DHCP servers in lan

I have an office network with 5 wireless access point /routers giving access
to all areas of the office. They are connected via LAN cable to the central
switch. I have configured each one with DHCP with ranges which do not
overlap each other. I am told that this is a bad idea and that I should just
configure one of them as a DHCP server and disable the others for this.
If I do that , then only machines which are within range of the wireless
router config for DHCP can connect. Others, Since they can't reach the one
config for DHSP they cannot get IP addresses.
Is this normal?
How should I proceed please?
I prefer not to give fixed IP to all machines - about 50 .



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"-keevill-" <(E-Mail Removed)> wrote in message
news:4759f7df$0$26046$(E-Mail Removed).. .
>I have an office network with 5 wireless access point /routers giving
>access to all areas of the office. They are connected via LAN cable to the
>central switch. I have configured each one with DHCP with ranges which do
>not overlap each other. I am told that this is a bad idea and that I should
>just configure one of them as a DHCP server and disable the others for
>this.
> If I do that , then only machines which are within range of the wireless
> router config for DHCP can connect. Others, Since they can't reach the one
> config for DHSP they cannot get IP addresses.
> Is this normal?
> How should I proceed please?
> I prefer not to give fixed IP to all machines - about 50 .
>

Question: Why not setup a central DHCP server (separate from the access
points) for wired and wireless clients? I guess I am curious if you have
any wired clients? If so - how are they getting their addresses? Can you
use the same server you are using for DNS?

> Question: Why not setup a central DHCP server (separate from the access
> points) for wired and wireless clients? I guess I am curious if you have
> any wired clients? If so - how are they getting their addresses? Can you
> use the same server you are using for DNS?

There is only 1 hard wired client- with fixed IP.
DNS is provided via ISP and local wireless clients seem to discover dns
provided they can either connect to DHCP server direct or are given fixed IP
..



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> DNS is provided via ISP and local wireless clients seem to discover dns
> provided they can either connect to DHCP server direct or are given fixed
IP

Seem to discover? Uh, this isn't something to be vague about.

I'd much rather have centralized DHCP. One added benefit to this is being
able to better diagnose networking problems using DHCP leases. The machines
boot themselves as DHCP but get the same IP address every time. This way if
a device is acting up it should be easy to find via logs and such. That and
you can easily see any new devices as they'll show up as new leases, not
reservations.

There's another point to consider, if you've got fifty machines then you've
got the chance that all routers may, at some point, have to issue leases to
every one of them. Just how large are the subnets?

Feh, the headaches of managing multiple routers aren't worth it. Turn it
off on them and use a centralized one with leases instead.

"Bill Kearney" <wkearney-99@hot-mail-com> wrote in message
news:(E-Mail Removed) t...
>> DNS is provided via ISP and local wireless clients seem to discover dns
>> provided they can either connect to DHCP server direct or are given fixed
> IP
>
> Seem to discover? Uh, this isn't something to be vague about.
>
> I'd much rather have centralized DHCP. One added benefit to this is being
> able to better diagnose networking problems using DHCP leases. The
> machines
> boot themselves as DHCP but get the same IP address every time. This way
> if
> a device is acting up it should be easy to find via logs and such. That
> and
> you can easily see any new devices as they'll show up as new leases, not
> reservations.
>
> There's another point to consider, if you've got fifty machines then
> you've
> got the chance that all routers may, at some point, have to issue leases
> to
> every one of them. Just how large are the subnets?
>
> Feh, the headaches of managing multiple routers aren't worth it. Turn it
> off on them and use a centralized one with leases instead.

Thank you but that is what I am trying to do . If you re-read my earlier
post, I indicate that the client pc's cannot obtain an IP other than ones
which are near the only router rigged up for DHCP.
Or is there something I must do to enable discovery of the DHCP server for
client machines ?



