Tech Blog

NetFlow setup for 3750x with C3KX-SM-10G

The Cisco 3750x switch does not support NetFlow natively, but the C3KX-SM-10G module has ASICs that support NetFlow.  With the C3KX-SM-10G module, NetFlow can only be run on the 4 interfaces in the module — this does not add NetFlow on the entire switch.

It is however possible to capture the switch’s traffic and port mirror (SPAN) it over to one of the C3KX-SM-10G interfaces so that it can be exported for NetFlow.  The problem is that in order to mirror traffic to a port and export NetFlow, the port must be in an UP state.  In order to force the port up we took an LC fiber patch cable and split apart the plastic end and pulled the cable apart so that we had 2 single fiber strands.  Then we plugged in an SFP and connected the port into itself by looping the single fiber back to the same SFP.  Use caution with this as it will create a loop — it might be better to setup the mirror first as it will put the port in an UP/DOWN state that I’ll mention later.

LC Patch Cable Loop
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Barracuda ADC Load Balancer with OWA – Login loop

We had a problem with Barracuda’s ADC load balancer and Outlook Web App for Exchange 2013.  The user would get to the OWA login screen and login only to be brought back to the login screen again in an endless loop.  We were using the “Instant SSL” service type as described in the following Barracuda document:

The problem was that “Rewrite Support” was enabled on the service.  Disabling this allowed the users to login without problem.


Exchange 2013 DAG: Can’t add a database copy – “Seeding operation failed”

We had an issue when attempting to add a database copy for any mailbox databases in a new DAG.  We received one of the following errors every time, regardless of the source or destination server.

The seeding operation failed. Error: An error occurred while running prerequisite checks. Error: The specified database isn’t configured for replication and therefore cannot be used to perform seed operations.

The seeding operation failed. Error: An error occurred while performing the seed operation. Error: An error occurred while processing a request on server ‘MailboxServerName’. Error: Database ‘6060c9ac-363a-4e52-a02e-ba749625e8ea’ was not active on source server ‘MailboxServerName’. [Database: Test3, Server:]


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Ubiquiti AP powers up & reachable via wifi, but no link on LAN

We’ve seen this happen twice recently with different customers so thought we should post our solution.  We have seen where a Ubiquiti AP (NanoBeam & NanoStation) will power up via the power injector and the unit is reachable via wireless, but there is no link light on the switch or to a laptop plugged directly in.  In both cases the units were mounted up on a roof, so we first replaced the cables from the injector to the switch but nothing changed.  We found we had to either re-terminate the RJ45 ends on the cable going from the injector up to the roof or replace the cable completely before it started working again.  The cable end or cable itself was damaged so that it wouldn’t allow link, but PoE passed through.

Ubiquiti with PoE Injector


Adding PoE to a Cisco 890 Series Router – (C891FW-A-K9)

In order to add PoE to an 891 router, the datasheet says you need “800-IL-PM-4 with 125W PSU.”  I had to use the Cisco Commerce Workspace to generate a config starting with the 800-IL-PM-4= part number and then added the 125W power supply there.  The following is what was shipped:

The 800-IL-PM-4= part is a daughter-card that is installed onto the motherboard of the 891 router.

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