Summary
There is a limitation on the 4120 where a port transitioning between 10 Mbps speed and other speeds may transmit corrupted packets, resulting in dropped packets by the link partner even though the port is operationally up. A switch reboot is required to recover from this condition.
Products Affected
4120 Series
Software Affected
N/A
Impact
Port transitioning between 10 Mbps speed and other speeds can enter failure state where it transmits corrupted packets and the only way to recover is to reboot the switch.
Symptoms
When a 4120 port transitions from 10 Mbps to another speed, the port remains operationally up and can receive packets, but transmitted packets are corrupted and are dropped by the link partner.
Solution
- For port operation only at 10 Mbps speeds and auto-negotiation, set the auto-negotiation speed capability to 10 Mbps only using “configure ports <port_list> auto on speed 10 duplex full”
- For port operation at 10 Mbps speeds and no auto-negotiation, disable auto-negotiation and set port speed to 10 Mbps and duplex to full using “configure ports <port_list> auto off speed 10 duplex full” Note: Half-duplex is not supported on 4120.
- For port operation at 100 Mbps, 1 Gbps and 2.5 Gbps speeds and auto-negotiation, set the auto-negotiation speed capability to desired speed as shown below: (Note that the EXOS 33.6.1 release (and later) as well as post 32.7.3-patch1-54 releases will include changes which remove 10 Mbps from the default advertised abilities and prevent the need to issue the below commands):
configure ports <port_list> auto off speed 100 duplex full
configure ports <port_list> auto on speed 100 duplex full
configure ports <port_list> auto on speed 1000 duplex full
configure ports <port_list> auto on speed 2500 duplex full
Please see the full field notice release here for more details and future updates.
