two active DHCP servers
cause confusion?

Advice please.
--
Cheers,
Roger
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"Roger Mills" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> I've decided to pension off my elderly 3Com ADSL Wireless Modem/Router
> because it crashes and needs re-booting too often for comfort. All my
> regular computers are hard-wired anyway, so I don't need wireless on a day
> to day basis, and have reverted to using a wires-only router.
>
> However, I occasionally have house guests who bring laptops with them and
> appreciate a wireless connection. So I'm proposing to fire up the 3Com
> jobbie on those occasions, and connect it by ethernet to the principal
> router so that it just acts as a wireless access point. I shall give it a
> fixed IP address - in the same subnet as the rest of my network, but
> outside the range of addresses dished out by the DHCP server in my
> principal router.
>
> The question is, what should I do about DHCP on the 3Com? If I switch it
> off, will wireless devices which connect to it be able to get an IP
> address from my principal router? If not, should I switch it on, and let
> it dish out addresses in the same subnet but different range from the
> principal router? If I do that, will having two active DHCP servers cause
> confusion?

I've not done this myself but I'm told you need to switch off the DHCP on
the router that's just acting as the Wireless Access Point.

Also I believe the bit you wrote about giving it a fixed IP isn't relevant
to it's functioning as an access point as such, but will allow access to
configure it when necessary.

--

Brian Gregory. (In the UK)
(E-Mail Removed)
To email me remove the letter vee.

Roger Mills <(E-Mail Removed)> wrote:
> The question is, what should I do about DHCP on the 3Com? If I switch it
> off, will wireless devices which connect to it be able to get an IP
> address from my principal router? If not, should I switch it on, and let
> it dish out addresses in the same subnet but different range from the
> principal router? If I do that, will having two active DHCP servers
> cause confusion?

I set up a network with 4 routers, one 'master' and three 'slaves', cabled
up by ethernet. The slaves had DHCP turned off and were set up as you say.
The master was running the upstream connection and the DHCP server. For
simplicity each router was set up with a different SSID, as they were all
from different manufacturers (is it easy to get heterogenous APs on the same
SSID, with roaming between?). The main interest was internet access: I
wasn't expecting any communication between clients.

It worked fine. An advantage is that you can 'see' if the master router is
down - Windows will say that it can't make a connection (ie can't get an IP
address). If you have each running DHCP themselves, you can get
connectivity to the local router but it isn't immediately obvious that the
gateway is down. This isn't so helpful if you might want to be able to
communicate between clients when the upstream router is down.

Theo

Theo Markettos wrote:
> Roger Mills <(E-Mail Removed)> wrote:
>> The question is, what should I do about DHCP on the 3Com? If I switch it
>> off, will wireless devices which connect to it be able to get an IP
>> address from my principal router? If not, should I switch it on, and let
>> it dish out addresses in the same subnet but different range from the
>> principal router? If I do that, will having two active DHCP servers
>> cause confusion?
>
> I set up a network with 4 routers, one 'master' and three 'slaves', cabled
> up by ethernet. The slaves had DHCP turned off and were set up as you say.
> The master was running the upstream connection and the DHCP server. For
> simplicity each router was set up with a different SSID, as they were all
> from different manufacturers (is it easy to get heterogenous APs on the same
> SSID, with roaming between?). The main interest was internet access: I
> wasn't expecting any communication between clients.
>
> It worked fine. An advantage is that you can 'see' if the master router is
> down - Windows will say that it can't make a connection (ie can't get an IP
> address). If you have each running DHCP themselves, you can get
> connectivity to the local router but it isn't immediately obvious that the
> gateway is down. This isn't so helpful if you might want to be able to
> communicate between clients when the upstream router is down.
>

worse than that, the slave router will advertise itself as a default
route. Which it isn't.

It's merely acting as a WiFi BRIDGE.

If it does that successfully, inter machine traffic should not be affected.



> Theo

On Thu, 03 Mar 2011 21:26:28 +0000, Roger Mills wrote:

> I've decided to pension off my elderly 3Com ADSL Wireless Modem/Router
> because it crashes and needs re-booting too often for comfort. All my
> regular computers are hard-wired anyway, so I don't need wireless on a
> day to day basis, and have reverted to using a wires-only router.
>
> However, I occasionally have house guests who bring laptops with them
> and appreciate a wireless connection. So I'm proposing to fire up the
> 3Com jobbie on those occasions, and connect it by ethernet to the
> principal router so that it just acts as a wireless access point. I
> shall give it a fixed IP address - in the same subnet as the rest of my
> network, but outside the range of addresses dished out by the DHCP
> server in my principal router.
>
> The question is, what should I do about DHCP on the 3Com? If I switch it
> off, will wireless devices which connect to it be able to get an IP
> address from my principal router? If not, should I switch it on, and let
> it dish out addresses in the same subnet but different range from the
> principal router? If I do that, will having two active DHCP servers
> cause confusion?
>
> Advice please.

