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New Member

Cannot ping wireless bridge from host to wireless bridge

Hello,

I have the following topo:

WIndows 7 PC 192.168.0.2 --  Cisco 3700 switch  -gbic-fiber link- AR80x BridgeWave wireless bridge management ip:192.168.0.11  <-z-wireless conn. -> remote BridgeWave wireless bridge - switch - remote LAN.


Cisco 3700:

All ports on vlan1.

All access ports.

When I try to ping from pc 192.168.0.2 to wireless bridge 192.168.0.11, ping times out.

I checked physical connection, i.e. ethernet cable to pc, fiber cable and connections, gbic connections, fiber tx and rx etc.  All is ok.

I checked the arp cache on my Windows PC (arp -a), and was NOT getting an arp entry for the wireless bridge - 192.168.0.11.

I checked the Forwarding Table in the switch, and there was no dynamic arp entry for the gbic port!!

Thus, I created a static arp entry in my pc that mapped wireless bridge - 192.168.0.11 to its MAC.

Thus, I also created a static forwarding entry in the switch that specifies that the wireless bridge MAC exists off the GBIC port.

After I do this, it all works!

So I did a sniffer trace and mirrored the wireless bridge gbic port to a pc that had wireshark running on it.

I took the static arp entry out of the pc and the static forwarding entry from the switch.

I then ran a constant ping from the 192.168.0.2 pc to wireless bridge- 192.168.0.11.   ping 192.168.0.11 -t

No ping responses, as expected at this time, as it doesnt work unless I have static arp on Windows PC and static forward entry in switch to Wireless Bridge.

I looked at the sniffer trace, and noticed that arp requests were being forward out of the gbic port to the wireless bridge, as it should do.

I did NOT see any arp responses from the wireless bridge.

So this got me to thinking that maybe it is some type of default security configuration on the wireless bridge that prevents it from sending arp responses.

So I readded the static arp on the pc and the static forward entry on the switch, so I could connect to the wireless bridge.

I www'd to the wireless bridge and did not see anything that indicates that you can disable arp on it.

Now here is the very very strange thing,

Without any static arp or static forwarding entries, a pc connected to a port that the gbic/wireless bridge mirrors to, is able to ping the wireless bridge, and also cross the entire wireless link to the remote LAN!!!!

If this is the case, then an arp response must come from the Wireless Bridge for me to be able to ping it without any static arp or static forwarding entries! 

Somehow it appears that the wireless bridge may actually be sending arp responses, but the switch doesn't "see" them as they may not be RFC-compliant...no matter how remote a possibility this seems...but I cannot think of anything else that could be causing this issue at this time.

And the same goes for the wireshark sniffer; maybe the sniffer does not recognize/see the ARP response from the wireless bridge, and thus does not display it in the packet capture.

But then this leaves the question, if I mirror the gbic/wireless bridge to a pc on another port, and that pc can cross the wireless bridge and communicate with other servers across the wireless lan, then the wireless bridge is probably not the culprit.

Thus, I think the switch somehow is not creating forwarding table entries for any packets that come into that interface over the wireless bridged network.

Also, all other ports on the switch are able to create dynamic arp entries.

Note that I did try different ethernet cables and two different gbics.

This has really got me stumped!!!

Everyone's tags (5)
4 REPLIES
VIP Super Bronze

Cannot ping wireless bridge from host to wireless bridge

Hi,

Can you post "sh run" from the 3750?

Are all your devices in the same vlan/subnet?

Are all the ports configured as access ports?

What happens if you put all your devices in a different vlan (vlan 10)?

Reza

New Member

Cannot ping wireless bridge from host to wireless bridge

Hi Reza,

Can you post "sh run" from the 3750? yes

Are all your devices in the same vlan/subnet?  yes, vlan 1

Are all the ports configured as access ports?  yes

What happens if you put all your devices in a different vlan (vlan 10)?  I can try that.

New Member

Re: Cannot ping wireless bridge from host to wireless bridge

Did this get resolved? I am having the same issue with a wireless bridge between two WAP-200E's.

Sent from Cisco Technical Support iPhone App

New Member

Re: Cannot ping wireless bridge from host to wireless bridge

Nevermind. I just resolved this myself by changing the SSID and channel from 3 to 10 in both WAPs. It now works.

Sent from Cisco Technical Support iPhone App

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