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New Member

Problems between Moxa and Cisco


I have problems in my Cisco network until I connected some Moxa devices.

This Moxa are models EDS-316 and EDS-208

My principal trouble is the traffic UDP. Suddently the network don't permit the traffic UDP in VLAN where are connected Moxa devices.

During an hour the Moxa can send TCP traffic, but can't send UDP. If a Moxa device is unplugged from network, all devices connected to him can work offile from principal network, but if I plugg again the Moxa is like disable.

After one hour (more or less) the system restart all functions and work fine.

I catch the logs from TXerrorsInPorts and all the ports where is connected a Moxa have errors all time.

I don't know which is the problem, but I think that problem is in negotiation from Moxa to Cisco.

This is the configuration from a port where is connected a Moxa:

             interface FastEthernet0/23

                description Encajadora 10

                switchport access vlan 119

                switchport trunk encapsulation dot1q

                switchport trunk native vlan 119

                switchport mode trunk

                power inline never

                spanning-tree portfast trunk

Someone have similars problems?


  • LAN Switching and Routing
Everyone's tags (1)
New Member

Re: Problems between Moxa and Cisco


The EDS-316 and the EDS-208 are both unmanaged switches.  As switches only operate in layer 2, switches do not differentiate between UDP or TCP that is found on layer 4 of the OSI model.  Other issues that you may be having is the fact that you are using spanning tree and VLANs with an unmanaged switch.  Spanning tree BPDU (Bridge Protocol Data Units) will forward just fine with using an unmanaged switch, but the fact that the switch will not actively participate in spanning tree will lead to a whole host of issues, that usually will result in very slow convergence times.

As stated, VLANs is a concerns on unmanaged switches.  These two switches support the latest ethernet standard and thus will forward VLAN frames with the added 4 bytes without issue.  But as this is an unmanaged switch, it will not tag or untag VLANs, thus it will only work if the edge devices connected to the switch are VLAN aware, or if you have a managed switch on the other end.

My recommendation is to use the Moxa EDS-400 or 500 series switches as both these series are managed switches that support dot1q VLANs as well as RSTP and MSTP.  These switches also have the full industrial ratings that the 300 series has and are very easy to program and configure. 

New Member

Hi Justiz,

Hi Justiz,

i think we have nearly the Same Problems. We have round about 20x des-208 moxa switches in an 4x 2 3750 STack LAN. The Moxas are redundant connected over flexlink.

Devices Connected to the moxa switches are not stabile Reachable. We see errors on the cisco Ports where moxa switches  are connected. In the Network we have multicast and icmp Troubles.

Do you solved your Problems?

regards Lenny