Catalyst 3750 Multi-VRF VLAN config disappear after a reload

Unanswered Question
Jun 27th, 2007


I've noticed a problem using multi-vrf on a Cat3750 with latest IOS Release 12.2.35SEE2

I've configured a VRF instance named A and on this instance I've added two VLANs: VLAN1220 and 1459, which are normal VLANs without particular settings

All is working great! via EIGRP VLAN1459 in VRF A we receive all the routes.

After saving the config and reloading the switch the system logs this error message: "

% Cannot configure VRF. Private VLAN configured on interface."

and the routing for this VRF instance is not working anymore.

Checking the running-config I've amazingly noticed that the command "ip vrf forwarding A" is not present anymore but only in VLAN1459...

in VLAN1220 all is fine. The startup-config is OK so after copying the startup-config of VLAN1459 to the running one all is returning normal...

Has anyone already noticed this strange behaviour since no PVLAN defined???



I have this problem too.
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aghaznavi Tue, 07/03/2007 - 06:19

I think this change is handled automatically during an upgrade to Cisco IOS 12.2(25)EY or later, but if a configuration is written to NVRAM and the switch is then reloaded with Cisco IOS 12.1(14)AX, the new-style configuration is lost.

thblake07 Mon, 10/22/2007 - 05:46


I can confirm the above described behaviour. We have the same problem on several 3750G-24TS-E1U with DIFFERENT IOS versions. When the switch is restarted a small part of the config is not applied to the running-config (Vlan1151, Vlan1313 missing ip vrf forwarding...).

We do not have a real solution at the moment, but will open a Case with Cisco. The Workaround for the moment is to use a different VLAN number...worked for us.

Btw: This problem seems to be Hardwarespecific (3750G-24TS-E1U). Running the same Test on a 3750G-16TD(Same IOS/mostly identical config) or WS-C3750G-24T-S(Same IOS/identical config) did not show any problems.



oguarisco Mon, 10/22/2007 - 08:58


yeap, the problem happens only with certain HW 3750 platform with the config charged and the same IOS...a very strange problem :-)

thblake07 Mon, 10/22/2007 - 23:43


just want to point you to a Bug which could possibly solve your problem. Unfortunately this doesn't work for us since we are not running BGP (using OSPF).


Externally found moderate defect: Verified (V) Cannot boot some of interface vlan with VRF configuration


VRF configuration on a vlan interface is lost and error message "% Cannot configure VRF. Private VLAN configured on interface." displayed when configuration is saved and switch reloaded.


VRF configuration is lost when the interface is assigned to a VRF and a second VRF with the same AS number as the first one is configured, configuration saved and the switch is reloaded.


VRF need to reconfigured on the interface

The fix will be integrated in the next ios release c3750-advipservicesk9-mz.122-44.SE with ETA November 07.



oguarisco Mon, 10/22/2007 - 23:59

Hi Tom,

neither I do run BGP, i'll wait for the 44 Release and then upgrade the 3750 which give me problem...hoping that all the others are OK :-)



thblake07 Wed, 10/24/2007 - 05:59

Hi Omar,

I had a chat with the TAC Engineer an it was confirmed that this problem doesn't only apply to BGP. So if you are running OSPF, like I am, you are also affected by the Bug. So I'll wait for the 44 Release as well :-)



thblake07 Thu, 12/20/2007 - 02:10

Just a little update from Cisco:

As I mentioned before the release for c3750-advipservicesk9-mz.122-44.SE was scheduled for one week before Christmas. This is a major release with 800+ bugs and feature release.

Apologies for the delay but what have been confirmed is that the issue you are experiencing have been resolved in this bug id CSCsj05589.

The new ETA for the IOS release is Jan 08.




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