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matej
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Mikrotik+Cisco Wireless LAN Controller problems

Fri Jul 29, 2016 11:22 am

Hello!
We've got a problem with our WiFi company network. We bought a Cisco Switch and Wireless LAN Controller (Cisco 2500 WLC) plus eight Access Point (Aironet 2700) to offer clients seamless roaming between APs. These APs work like charm (I think it's just because they are from the same vendor), but our network was at first stages built around Mikrotik devices and now we are heading several problems.

Short about our topology:
We want two WiFi networks (two SSIDs) so we made two VLANs (20,30).  The traffic from Access Points is packed inside one agregated management VLAN (10). Because of agregated link the WLAN Controller is connected to network using one LAN connection. At this point everything works and everything blinks :) (and inside this Cisco "subnetwork" I am able to ping these Cisco devices each other).

Image

BUT:

 1. first problem is the DHCP server. When it is configured on Cisco switch all WiFi clients get their IP with no problems. But when it is configured on Mikrotik the WiFi client gets the IP but when looking into Mikrotik ARP tables they have the same MAC address. The MAC address of WLAN Controller.
 2. when I try to ping Mikrotik router from Cisco switch it works. When I try to ping Cisco switch from Mikrotik it also works. But when I try to ping Mikrotik from WiFi client the client sends ARP request but is unable to get any reply from Mikrotik at all (all clients have IP address and default gateway set properly). And when I try to ping client from Mikrotik router it also doesn't work but after 2 or 3 minutes it starts work!

This is madness and we had to misconfigure something or some sort of service/protocol does not works properly between Mikrotik and Cisco. Have you ever seen something like this.

Thank you for your help!
 
 
pe1chl
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Re: Mikrotik+Cisco Wireless LAN Controller problems

Fri Jul 29, 2016 12:37 pm

We have a network like that, and it works perfectly...
Unfortunately for you, I have not configured the Cisco part of it, and I know no details about it.
But the network structure is the same as above, except that we use the MikroTik only for a VLAN connected towards internet
so the link between switch and MikroTik has been configured untagged.  That should not be different.
The clients are all visible at their original MAC address, and the whole thing works fine both on IPv4 and IPv6.

Edit: well no, it is not the same.  In our network there are 3 different VLANs towards the AP's, and the network traffic from AP to
router is not in the management VLAN but is directly in a separate VLAN.   That is probably the crucial difference.
 
matej
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Re: Mikrotik+Cisco Wireless LAN Controller problems

Tue Aug 02, 2016 9:55 am

PARTIAL SOLUTION:
Well, we found that we had several problems under one roof. And we overcame it by using brute force techniques (very time-consuming...)
  1. all AP should be connected through Trunk BUT with a native VLAN configured. In our case it is trunk with native VLAN 10.
  2. we changed ARP cache timeout on Cisco Switch to 20 sec.
  3. we made DHCP server on Mikrotik BUT we also had to configure Cisco Switch as DHCP Relay Agent.
  4. the most important thing is that we change AP mode to flexconnect technology, so all APs are autonomous but we lost advanced roaming feature provided by Wireless LAN Controller. Now, all WiFi clients manage their connection, itself. This is very buggy because of bad implementation of roaming in today's WiFi chips.
  5. we flashed the WLC to newest version...
  6. we turned off VTP prunning on Cisco switch. Maybe this was the main cause of that undefined behavior of ping.
So simple...
 
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alexfarias
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Re: Mikrotik+Cisco Wireless LAN Controller problems

Tue Mar 28, 2023 6:41 pm

Hi...
The thing is that these cloned mac that you see on your arp table are from the port that mikrotik is connected.
I've got similar problem, and we managed to solve it just changing the trunk mode port that lead to mikrotik to access mode...
So, that way the DHCP from mikrotik could delivery the ip's to clientes and recorded their macaddress on ar table.

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