Cisco – In what mode does the 2960-S IOS prompt ends with a colon “:”

ciscoswitch

QUESTION

For a Cisco 2960-S switch, when connecting on the console port, normally the prompt is:

SwitchName>

then you issue an enable command and end-up with a prompt like:

SwitchName#

However, I stumbled to diagnostic a switch which was improperly booted with this prompt:

switch:

Note that the hostname wasn't shown, switch: is the exact prompt displayed, ending with a colon. I tried finding more information about this mode so that I can understand what happened and if it will happen again, but couldn't.

ADDITIONAL CONTEXT

there was a blinking-amber light on the front panel (I must admit I did not note which one, but it was one of the top ones, I think it could be RPS)
this was following a power outage
none of the ports had any indicators ON
no command of my knowledge were recognized on that prompt
I ended-up powering off twice the switch until it booted properly again
I haven't been able to reproduce since

Best Answer

The colon indicates that you've entered the switch bootloader.

There are a few things you can do in this mode, the most popular I can think of is replacing a corrupted IOS image, which would be a good reason why you ended up there in the first place.

Related Solutions

Cisco – the NO PAYLOAD ENCRYPTION version of the IOS software

From the Cisco website:

Universal images with the universalk9_npe" designation in the image name: The strong enforcement of encryption capabilities provided by Cisco Software Activation satisfies requirements for the export of encryption capabilities. However, some countries have import requirements that require that the platform does not support any strong crypto functionality such as payload cryptography. To satisfy the import requirements of those countries, the `npe' universal image does not support any strong payload encryption. This image supports security features like Zone-Based Firewall, Intrusion Prevention through SECNPE-K9 license.

So you would use this image if you were in a country that has import restrictions on strong crypto.

Cisco IOS SNMP – When Does the ifCounterDiscontinuityTime Counter Change?

The ifCounterDiscontinuityTime is triggered when interfaces are dynamically removed from a device and then that same interface is dynamically re-added. I tested this using a loopback interface but I believe the behavior would be the same for modular interface whose existence would change based on whether or not the module was present. The steps to reproduce this are below and there is some further reading on this topic in the RFC here: https://www.rfc-editor.org/rfc/rfc2863#section-3.1.5

1. Create loopback 100 and find it's ifindex

router1#conf t
router1(config)#int loopback100
router1(config-if)#end

[user@host logs]$ snmpwalk -v 2c -c $COMMUNITY router1 .1.3.6.1.2.1.2.2.1.2 | grep Loopback
IF-MIB::ifDescr.67 = STRING: Loopback100

2. Check the current value of ifCounterDiscontinuityTime for Loopback100

[user@host logs]$ snmpwalk -v 2c -c $COMMUNITY router1 1.3.6.1.2.1.31.1.1.1.19.67
IF-MIB::ifCounterDiscontinuityTime.67 = Timeticks: (0) 0:00:00.00

3. Remove Loopback100 and check the value of ifCounterDiscontinuityTime

router1(config)#no int loopback 100

[user@host logs]$ snmpwalk -v 2c -c $COMMUNITY router1 1.3.6.1.2.1.31.1.1.1.19.67
IF-MIB::ifCounterDiscontinuityTime.67 = No Such Instance currently exists at this OID

4. Re-add Loopback100 and check the value of ifCounterDiscontinuityTime

router1(config)#int loopback 100

[user@host logs]$ snmpwalk -v 2c -c $COMMUNITY router1 1.3.6.1.2.1.31.1.1.1.19.67
IF-MIB::ifCounterDiscontinuityTime.67 = Timeticks: (111308186) 12 days, 21:11:21.86