The CIMC is Cisco’s answer to lights-out management for UCS servers, including the UCS servers that house the APICs. For troubleshooting the APIC, most engineers assume you must have direct console (i.e., physical access) or use the Java (or later HTTP)-based KVM Console to get true OOB access to your APIC, however, this is not the case. You can also use Serial-over-LAN (SOL) via an SSH client to access your APIC.

There are certain times when CIMC access to your APIC is absolutely critical (i.e., troubleshooting a problem, performing a factory reset). During these times, you can access your APIC via CIMC by using the KVM console, which requires Java (or in later versions HTTP), or by enabling serial-over-lan support on your CIMC and using an SSH client.

For anyone that has used Java to access the KVM console, you’ve all experienced some level of frustration with incorrect versions of Java, or security mechanisms blocking access, usually during the most critical times.

Serial over LAN (SoL) is a mechanism that enables the input and output of the serial port of a managed system to be redirected via an SSH session over IP. SoL provides a means of reaching the host console via CIMC.

If you are interested in upgrading your CIMC to allow for HTTP-based KVM, check out the Upgrading the CIMC for your APIC article here!

Enabling Serial-over-Lan for your CIMC

To use SOL via an SSH Client, you will first have to enable it on your CIMC. To do this, SSH to your CIMC IP address and login;

Server# scope sol
Server /sol # set enabled yes
Server /sol *# set baud-rate 115200
Server /sol *# commit
Server /sol *#
Server /sol # show
Enabled Baud Rate(bps)  
------- --------------- 
yes     115200    

Server /sol #

Once you have Serial-over-LAN enabled, you can connect to the underlying host on the CIMC (i.e., your APIC).

Server# connect host
CISCO Serial Over LAN:
Close Network Connection to Exit

Application Policy Infrastructure Controller
apic2 login: