Cisco CBS-350 DHCP issue + available in other networks

[Stephan15]

Hi There,

we now have 2 of these devices in our company and both behave the same.

DHCP leases will not be deleted automatically. So we are ending up full of expired leasees until no receives a new IP.

Another issue is that also both switches are not available from other networks. is there a setting for it?

Both are with the newest firmware (status 04.03.2024)

thanks a lot

stephan

[marce1000]

       - Preferably use a (separate) appliance for DHCP services and or not on a switch , 

 M.

[liviu.gheorghe]

Hello @Stephan15 ,

do you have the lease <time> command in your DHCP configuration? Can you share the switch configuration?

[Stephan15]

Lease time is set to 45days.

I´m using the GUI as i´m not an command line exptert.

[liviu.gheorghe]

It should be 4 or 8 hours.

[Stephan15]

But that will cause the described issue. The lease will STAY and block other clilents to receive that IP.

[liviu.gheorghe]

I understand. You are using an extremely long lease time to avoid the issue with expired leases not being removed. This can be an effective workaround if you don't have more than 250 devices needing DHCP assigned addresses. If this is the case you can set the lease time even longer.

What is the exact model of your CBS 350 and what is the exact firmware version? It seems like a bug to me - I will try to find it based on the model and software version.

[Stephan15]

Yes correct. Thanks

CBS350-8T-E-2G 8-Port Gigabit Managed Switch
Firmware Version (Active Image): 3.3.0.16

[liviu.gheorghe]

I would recommend upgrading to CBS350 Firmware Image Release 3.4.0.17 which is the latest. After the upgrade, test if the issue is resolved or not. To be able to test more quickly, you can lower the lease time to 10 minutes for example.

I've seen issues resolved after an upgrade on the CBS in the past. If the issue is not resolved, we can proceed forward identifying the bug which is causing the issue.

[Stephan15]

Thanks for the hint with the update. installed. but leases are going to expire again without beeing removed from the system. Is there a setting we need to be set so that it will clear the expired leases?

[liviu.gheorghe]

The only option that I know off for the removal of expired leases is the one you are using already - lease <time>.

I did a search for a possible bug matching the parameters of your issue, but didn't find any.

I would strongly suggest:

• doing the upgrade to the lates available firmware - 3.4.0.17
• test to see if issue exists after upgrade, lowering the lease time while testing
• if you don't have a problem with the number of IP's - being less than the number of hosts on the LAN - you can set the lease time to infinity
• if nothing works and issue still present, open a TAC case

Hope this helps.

[Stephan15]

The upgrade has been installed -  issue still persist. lease to infinity, hmmm.....

TAC case can only be opend up with a service contract which we don´t have for this small switches..

[liviu.gheorghe]

I'm sorry to hear that the upgrade didn't solve the issue you are facing.

About the TAC case, you may be in luck - 

as per Cisco documentation, you don't need a support contract to access the technical support for your CBS350:

Q. What is the warranty?

A. Cisco Business switches come with a Limited Lifetime (CBS350, CBS250 and CBS110 series) or 3-year warranty (CBS220 series). If there are any hardware defects, Cisco will replace the product upon receipt of the defective device. In addition, the warranty includes free access to technical support during local business hours, 8 hours per day, 5 days per week, for a period of 1 year from the original date of purchase. Software bug fixes are available for the life of the products.

Cisco Business 350 Series Managed Switches come with an Enhanced Limited Lifetime Warranty (ELLW), which provides next-business-day advance replacement where available in addition to the standard coverage in LLW.

Product warranty terms and other information applicable to Cisco Business products are available at https://www.cisco.com/go/warranty.

I think you can go ahead and open a TAC case if your switch is not older than 1 year.

Hope this helps.