Cisco 3750 Script vlan issue

swain90 · 22 Oct 2018 at 16:15

Hi All,

I've currently got a script working for a Cisco 3750 switch.

When I restore the script, everything comes across apart from creating the vlans.

In the Show Running config it shows my VLANs as having an IP however they're not in the vlan database.

I've added the vlans manually into the vlan database, saved the config, deleted the vlans and restored the config and they don't go back into the database.

Am I doing something wrong, or is there a config I need to run so that the vlans get stored into the database?

Cheers

Swain90

Eliot · 22 Oct 2018 at 16:59

Hi,

The Vlans are stored in a seperate file on the device outside of the config, believe its called vlan.dat?
So I think that if they aren't there, they can be configured but don't actually exist until someone enters
Conf t
vlan 120
name printers

for example.

Then I believe it is entered into the database, and actually exists.

ChrisD. · 22 Oct 2018 at 18:04

^ correct.

Caged · 22 Oct 2018 at 20:04

Yeah there's an awful lot of legacy stuff on IOS that if you were planning today you would never do

swain90 · 23 Oct 2018 at 09:06

Eliot said:
Hi,

The Vlans are stored in a seperate file on the device outside of the config, believe its called vlan.dat?
So I think that if they aren't there, they can be configured but don't actually exist until someone enters
Conf t
vlan 120
name printers

for example.

Then I believe it is entered into the database, and actually exists.

Thanks for the reply.

The thing I don't understand is that as part of the config, we actually define each vlan by having the below listed at the top of the script;

interface vlan 100
interface vlan 101
interface vlan 102

Annoyingly they don't go in, however all the other parameters which we define which you would need to go into config t for do actually get configured.

Is it just that the vlans that must be entered in manually and not through a config script?

Cheers

Swain90

Eliot · 23 Oct 2018 at 09:26

swain90 said:
Thanks for the reply.

The thing I don't understand is that as part of the config, we actually define each vlan by having the below listed at the top of the script;

interface vlan 100
interface vlan 101
interface vlan 102

Annoyingly they don't go in, however all the other parameters which we define which you would need to go into config t for do actually get configured.

Is it just that the vlans that must be entered in manually and not through a config script?

Cheers

Swain90

You need to do this first:

Conf t
Vlan 100
name Whateveryouwannacallit
Vlan 101
name Whateveryouwannacallit2
Vlan 102
name Whateveryouwannacallit
exit

conf t
interface vlan 100
interface vlan 101
interface vlan 102

Until you have gone into the settings at the start, the vlans don't really exist, are not in vlan.dat, and will not show up in "show vlan" output.
After you have done that command and given them a name, they will do and you will be able to configure them properly

swain90 · 23 Oct 2018 at 11:10

Eliot said:
You need to do this first:

Conf t
Vlan 100
name Whateveryouwannacallit
Vlan 101
name Whateveryouwannacallit2
Vlan 102
name Whateveryouwannacallit
exit

conf t
interface vlan 100
interface vlan 101
interface vlan 102

Until you have gone into the settings at the start, the vlans don't really exist, are not in vlan.dat, and will not show up in "show vlan" output.
After you have done that command and given them a name, they will do and you will be able to configure them properly

Thanks again for your reply. Looks like the normal backup/restore menthod using tftp wouldn't work for the vlan stuff so I've used your examples above and sent a text file with the specific commands in and everything is working fine. Plus using Hyperterminal and the text file is one less thing for someone to set up!

Cheers

matthab · 23 Oct 2018 at 15:08

The vlans will absolutely appear in the running /startup config. You just have to disable VTP in order for this to happen "vtp mode transparent". VTP last time I checked defaults as server which hides them in the VLAN.dat file.

Also you only need "int vlan ***" if you are using layer 3/SVI's. "vlan ***" creates a new layer 2 domain.

Caged · 23 Oct 2018 at 19:48

Put them in a bin and use a Juniper EX-series

Eliot · 25 Oct 2018 at 10:37

swain90 said:
Thanks again for your reply. Looks like the normal backup/restore menthod using tftp wouldn't work for the vlan stuff so I've used your examples above and sent a text file with the specific commands in and everything is working fine. Plus using Hyperterminal and the text file is one less thing for someone to set up!

Cheers

Glad its working