Problem when using 2 APs WAP54GP

Hi,

I am setting up a network with 2 APs WAP54GP connected with a hub.

AP1 <-> HUB <-> AP2
|
PC

The AP1:192.168.1.241 and AP2: 192.168.1.242.
I am using different SSID and different channels.
Then I have one PC connected to the hub and one laptop which I connect
to the wireless AP1.

First I connnect the laptop to AP1:

Laptop <-> AP1 <-> HUB <-> AP2
|
PC

The connectivity is fine and I can ping the AP1, AP2 and the PC.
Then, I disconnect from AP1, I move the laptop to the AP2, and I
connect to AP2.

AP1 <-> HUB <-> AP2 <-> Laptop
|
PC

Here is when I start to have problems.
The connection to AP2 is fine and I can ping it. But, I cannot ping the
AP1 or the wire PC.
This problem happens during 15 minutes, and after this time period the
connectivity is back.
It seems that it is a problem with an agingtime that blocks the AP from
forwarding traffic.

After putting a sniffer in the laptop and the PC, I could tell that the
traffic is forwarded
by the AP from the wireless to the wire but the traffic from the wire
to the PC is not forwarded
to the wireless. This means that any arp sent by the laptop is seen in
the wire, but any arp reply
is not sent to the Wireless.

Now, the question is why does AP block the traffic only in the wireless
direction.

Any hint on solving this issue?
Is this a bug on linksys?

After chatting with linksys support online, they could not give me a
solution and they did not consider
it a bug!!

Regards,
Pedro Pereira

(E-Mail Removed) hath wroth:

>AP1 <-> HUB <-> AP2 <-> Laptop
> |
> PC
>
>Here is when I start to have problems.
>The connection to AP2 is fine and I can ping it. But, I cannot ping the
>AP1 or the wire PC.
>This problem happens during 15 minutes, and after this time period the
>connectivity is back.
>It seems that it is a problem with an agingtime that blocks the AP from
>forwarding traffic.
>
>After putting a sniffer in the laptop and the PC, I could tell that the
>traffic is forwarded
>by the AP from the wireless to the wire but the traffic from the wire
>to the PC is not forwarded
>to the wireless. This means that any arp sent by the laptop is seen in
>the wire, but any arp reply
>is not sent to the Wireless.
>
>Now, the question is why does AP block the traffic only in the wireless
>direction.

Duh. It shouldn't do that unless it's blocking all broadcasts.

Try a few experiments. I'll assume Windoze XP SP2 Home.

1. Connect to AP2. Run:
Start -> Run -> cmd <enter>
ARP -d * (flush the entire ARP table)
Now, try to ping everything again.

2. Connect to AP1 as you did in the first case that worked. Ping
everything to be sure it's still working. Run:
ARP -a
and record the results.

Now move to AP2 and run:
ARP -s ip_address 00:aa:bb:cc:dd:ee
for AP1 and the PC exactly as it appeared in the "ARP -a" listing. You
don't need ARP broacasts if you can supply them manually.

If that works, then you've found a nasty bug in the Linksys firmware
(which you didn't specify the version). If it doesn't work, then the
problem is somewhere else, possibly a MAC address filter in the access
point.

Looking at the WAP54GP setup at:
http://www.linksysdata.com/ui/WTR54GS/
I find lots of potential probelems:

1. I notice that it supports RIP (router information protocol). Make
sure this is off as it may cause entertainment value.

2. Make sure you did *NOT* clone the MAC address of the PC or you'll
have identity problems. That works fine with a router, but gets messy
with an access point that doesn't have the WAN-LAN isolation of the
router.

3. This is the first access point I've seen that has a firewall. Turn
it off:
http://www.linksysdata.com/ui/WTR54G...5/Security.htm

4. The WAP54GP has a DHCP server. This is my guess as to the most
likely culprit. You should only have ONE DHCP server on a system.
Turn off one of the DHCP servers in either AP1 or AP2.



--
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

Hi Jeff,

Thanks a lot for your answer.
I will try the arp -s command. This could be a very good test because
it could be that the AP is blocking the arp to the wireless interface
(you never know).

The firmware that I am using is the latest one on linksys web site:
1.24 (it is the one that comes with the AP, so I never updated it)

Regarding the WAP54GP, I guess that you have mistaken it with WTR54GS.
The one I have it is a very simple Access Point, and it does not
support any features such as RIP or dhcp server.




I am quite sure that the problem is not with the arp because I can

Sorry ... hit the reply button by mistake! :-)

as I was saying, I am quite sure that the problem is not with the arp
on the PC because I am able to ping it before the connection to the AP2
and after the 15 minutes period, I can also connect.
It can be a problem with the arp table in the AP, but I cannot clear
it!

Regards,
Pedro

On 15 Mar 2006 16:48:48 -0800, "(E-Mail Removed)"
<(E-Mail Removed)> wrote:

>Regarding the WAP54GP, I guess that you have mistaken it with WTR54GS.
>The one I have it is a very simple Access Point, and it does not
>support any features such as RIP or dhcp server.

Oops. The list at:
| http://www.linksysdata.com/ui/
shows a WAP54GP2 and a WAP54GP2A-AT. Somewhat different firmware. The
WAP54GP2 seems the more reasonable guess.

So, let's go down my previous list (again):

1. It has RIP:
| http://www.linksysdata.com/ui/WRT54G...AdvRouting.htm
Make sure it's turned off.

2. It apparently does NOT do MAC address cloning, so that's not an
issue.

3. It apparently does NOT have a firewall, so that's not an issue.

4. It does have a DHCP server. Make sure there's only one DHCP
server in the system. If there's a router somewhere in your LAN, use
its DHCP server.
| http://www.linksysdata.com/ui/WRT54G...0.01/Setup.htm
This is my best guess as to the cause of the problem.


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

Hi Jeff,

The closest to my WAP54GP is
http://www.linksysdata.com/ui/WAP54G/v3/3.01/Setup.htm.

Again, this one does not have RIP or DHCP.

Pedro