---[Background]---

As part of troubleshooting the initial Dante problems, I found that the
Cisco SG300 Switch in the tech booth no longer responded to the new
credentials I had assigned weeks ago. So in order to continue I needed
to reset the credentials on that device. Without being able to login
through the Web interface, I needed to connect via the console port
using a rollover cable and the putty serial terminal on my laptop.

When I tried that, it appeared that the console interface had been
disabled. So I was forced to perform a factor reset which would reset
the credentials, but also lose all configuration settings reverting
them to the factory defaults. That appeared to be the only course.

Note that much of the steps and issues mentioned below apply to the
other switches to some degree. The differences are in the user interface
and product implmintations of switch technology.


---[Connecting to the Console port]---

When I plugged in the rollover cable I was able to verify it was
recognized by my system using the command below. 'Prolific' is them
rollover cable.

$ sudo lsusb
Bus 002 Device 005: ID 0a5c:5800 Broadcom Corp. BCM5880 Secure Applications Processor
Bus 002 Device 004: ID 046d:c52b Logitech, Inc. Unifying Receiver
Bus 002 Device 006: ID 067b:2303 Prolific Technology, Inc. PL2303 Serial Port
Bus 002 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 003: ID 05ca:181c Ricoh Co., Ltd
Bus 001 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
ben@benbellamy:~$

$ sudo modprobe usbserial vendor=0x067b product=0x2303

$ sudo dmesg
[  233.781368] usb 2-1.3: new full-speed USB device number 6 using ehci-pci
[  233.890834] usb 2-1.3: New USB device found, idVendor=067b, idProduct=2303, bcdDevice= 4.00
[  233.890841] usb 2-1.3: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[  233.890845] usb 2-1.3: Product: USB-Serial Controller D
[  233.890848] usb 2-1.3: Manufacturer: Prolific Technology Inc.
[  233.891421] pl2303 2-1.3:1.0: pl2303 converter detected
[  233.893893] usb 2-1.3: pl2303 converter now attached to ttyUSB0
[  498.699228] e1000e 0000:00:19.0 eth0: NIC Link is Up 1000 Mbps Full Duplex, Flow Control: None
[  498.699297] IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
ben@benbellamy:~$

idVendor=067b, idProduct=2303,

But when I rebooted the switch (by unplugging it's AC cable and plugging
it back in - it does not have a power switch - I would get this error. I
never saw any output on my screen.

Putty error message:
Unable to open connection to /dev/ttyUSB0:
Unable to open serial port

I spent about 45 minutes on this problem making no progress. So I decided to
move ahead with a factory reset of the device.


---[Factory Reset]---

To use the Reset button to reboot or reset the managed switch, do the following:

• To reboot the managed switch, press the Reset button for less than 10 seconds.

• To restore the managed switch configuration to the factory default settings:

    1. Disconnect the managed switch from the network or disable all DHCP servers
            on your network.

    2. With the power on, press-and-hold the Reset button for more than 10 seconds.

This worked just fine.


---[Connecting to the reset Switch]---

The Cisco SG300 Switch in the tech booth us had been using 10.32.10.20. But there was
some question about what IP it would have when it rebooted. Either a DHCP assigned
address or the default of 192.168.1.254 or 192.168.2.254. Seems easy enough, but no.

I changed my laptop to 192.168.1.10/24 but got no response. So I changed to
192.168.2.10/24 and still got no response. I then went to DHCP and tried 10.32.10.20,
and got no response. But the other devices continued to work and have access to the
Internet.

So I ran arpscan and identified the only Cisco device and connected to it. It was
in fact the SG300 switch. It had taken a DHCP address (which I had suspected, but
none of the documentation mentioned that.

I used the following commands to change my IP address:

$ sudo   ifconfig eth0 192.168.2.10 netmask 255.255.255.0
$ sudo    route add default gw 10.32.10.

$ sudo   ifconfig eth0 10.32.10.233 netmask 255.255.255.0
$ sudo    route add default gw 10.32.10.


---[Initial Settings]---

First I logged in with the default credentials;
    ID: cisco
    PW: cisco

Then I logged out and back in to verify the new credentials.

Then I configured the switch to use 10.32.10.20/24 as it's IP. After making
a change you need to click the save button. In this case, after the save
was performed, the device 'rebooted' to its new IP and the browser was able
to reconnect just fine.


---[Firmware]---
The firmware was 6 years old and there had been several updates since then.
So I first downloaded the currently installed firmware so I had it on hand.

Firmware active image
As of 08.19.20 the Firmware was: 1.4.0.88
Sx300_FW_Boot_1.4.0.88.zip
14-Aug-2014
https://software.cisco.com/download/home/283019611/type/282463181/release/1.4.0.88?i=!pp

Then I downloaded and installed the latest Firmware. 19.08.2020
On 08.19.20 it was updated to 1.4.11.5
https://software.cisco.com/download/home/283019611/type/282463181/release/1.4.11.5?i=!pp
sx300_fw-14115.ros
18-Jun-2020

I then rebooted the switch and it seemed to function properly.

As I mentioned at the beginning, this issue was discovered as part of
working on the multicast flooding Dante is doing. So now that this
switch is assisable and up to date, and I returning to that issue.