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What happens when RX power is down & TX is up in 10G interface in Cisco 3850 Switch

btech.vinoth
Level 1
Level 1

Hi 

 Recently we have faced an issue in cisco switch 3850 series where Rx is down and Tx is up in 10G interface. 

 During this scenario , the interface is down and line protocol also down but the peer end connection was UP. 

TenGigabitEthernet2/1/3 is down, line protocol is down (notconnect)

 

My doubt : are we still sending any traffic in TX to the destination, the reason why for asking is,  from peer point of view 

RX is up and Tx is down due which interface was up and line protocol also up.

In my end,  switch port is down and peer end switch port is up which leads to the outage. 

 

Can anyone who has the idea of the above situation can help me 

 

 

Below is the transceiver power status of the interface :: 

#show interfaces tenGigabitEthernet 2/1/3

                                           Optical   Optical

           Temperature  Voltage  Current   Tx Power  Rx Power

Port       (Celsius)    (Volts)     (mA)        (dBm)     (dBm)

---------  -----------  -------  --------  --------  --------

Te2/1/3      46.3       3.22       39.4          2.4      -0.0

 

 

  

 

 

4 Replies 4

marce1000
VIP
VIP

 

 - The switch won't send or receive data when the line protocol is down; but you can verify this by examining the interface counters (periodically).

M.



-- ' 'Good body every evening' ' this sentence was once spotted on a logo at the entrance of a Weight Watchers Club !

I understand that switch won't send any data. 

From my end, Tx has some power ( 2.4dBm) which is RX for the destination node and it thinks the link is okay and status is up. 

is there any possible configuration,  when RX power is down automatically brings the Tx power also down from cisco sw 3850.

 

 

When Rx & Tx signal is 0 dBm from my end then automatically destination node brings the link down, when link down in both sides it will trigger auto failover.  

 

 

 

 

 

 

 

>...is there any possible configuration,  when RX power is down automatically brings the Tx power also down from cisco sw 3850.

 - There's no reason to interact with 'the partner' at all, at that level, from the switch point of view. Either the link is up or down.

M.



-- ' 'Good body every evening' ' this sentence was once spotted on a logo at the entrance of a Weight Watchers Club !

Hello,

Not sure UDLD aggressive mode could help in your case. If the link state of the port is determined to be bi-directional and the UDLD information times out while the link on the port is still up, UDLD tries to re-establish the state of the port. If not successful, the port is put into the errdisable state.

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