Have a similar situation - I have 2 subnets though and on each only one
DCHP server running but all my routers have fixed i/p address so I can look
at their setups (and connections) can be useful at times to diagnose
problems
--
(º•.¸(¨*•.¸ ¸.•*¨)¸.•º)
<.•°•. Nik .•°•.>
(¸.•º(¸.•¨* *¨•.¸)º•.¸)

"Roger Mills" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> I've decided to pension off my elderly 3Com ADSL Wireless Modem/Router
> because it crashes and needs re-booting too often for comfort. All my
> regular computers are hard-wired anyway, so I don't need wireless on a day
> to day basis, and have reverted to using a wires-only router.
>
> However, I occasionally have house guests who bring laptops with them and
> appreciate a wireless connection. So I'm proposing to fire up the 3Com
> jobbie on those occasions, and connect it by ethernet to the principal
> router so that it just acts as a wireless access point. I shall give it a
> fixed IP address - in the same subnet as the rest of my network, but
> outside the range of addresses dished out by the DHCP server in my
> principal router.
>
> The question is, what should I do about DHCP on the 3Com? If I switch it
> off, will wireless devices which connect to it be able to get an IP
> address from my principal router? If not, should I switch it on, and let
> it dish out addresses in the same subnet but different range from the
> principal router? If I do that, will having two active DHCP servers cause
> confusion?
>
Switch off DHCP in the 3com router. Make sure that the 3com router is not
using an IP address that conflicts with anything else on your network, but
is in the same subnet.

I do this with two routers from Speedtouch and Netgear. In my case both
routers have WiFi. I use the same SSID but different channels.


--
Michael Chare

On 04/03/2011 13:10, Michael Chare wrote:
> "Roger Mills" <(E-Mail Removed)> wrote in message
> news:(E-Mail Removed)...
>> I've decided to pension off my elderly 3Com ADSL Wireless Modem/Router
>> because it crashes and needs re-booting too often for comfort. All my
>> regular computers are hard-wired anyway, so I don't need wireless on a
>> day to day basis, and have reverted to using a wires-only router.
>>
>> However, I occasionally have house guests who bring laptops with them
>> and appreciate a wireless connection. So I'm proposing to fire up the
>> 3Com jobbie on those occasions, and connect it by ethernet to the
>> principal router so that it just acts as a wireless access point. I
>> shall give it a fixed IP address - in the same subnet as the rest of
>> my network, but outside the range of addresses dished out by the DHCP
>> server in my principal router.
>>
>> The question is, what should I do about DHCP on the 3Com? If I switch
>> it off, will wireless devices which connect to it be able to get an IP
>> address from my principal router? If not, should I switch it on, and
>> let it dish out addresses in the same subnet but different range from
>> the principal router? If I do that, will having two active DHCP
>> servers cause confusion?
>>
> Switch off DHCP in the 3com router. Make sure that the 3com router is
> not using an IP address that conflicts with anything else on your
> network, but is in the same subnet.
>
> I do this with two routers from Speedtouch and Netgear. In my case both
> routers have WiFi. I use the same SSID but different channels.
>
>

Many thanks for all the replies. As implied in my question, I was hoping
that it would work if I switched off DHCP on the 3Com Router.

I've now done it, and it *does*!
--
Cheers,
Roger
____________
Please reply to Newsgroup. Whilst email address is valid, it is seldom
checked.

"Roger Mills" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> On 04/03/2011 13:10, Michael Chare wrote:
>
> Many thanks for all the replies. As implied in my question, I was hoping
> that it would work if I switched off DHCP on the 3Com Router.
>

Like I said you should make sure that you don't have two devices (routers)
trying to use the same IP address.
Routers often come with addresses like 192.168.0.1

--
Michael Chare

Meanwhile, at the uk.telecom.broadband Job Justification Hearings, Theo
Markettos chose the tried and tested strategy of:

> I set up a network with 4 routers, one 'master' and three 'slaves', cabled
> up by ethernet. The slaves had DHCP turned off and were set up as you
> say. The master was running the upstream connection and the DHCP server.
> For simplicity each router was set up with a different SSID, as they were
> all from different manufacturers (is it easy to get heterogenous APs on
> the same SSID, with roaming between?).

Yes, shouldn't be a problem, but it's the client that decides when to roam
from one AP to the next, not the APs.

--
<http://ale.cx/> (AIM:troffasky) ((E-Mail Removed))
21:12:37 up 1 day, 1:36, 9 users, load average: 0.09, 0.19, 0.20
"I am utterly appalled at how I have been treated like a criminal"
-- Andrew Crossley, ACS:Law, 13 August 2010

On 04/03/2011 16:54, Michael Chare wrote:
> "Roger Mills" <(E-Mail Removed)> wrote in message
> news:(E-Mail Removed)...
>> On 04/03/2011 13:10, Michael Chare wrote:
>>
>> Many thanks for all the replies. As implied in my question, I was
>> hoping that it would work if I switched off DHCP on the 3Com Router.
>>
>
> Like I said you should make sure that you don't have two devices
> (routers) trying to use the same IP address.
> Routers often come with addresses like 192.168.0.1
>

Yes,I've done that too.

The new wired (Netgear) router defaults to 192.168.0.1 but the rest of
my network is in the 192.168.1.x (rather than 0.x) subnet, so I've
changed it to 192.168.1.110 and set the old 3Com jobbie to 192.168.1.100

I also have a VoIP ATA with a fixed IP address of 192.168.1.50 - and
I've set the DHCP server on the Netgear to dish out addresses between
192.168.1.80 and 90 - so there won't be any conflicts.
--
Cheers,
Roger
____________
Please reply to Newsgroup. Whilst email address is valid, it is seldom
checked.