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Default VLAN ip address

Default VLAN ip address

I'm sure this is one of those silly questions but I can't seem to find an answer in the doc or anywhere else so here goes.

I have 4 2848's, each with their own IP addys. At the time the switches were installed we had no need for VLANs so none were created besides the DEFAULT. Since then I've had the need to create several VLANS. I did this with PCM, defined the VLANS on one switch and then used Add to VLAN to extend the VLANs to the other switches. When I look in the config for each switch, they've each assigned their IP addy to the DEFAULT VLAN but VLAN 9 has only the one IP I assigned it.

My question is this, can I define the DEFAULT VLAN with only 1 IP addy, like VLAN 9, and then change the configs in the other switches to show 'no ip address' for the DEFAULT VLAN? In essence define the DEFAULT VLAN like VLAN 9 is defined?

Here's the section of the config from two of the switches:

Switch 1
vlan 1
name "DEFAULT_VLAN"
untagged 1-35,Trk1,Trk3-Trk5
ip address 10.1.0.2 255.255.0.0
ip proxy-arp
ip igmp high-priority-forward
exit
vlan 9
name "vlan-9"
untagged 36-38
tagged Trk3-Trk5
ip address 192.168.9.1 255.255.255.0
ip proxy-arp
ip igmp high-priority-forward
exit

Switch 2
vlan 1
name "DEFAULT_VLAN"
untagged 1-35,Trk1,Trk3-Trk5
ip address 10.1.0.3 255.255.0.0
ip proxy-arp
ip igmp high-priority-forward
exit
vlan 9
name "vlan-9"
no ip address
untagged 36-38
tagged Trk3-Trk5
exit





4 REPLIES
Mohieddin Kharnoub
Honored Contributor

Re: Default VLAN ip address

Hi

You can can multiple Vlans on all the Switches, and one Switch has IP Routing Enabled.

On that Switch, assign an IP address for each Vlan.

And on other switches, assign an IP address only for the Management or Default Vlan, that IP is for managing the switch.

So one the Routing Switch, IP for each Vlan, and on other switches, one IP for the default Vlan.

You can also have one IP address per Stack, if you are stacking a group of switches.

Good Luck !!!
Science for Everyone

Re: Default VLAN ip address

So, if I understand you correctly, you're saying that the DEFAULT_VLAN has a different IP address on each switch, the address of the switch itself - 10.1.0.2 and 10.1.0.3 in my configs. I also take it that I can't or shouldn't change this so that the DEFAULT_VLAN has only 1 IP address like the other VLANS do.

I'm assuming then that the DEFAULT_VLAN can't route ip through the switches since the default gateway seems to be undefined or undefinable, unless, of course, I use an external router.
Paulen
Regular Advisor

Re: Default VLAN ip address

Hi,

Telnet your switch on VLAN1. Create IP address on vlan 9. Since you telnet from the same subnet as the vlan1 address, you can safely add a default gateway. Log out and telnet back in on the newly assigned address, either from your default gateway or from anything connected to it, to remove the old address. ("management-vlan" ensures that you are unable to route between this vlan and any other vlans.)

Something like this maybe:

telnet 10.1.0.x
(password)
enable
(password)
conf t
vlan 9
ip add 192.168.9.x 255.255.255.0
exit
ip default-gateway 192.168.9.1
management-vlan 9
logout

telnet 192.168.9.x
(password)
enable
(password)
conf t
vlan 1
no ip address

Re: Default VLAN ip address

So, to summarize my original question and answers:

DEFAULT-VLAN
- takes the ip address of each switch
- has a different ip address on each switch
- cannot route ip without external router

Other VLANS
- ip address defined on one switch
- has a single ip address across all switches
- can route ip using switch engine