02-01-2008 02:54 AM - edited 03-05-2019 08:52 PM
Hi All
We have a Vlan 10 which has 2 subnets 1.1.1.0/24 and 2.2.2.0/25 which is alive, up and running.
Now we want to divide out the vlans into 2 subnets namely
vlan 10 - 1.1.1.0/24 and
vlan 20 - 2.2.2.0/25
This is on a Cat 3750
What I really wanted to be clear about as I don't want any surprises is
If I have to do
L2
Vlan 20 name ???
L3
Switch A>
Int vlan 20
ip address 2.2.2.10 255.x.x.x
stand ip 2.2.2.100 255.x.x.x
Switch B
Int vlan 20
ip address 2.2.2.11 255.x.x.x
stand ip 2.2.2.100 255.x.x.x
and then do an
interface range fasteth 0/1-10
switch acc vlan 20
which is fine.
At the same time, 2.2.2.10, 2.2.2.11 and 2.2.2.200 are part of the 2.2.2.x/25 subnet which is still in Vlan 10 even though those 3 addresses are available and are not physically in use.
Will this cause a problem? As all I am doing in taking out 3 addresses from a 2.2.2.0/25 although the subnet is currently in vlan 10.
Will this work? Won't it complain that there are duplicate addresses even though the ip addresses are not physically assigned but the subnet is still part of vlan 10.
Thanks
Solved! Go to Solution.
02-01-2008 03:13 AM
Hi
Sorry, got sidetracked, should have answered your previous post.
You are right, you cannot do this as you already have an address out of this subnet allocated to vlan 10.
Not sure you would want to either, because presumkably some of your devices on vlan 10 are using the secondary 2.2.2.x address as their default-gateway so if you used different 2.2.2.x addresses on vlan 20 you would need to update the default-gateways on all your machines using the 2.2.2.x range.
I think you need to accept there will be some downtime and plan accordingly.
HTH
Jon
02-01-2008 03:13 AM
Hi
Sorry, got sidetracked, should have answered your previous post.
You are right, you cannot do this as you already have an address out of this subnet allocated to vlan 10.
Not sure you would want to either, because presumkably some of your devices on vlan 10 are using the secondary 2.2.2.x address as their default-gateway so if you used different 2.2.2.x addresses on vlan 20 you would need to update the default-gateways on all your machines using the 2.2.2.x range.
I think you need to accept there will be some downtime and plan accordingly.
HTH
Jon
02-01-2008 03:17 AM
Thanks Jon. My thoughts exactly.
Thanks
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