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Optical monitoring not possible on ports with link down?

Contributor III

Am I missing something or the optical monitoring only works when the link is up? I am trying to troubleshoot some fiber connections which were unreliable / not coming up and when I use the `show optical-monitor x/y/z` command, I get nothing. Just comes back to the prompt.

If the same port with the same optical module has link, then I do get a proper readout of the optical monitor command (tx power / rx power / temps / current).

Being able to monitor a non-working link is a pretty basic thing to do to be honest and having access to DDM/DOM/optical monitoring of down links lets you figure out if you have, for example, a broken fiber in one direction, a mis-plugged rx/tx pair, etc.

Is there any way to monitor the DDM/optical parameters while the link is down?

Thanks in advance!


RUCKUS Team Member

Hi Diego,

The optical monitor shows signal levels, but will only show statistics if the port is up:

device(config)# show optic 2/1/1
Port Temperature Tx Power Rx Power Tx Bias Current
2/1/1 32.2578 C -002.5157 dBm -002.8091 dBm 5.966 mA
Normal Normal Normal Normal

If Signal is not correct and media type and fiber not right type link will not come up.
You need to check show media e x/y/z on both side make sure fiber is of right type.

Hope this helps.

If you need further help please open a  ticket and work with our TAC team.



View solution in original post


RUCKUS Team Member

Hi Diego,

Like i said working as designed here is a lab snippet:

CORE-ICX-7850-10G(config)#sh optic  2/1/20
 Port   Temperature    Voltage       Tx Power      Rx Power    Tx Bias Current
2/1/20   20.0468 C    3.2566 volts  -002.4336 dBm   -003.2605 dBm     5.600 mA
        Normal          Normal       Normal         Normal         Normal

CORE-ICX-7850-10G(config)#int e 2/1/20

CORE-ICX-7850-10G(config-if-e25000-2/1/20)#sh optic 2/1/20


It shows nothing when port is down.

Hope this clarifies.



Hi Hashim,

I can appreciate it is "as designed". What Im saying is that it's poorly designed. 

Also, in your case, you are shutting down the port which is not the same. In my case, the port is ADMIN UP (enabled) but operationally down due to a faulty fiber plant. Having DOM working when the port is operationally down (but admin up) can help troubleshooting greatly.

I will open an RFE 

best regards

RUCKUS Team Member

Also i asked you paste the output of your problem switch but i do not yet see it

show media x/y/z

show interface e x/y/z

show license

show version

Please share



New Contributor III


I have ICX-7150 with 08.0.95a.... can you please help me to configure the DHCP server on this switch?


Hi Claude,

Hope you are doing great.

From  the DHCP guide:

Configuring the DHCP server and creating an address pool

Perform the following steps to configure the DHCP server. Before you can configure the various DHCP server options, you must create an addresspool on your FastIron device.

1.Enter global configuration mode by issuing the configure terminal command.device# configure terminal

2.Enable the DHCP server.

device(config)# ip dhcp-server enable

3.Create a DHCP server address pool.

device(config)# ip dhcp-server pool cabo

4.Configure the DHCP server address pool.

device(config-dhcp-cabo)# network

device(config-dhcp-cabo)# domain-name

device(config-dhcp-cabo)# dns-server

device(config-dhcp-cabo)# netbios-name-server

device(config-dhcp-cabo)# lease 0 0 5

5.To disable DHCP, enter the no ip ip dhcp-server enable command.

device(config)# no ip dhcp-server enable

6.Use the clear ip dhcp-server binding command to delete a specific lease or all lease entries from the lease binding database.

device(config)# clear ip dhcp-server binding

*The asterisk used in the example above clears all the IP addresses.

Hope this helps.