Netgear WGT624 won't forward DHCP?

Hi,
Trying to setup a Netgear WGT624 v2 (with firmware 4.2.6) as an access
point (not a router), I got frustrated that the clients would associate
to the WGT624 but not get an IP. I hadn't yet got around to sniffing
the network or anything, but I noticed a user's comments on Pricegrabber
that states that the WGT624 (like other Netgear devices, supposedly)
won't forward DHCP requests from the wirless side to the wired side.
Hence, my wireless clients' DHCP requests go unanswered by my existing
DHCP server.
Has anyone else verified that this is indeed intentional on the part of
Netgear, and do all their models behave this way? This seems ludicrous
to me. I have an existing router that I don't want to replace; if I
can't make the WGT624 behave as just an AP, it's going back.

Comments/suggestions?

TIA,
Jonathan

On Sun, 13 Mar 2005 11:54:44 -0500, Jonathan <(E-Mail Removed)>
wrote:

>Hi,
>Trying to setup a Netgear WGT624 v2 (with firmware 4.2.6) as an access
>point (not a router), I got frustrated that the clients would associate
>to the WGT624 but not get an IP. I hadn't yet got around to sniffing
>the network or anything, but I noticed a user's comments on Pricegrabber
>that states that the WGT624 (like other Netgear devices, supposedly)
>won't forward DHCP requests from the wirless side to the wired side.
>Hence, my wireless clients' DHCP requests go unanswered by my existing
>DHCP server.
>Has anyone else verified that this is indeed intentional on the part of
>Netgear, and do all their models behave this way? This seems ludicrous
>to me. I have an existing router that I don't want to replace; if I
>can't make the WGT624 behave as just an AP, it's going back.
>
>Comments/suggestions?

Are you using the DHCP server in the WGT624 or do you have a server
running a DHCP server on the wired LAN? Hopefully, you don't have
both running in the same IP address block.

DHCP requests are broadcasts and some router have setting to control
how broadcasts are handled. However, that's always between the LAN
and WAN side, not between two parts of the same LAN (wired and
wireless). By my astute guess(tm), broadcasts should always propogate
between the LAN and wireless.

One exception is if the WGT624 has some kind of "client isolation"
feature enabled. That is designed to prevent each client from
communicating with other clients as in a hot spot. If you have a
Linux or Windoze server running a DHCP server on the LAN side, this
"client isolation" feature will block everything including broadcasts
to the other LAN/wireless clients. No clue if the WGT624 has this
feature, but it's present and functional on the Linksys WRT54G.

You might wanna do some DHCP testing with a free tool:
http://www.weird-solutions.com/download/demo.html
Grab the DHCP Query Tool at the bottom of the page. That will let you
test how DHCP requests and responses are doing without sniffing.


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

Jeff Liebermann wrote:
> On Sun, 13 Mar 2005 11:54:44 -0500, Jonathan <(E-Mail Removed)>
> wrote:
>
>
>>Hi,
>>Trying to setup a Netgear WGT624 v2 (with firmware 4.2.6) as an access
>>point (not a router), I got frustrated that the clients would associate
>>to the WGT624 but not get an IP. I hadn't yet got around to sniffing
>>the network or anything, but I noticed a user's comments on Pricegrabber
>>that states that the WGT624 (like other Netgear devices, supposedly)
>>won't forward DHCP requests from the wirless side to the wired side.
>>Hence, my wireless clients' DHCP requests go unanswered by my existing
>>DHCP server.
>>Has anyone else verified that this is indeed intentional on the part of
>>Netgear, and do all their models behave this way? This seems ludicrous
>>to me. I have an existing router that I don't want to replace; if I
>>can't make the WGT624 behave as just an AP, it's going back.
>>
>>Comments/suggestions?
>
>
> Are you using the DHCP server in the WGT624 or do you have a server
> running a DHCP server on the wired LAN? Hopefully, you don't have
> both running in the same IP address block.
>
> DHCP requests are broadcasts and some router have setting to control
> how broadcasts are handled. However, that's always between the LAN
> and WAN side, not between two parts of the same LAN (wired and
> wireless). By my astute guess(tm), broadcasts should always propogate
> between the LAN and wireless.
>
> One exception is if the WGT624 has some kind of "client isolation"
> feature enabled. That is designed to prevent each client from
> communicating with other clients as in a hot spot. If you have a
> Linux or Windoze server running a DHCP server on the LAN side, this
> "client isolation" feature will block everything including broadcasts
> to the other LAN/wireless clients. No clue if the WGT624 has this
> feature, but it's present and functional on the Linksys WRT54G.
>
> You might wanna do some DHCP testing with a free tool:
> http://www.weird-solutions.com/download/demo.html
> Grab the DHCP Query Tool at the bottom of the page. That will let you
> test how DHCP requests and responses are doing without sniffing.
>
>

There is an existing firewall/router, with DHCP server, on that segment.
So you disable the DHCP server in the wireless router, and connect
the upstream router to one of the wireless router's LAN ports. For most
models, this implementation effectively makes them access points, not
routers.
So when this is done with the WFT624, the wireless clients associate to
the network just fine, only they never get an IP from the upstream
router. It has been suggested that this is a Netgear "feature."
If the WGT624 has the "client isolation" capability you mention, there
is no reference to it in the configuration GUI.

I had forgotten about the DHCP query tool, I'll give that a shot.

Thanks!

On Tue, 15 Mar 2005 11:39:47 -0500, Jonathan <(E-Mail Removed)>
wrote:

>There is an existing firewall/router, with DHCP server, on that segment.

Well, if things appear to be incureable in the Netgear WFT624, then
enable the DHCP server in the WFT624. Make sure that it's range of IP
addresses delivered do NOT overlap those delivered by your LAN
firewall/router DHCP server. The catch is that some wireless routers
do not allow you to specify a default gateway other than that of the
routers LAN IP address. I don't recall exactly which models do this,
but it's epidemic. If the client points to the WFT624 as the default
gateway, it won't work. You could force the default gateway in the
client computers to the firewall/router, but that will rapidly become
a maintenance and setup headache.

> So you disable the DHCP server in the wireless router, and connect
>the upstream router to one of the wireless router's LAN ports. For most
>models, this implementation effectively makes them access points, not
>routers.

Correct. It's actually cheaper to buy a wireless router and use it as
an access point, than to buy an access point. You also usually get a
4 port switch along with the router that's missing in the access point
version.

>So when this is done with the WFT624, the wireless clients associate to
>the network just fine, only they never get an IP from the upstream
>router. It has been suggested that this is a Netgear "feature."

I don't think it's an intentional feature. Something is blocking
broadcasts between the wired LAN ports and the wireless. I guess it's
time to play sniff some traffic.

Incidentally, I worked on a Dell 8200 with XP SP2 on the bench that
absolutely would not deliver an DHCP IP address from an early BEFW11S4
v2 wireless router when encryption was enabled. Turn it off
encryption and it works. I've seen this several times with other
wireless routers and have never bothered to investigate the exact
connection between WEP encryption and DHCP broadcasts. Anyway, try it
with encryption disabled and see if DHCP magically returns.

>If the WGT624 has the "client isolation" capability you mention, there
>is no reference to it in the configuration GUI.
>
>I had forgotten about the DHCP query tool, I'll give that a shot.


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