--
Posted via a free Usenet account from http://www.teranews.com

"Bill Kearney" <wkearney-99@hot-mail-com> wrote in message
news:(E-Mail Removed) t...
>> DNS is provided via ISP and local wireless clients seem to discover dns
>> provided they can either connect to DHCP server direct or are given fixed
> IP
>
> Seem to discover? Uh, this isn't something to be vague about.
>
> I'd much rather have centralized DHCP. One added benefit to this is being
> able to better diagnose networking problems using DHCP leases. The
> machines
> boot themselves as DHCP but get the same IP address every time. This way
> if
> a device is acting up it should be easy to find via logs and such. That
> and
> you can easily see any new devices as they'll show up as new leases, not
> reservations.
>
> There's another point to consider, if you've got fifty machines then
> you've
> got the chance that all routers may, at some point, have to issue leases
> to
> every one of them. Just how large are the subnets?
>
> Feh, the headaches of managing multiple routers aren't worth it. Turn it
> off on them and use a centralized one with leases instead.


Thank you but that is what I am trying to do . If you re-read my earlier
post, I indicate that the client pc's cannot obtain an IP other than ones
which are near the only router rigged up for DHCP.
Or is there something I must do to enable discovery of the DHCP server for
client machines ?



--
Posted via a free Usenet account from http://www.teranews.com

"-keevill-" <(E-Mail Removed)> wrote in message
> Thank you but that is what I am trying to do . If you re-read my earlier
> post, I indicate that the client pc's cannot obtain an IP other than ones
> which are near the only router rigged up for DHCP.
> Or is there something I must do to enable discovery of the DHCP server for
> client machines ?

Are all the AP's actually AP's or are they wireless routers acting as AP's?
The latter is fine but you have to plug into a LAN port not it's WAN port.
(sorry if you know this but something doesn't sound right)
Also are all AP's using the same SSID and encryption info? The only thing
that should be different about each AP is the IP address and wireless
channel (make sure they are not all on the same channel.)

Your network should look like this

Internet Modem to WAN of Internet Router/AP1 with DHCP enabled, from it's
LAN port 1-4 (if applicable) to each of the 4 other AP's setup with static
addresses outside of the DHCP range of Router/AP1.
With this setup all wireless devices that associate with any of the AP's
will receive a DHCP lease from the internet router and all non lan traffic
with be routed to the internet via it's default gateway.

I would setup like this
router/AP - 192.168.1.254, DHCP 192.168.1.100-199
AP1-4 - 192.169.1.201-204.

Adair

"Adair Winter" <(E-Mail Removed)> wrote in message
news:Td37j.6860$(E-Mail Removed)...
> "-keevill-" <(E-Mail Removed)> wrote in message
>> Thank you but that is what I am trying to do . If you re-read my earlier
>> post, I indicate that the client pc's cannot obtain an IP other than ones
>> which are near the only router rigged up for DHCP.
>> Or is there something I must do to enable discovery of the DHCP server
>> for client machines ?
>
> Are all the AP's actually AP's or are they wireless routers acting as
> AP's? The latter is fine but you have to plug into a LAN port not it's WAN
> port. (sorry if you know this but something doesn't sound right)
> Also are all AP's using the same SSID and encryption info? The only thing
> that should be different about each AP is the IP address and wireless
> channel (make sure they are not all on the same channel.)
>
> Your network should look like this
>
> Internet Modem to WAN of Internet Router/AP1 with DHCP enabled, from it's
> LAN port 1-4 (if applicable) to each of the 4 other AP's setup with static
> addresses outside of the DHCP range of Router/AP1.
> With this setup all wireless devices that associate with any of the AP's
> will receive a DHCP lease from the internet router and all non lan traffic
> with be routed to the internet via it's default gateway.
>
> I would setup like this
> router/AP - 192.168.1.254, DHCP 192.168.1.100-199
> AP1-4 - 192.169.1.201-204.

Something may be wrong here... I Have all the routers set up with different
SSID. Something like AccessPoint1... APKichen..APAccounts etc... they are
all using NO encryption till I get it working correctly. Some of them are
using CH6 and some CH11. About half each.
Does the SSID hold a clue here ?




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"-keevill-" <(E-Mail Removed)> hath wroth:

>I have an office network with 5 wireless access point /routers giving access
>to all areas of the office. They are connected via LAN cable to the central
>switch. I have configured each one with DHCP with ranges which do not
>overlap each other.

Bad idea.

