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Intermittent Network Disconnection | Cisco WS-C2960X Switches & SG 300 Series Switches



Expecting your valuable support to find root cause of intermittent /random network disconnection happening for intervlan (intervlan routing handled by firewall) & intra vlan communication.

Please find the attachment.

01. Network architecture.

02. All switches details (WS-C2960X) acting as distribution switches (C2960X switches not in stack), SG300serirs acting as edge switches along with IOS /Software version, STP details, etc.


We have noticed following problem.


01. Intermittent network disconnection for intervlan communication (from valn 1 to internet or other vlans like vlan 15, 21, etc and vice versa).

02. Intermittent network disconnection for intra-vlan communication (example: printers to SMTP server both are in vlan 1).


Earlier all our devices (servers, printer/scanners, user machines are in VLan1), 1 month back we have installed new firewall and configured multiple vlans and moved few users to new vlan (example: vlan21). Still ost of users and servers, printers are in VLAN1.

Unfortunately few days back we are observing network disconnection for intervlan as well as intra vlan communication.

We didnt find any root cause for these issues.

Kindly help us to investigate and rectify the same.


Network architecture & all switches details are attached herewith for reference.

Expecting valuable technical help from here. 








3 Replies 3


I don't have an answer but there is newer firmware for the SG300-28 switch and the SG350-52P switch.  You might want to try the newer firmware first.

Hi leecoxhouse1,

Thanbks for your valuable suggestions.

FYKI, We have successfully upgraded firmware/boot code & recommended configuration on SG300-28 Switches.

Unfortunately unable to complete the firmware upgradation on SG350-52P Switch. We have downloaded firmware Image (image_tesla_hybrid_2.5.0.92_release_cisco_signed.bin) and tried to uploaded image using web GUI (Administration--> File Management --> Firmware Operatio--> Update Firmware, HTTPS/HTTPS and browse the file), image was trying to upload (Kindly refer the attachment) and after sometime switch automatically rebooted and booted with old firmware ( While uploading image we didn’t find file transfer progress (how we transfer image file using TFTP to SG300-28 model switches).
Please find the available images (old) details on switch. Kindly help us on this.

Active-image: flash://system/images/image1.bin
MD5 Digest: 6f5be217100f34929986f2e93dd2d5e9
Date: 31-May-2018
Time: 02:39:58
Inactive-image: flash://system/images/_image1.bin
MD5 Digest: 6f5be217100f34929986f2e93dd2d5e9
Date: 31-May-2018
Time: 02:39:58

Hi leecoxhouse1,

FYKI, Now we successfully upgraded SG350-52P firmware to using TFTP.
Thanks for your valuable inputs and support, We will observe the network disconnection and will let u know is anything.




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