Cisco 1815i AP, Mobility Express and WiFi extender

[SonusFaber]

Good morning,

at home I have some 1815i AP with Mobility Express. Everything is quite fine.
The router where the provider's fiber arrives host also the DHCP server.
I need to bring the WiFi downstair for 1 device only and the WiFi is poor, so I found 2 different non Cisco WiFi extender unused.
I configured both the extender on the home SSID generated by the Cisco; extenders perfectly connect, but clients connected to the extenders DO NOT get any IP address. Manually assigning the IP address it is perfect. Unfortunately the device I need to connect does not support fixed IP on WiFi side.
So... the extenders get their own IP from the DHCP as soon as they join to the Cisco SSID, but the IP request they start do not flow from the Cisco AP to the DHCP server.
Switching on an AP different than Cisco works, so the problem is in the Cisco configuration.

Everything is on the very same VLAN, the default one... Cisco AP, DHCP, router, etc.

So, the question: is there something I can do on Cisco AP to let a WiFi extender to obation the IP from the DHCP?

[SonusFaber]

Hello.

Yesterday evening I performed other test with another WiFi extender, this one from Huawey.
The behaviour is always the same and, in other words:
- Cisco AP accept DHCP requests coming from its clients and broadcast them over the network and so the DHCP server can answer
- Cisco AP accept the DHCP request coming from the WiFi extender
- Cisco AP DOES NOT accept DHCP requests coming from the clients attached to the extender... or it accepts but does not forward to the DHCP server

According to you, is there something I can configure on the AP \ Mobility Express to allow such traffic?

Thanks

[Rich R]

https://community.cisco.com/t5/wireless/using-a-range-extender-with-wlc-lwap/td-p/1799992 
Note that Nicholas is a TAC wireless specialist.

[SonusFaber]

Thanks for your contribution.

I made another test not using a WiFi extender but with a WiFi-Wired-Ethernet adapter.
In such case I am not extending the WiFi signal (I know it is something bad... I know) but I am trying to connect a remote device using its wired ethernet with a WiFi-Ethernet adapter.

In this case, again, the adapter get the IP through the Cisco AP and the DHCP server running on my router, but the device wired to it CAN NOT.

I can not understand if Nicholas answer sounds like "it can not work at all" or it is "just" a very bad idea but it can bypassed.

thanks

[Rich R]

My understanding is "it can not work at all".
What you're trying to do is generally referred to as workgroup bridge which can be done with Cisco APs only:
https://www.cisco.com/c/en/us/td/docs/wireless/controller/8-10/config-guide/b_cg810/workgroup_bridges.html

Have you thought about using a powerline extender?

[Scott Fella]

@Rich R is right as it doesn't work 99.99% unless its another Cisco ap and is supported.... I personally hated working with extenders back in the day's because they seem to only work with consumer equipment and always seemed to have to get rebooted every so often.  No way of running a cable and connecting an ap to that cable to extend your wireless with another 1815i?

[SonusFaber]

OK, so it means that Cisco INTENTIONALLY blocks such DHCP requests ?

I can not use powerline extenders, since where I have Cisco AP's it is my home\office and where I need to have the network is another place nearby where I have the inverters of the photovoltaic panels and these two places are not connected each others.. I need to do some digging...

So... at the end of the story... if it does not work... I will bring an Ethernet cable using the old telephon pipe where the twisted pair is still inside together with the optic fiber of the local telco provider... I do not expect they will inspect it for the next 50 years!

Anyway... I understand Cisco position... and i understand why the default config is to block such traffic... but at the same I can not understand why any end user could not change the behaviour.

Thanks.

[Scott Fella]

I don't think it's "they block it", more how vendors implement the standards on these consumer bridges.  Other vendors don't support bridging on their wireless either, so it's just looking for another option.  I used WGB at my old home and it sucked, neverl liked doing that.  At my home now, I took the phone lines that were ran with ethernet cable and converted then to RJ45.  All my ap's at home are connected with ethernet and I would never look at other options, besides mesh.

[SonusFaber]

Hello

first of all thanks for the precious support, so far.
To investigate a bit more, I installed VMWare on a PC and loaded a simple virtual machine.
The PC connects to the Cisco AP, associating to the SSID and getting the IP address via the DHCP that runs on the router.
On the other hand, the VM bind to the same WiFi card, DOES NOT get any IP address and it works only using a fixed IP.

In this test I am not using the WiFi extender at all, but the problem is the same as the one with the extender.

I understood that with the standard configuration running on my Cisco (1815 + Mobility Express) i can have only 1 IP for each MAC address

Reading some documents on the community, I understand that the one of the extender and the one of VMare are 2 problems with more or less the same root cause.

Am I wrong?

[Scott Fella]

Well, when you are talking about VMware virtual machines that are bridged, that is a different story.  You need to enable passive client so that the host and virtual machine can have connectivity to the network.  With this disabled (by default) only one will have a connection which makes either the host or the vm unusable with no network.

Just search for "Cisco WLC passive client"
https://www.cisco.com/c/en/us/td/docs/wireless/controller/7-6/configuration-guide/b_cg76/b_cg76_chapter_01100000.html

[SonusFaber]

OK, but imagine for a while the PC associated to the Cisco AP like the extender
And the virtual machine inside the PC like a client trying to associate to the extender.

Am I wrong?

[Scott Fella]

It is somewhat... because you will be passing multiple Mac address when using am extender/bridge.  That is why there is specific requirements on using a WGB vs a 3rd party ap/bridge.  Hypervisors are so much better at controlling the environment and building internal networks.

I can't blame you for trying... heck I use to do the same things a while back.

[SonusFaber]

Having said that... the solution to have an extender working is the same as the one that solves the problem of mutiple VM's inside the same PC associated to the Cisco AP ?

[Scott Fella]

I don't think so, but again, what you are testing proves that.  I run virtual machines on my MacBooks that are bridged with no issues, I also have some old wireless bridges from Buffalo and Linksys that I use to use with autonomous access points and that worked, but never when I had started using controllers.  With controllers, I have tested and used Mesh which I think works well as long as there is no attenuation between the root ap and the mesh ap.  Same concept as the Orbi and other vendors home wireless that are out there now.