>I am told that this is a bad idea and that I should just
>configure one of them as a DHCP server and disable the others for this.

I think I was the one that suggested you do that. I'm too lazy to
lookup the previous thread and supply a reference.

>If I do that , then only machines which are within range of the wireless
>router config for DHCP can connect. Others, Since they can't reach the one
>config for DHSP they cannot get IP addresses.
>Is this normal?

Nope. That's not normal. It should work. I have several systems,
including my palatial office, setup that way. However, I don't recall
the details. Where you can go wrong is:
1. If you have all your access points or routers setup as routers.
That won't work as the DHCP broadcast has to go from the LAN->WAN
interface.
2. If your unspecified hardware has a problem passing broadcasts to
or from the LAN to the wireless interfaces. Note that DCHP is done
with broadcasts and do not require an IP address to function.
3. You have some device between the access point LAN ports that you
didn't mention (such as an overly smart managed switch, VLAN, VPN, or
router).

>How should I proceed please?
>I prefer not to give fixed IP to all machines - about 50 .

Easy. Download a DHCP/BOOTP query tool:
<http://www.weirdsolutions.com/weirdSolutions/files/products/desktopSoftware/desktopQueryTool/querytool_free.exe>
Fire it up on your LAN/WLAN and see if it can find a DHCP server. Type
anything you want into the "device identifier" field. No need to
assign an IP address. In fact, you can intentionally assign a totally
wrong IP address to the client and it should still work as it's all
running on the MAC layer. I just tried it with my static IP assigned
workstation and it works fine. Here's the results:
option PKT:Opcode=2
option PKT:HType=1
option PKT:HLen=2
option PKT:Hops=0
option DHCP message type=5
option PKT:Flags=32768
option PKT:Seconds=0
option PKT:XID=41
option PKT:SName=
option PKT:Boot file=
option PKT:CIAddr=0.0.0.0
option PKT:YIAddr=192.168.1.100
option PKT:SIAddr=192.168.1.1
option PKT:GIAddr=0.0.0.0
option PKT:Magic cookie=99.130.83.99
option Subnet mask=255.255.255.0
option Gateways=192.168.1.1
option Domain name servers=192.168.1.1
option Broadcast address=192.168.1.255
option Server identifier=192.168.1.1
option DHCP address lease time=7200
option DHCP renewal time=3600
option DHCP rebinding time=6300
option PKT:CHAddr=00-00

The test to run is very simple. Try the DHCP query first from locally
connected via CAT5 laptop. First try plugging it into the unspecified
device acting as a router and DHCP server. That should work and give
you a clue as to what to expect. Next, plug in to one of the routers
you have setup as an access point (with DHCP server disabled). That
should also work. Note that we have done NOTHING that involves
wireless at this time. Try it with your other access points. If the
access point does not have a built in ethernet switch, borrow a cheapo
ethernet switch, and install it between the backhaul cable and the
access point.

One you have determined that it works via the wired CAT5 network, try
it via wireless. There's a real possibility that it will not work
because of problems passing broadcasts between wired and wireless.
Look for settings such as "AP isolation" or "client isolation" that
will cause such problems. If you experience this problem, please
disclose the exact hardware, hardware version, firmware version of the
access point so I can raise hell with the manufactory.

--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Jeff Liebermann <(E-Mail Removed)> hath wroth:

>Easy. Download a DHCP/BOOTP query tool:
><http://www.weirdsolutions.com/weirdSolutions/files/products/desktopSoftware/desktopQueryTool/querytool_free.exe>

A bit more on using the above DHCP query tool:

1. Do NOT check the box for "use BOOTP protocol".

2. Windoze, in its infinite wisdom, caches DHCP requests. You can
sorta tell by how long it takes to return results. If it takes about
2-3 seconds, it's a new lookup. If it responds instantly, then it's
coming from the local cache.

3. I couldn't figure out how to clear the DHCP cache, so I found it
easier to just convince the lookup tool to do a new lookup. To do
that:
- Punch the "Reset" button to clear the display
- Change the "Device Identifier" to something unique.
If you watch the "your address" box, it will return a different IP
address (at least it does that with my static IP system).

--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558