Change of IP range in same VLAN - Cisco Catalyst 3750 Stack

Hi,
I need to change the IP range that I'm currently using in my LAN.
The issue here is that I need both IP ranges to coexist at least for a week until all the old IP addresses are cleared.

What are the steps to add the second IP range to my VLAN?

I'm thinking on adding a secondary IP address to the VLAN, and then add some routing between them.

Am I in the right track?
cargexAsked:
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Don JohnstonInstructorCommented:
Yep.

ip address x.x.x.x y.y.y.y secondary

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cargexAuthor Commented:
So, right now I have this

interface Vlan1
 ip address 172.27.187.254 255.255.255.0
!

after I add the secondary IP address I will have this

interface Vlan1
 ip address 172.27.187.254 255.255.255.0
 ip address 10.10.40.1 255.255.255.0 secondary
!

And will both networks coexist in the same VLAN?
Just like that?
Don JohnstonInstructorCommented:
Yes.  Sometimes things are easy... sometimes.
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arnoldCommented:
Presumably, you will change the allocation scope on the vlan on the DHCP side.  If you are using a DHCP server, you would also need to change/update the ip helper configuration to reference the new ip segment to match the scope on the DHCP server to the new segment.
cargexAuthor Commented:
Good morning Don,
I just added the secondary IP, but from a test PC configured with an IP of the new range (10.10.40.30) I can't connect to a device in the other range (172.27.187.1).

I can connect to other vlans, though.

What am I missing here?
Don JohnstonInstructorCommented:
You're not missing anything. It should work the same for the local addresses as the non-local addresses.

From a device on the 10.10.40.0 network, can you successfully ping the 172.27.287.254 address?

From a device on the 172.27.287.0 network, can you successfully ping the 10.10.40.1 address.
cargexAuthor Commented:
No, I can't.

C:\ping 10.10.40.1

Pinging 10.10.40.1 with 32 bytes of data:
Request timed out.
Request timed out.
Request timed out.
Request timed out.

Ping statistics for 10.10.40.1:
    Packets: Sent = 4, Received = 0, Lost = 4 (100% loss),




Ethernet adapter Ethernet:

   Connection-specific DNS Suffix  . :
   Description . . . . . . . . . . . : Qualcomm Atheros AR8162/8166/8168 PCI-E F
ast Ethernet Controller (NDIS 6.30)
   Physical Address. . . . . . . . . : 08-9E-01-D1-E2-51
   DHCP Enabled. . . . . . . . . . . : Yes
   Autoconfiguration Enabled . . . . : Yes
   Link-local IPv6 Address . . . . . : fe80::818e:9b9f:6ce:286d%4(Preferred)
   IPv4 Address. . . . . . . . . . . : 172.27.187.206(Preferred)
   Subnet Mask . . . . . . . . . . . : 255.255.255.0
   Lease Obtained. . . . . . . . . . : Monday, July 27, 2015 9:07:11 AM
   Lease Expires . . . . . . . . . . : Tuesday, July 28, 2015 9:07:11 AM
   Default Gateway . . . . . . . . . : 172.27.187.1
   DHCP Server . . . . . . . . . . . : 172.27.187.2
   DHCPv6 IAID . . . . . . . . . . . : 252222977
   DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-19-83-F7-8C-08-9E-01-D1-E2-51

   DNS Servers . . . . . . . . . . . : 172.27.187.1
                                       75.75.75.75
cargexAuthor Commented:
But from the device in the 10.10.40.0/24
I can ping the Cisco Stack 10.10.40.1
and I can ping ips in other vlans
Don JohnstonInstructorCommented:
There's your problem:

Default Gateway . . . . . . . . . : 172.27.187.1

According to your previous post, the (primary) IP address of the VLAN 1 interface is 172.27.187.254.  

Change the default gateway to 172.27.287.254 and you should be okay.
arnoldCommented:
The addition of secondary IP range to a VLAN only competes that task, your issue is likely related to ACLs that restrict what traffic and to where is permitted to and from each VLAN and to the Internet.

What is on ip 172.27.187.1?

Double check your 172.27.187 scope definition on the DHCP server and look at the options you are setting this is where the default IP and name servers you are pushing.
cargexAuthor Commented:
You are right, I can ping from a PC in 10.10.70.0/24 to another PC in 172.27.187.0/24
But I still can't ping from the same PC (10.10.70.30) to 172.27.187.1

I have a firewall on 172.27.187.1
That's our Internet access.
cargexAuthor Commented:
Don,
I think I have to add a new route to my firewall so that it knows where the 10.10.70.0/24 is.
But it is requesting me to restart and I will need a window for that.

I will leave this question open until I can restart the firewall.

Thanks.
arnoldCommented:
In your comment, your secondary VLAN IP is 172.27.187.254
arnoldCommented:
I think to you are confusing the question. You need to post what IP and the information the 10.10.40.0/24 segment ip is allocated and its settings.
Not sure where the 10.10.70.0/24 segment is coming from.
Don JohnstonInstructorCommented:
If the default gateway is NOT the SVI, then the firewall will need a route to the secondary network.  And you may need to modify ACL's or any other permissions.
cargexAuthor Commented:
I added the route to the 10.10.40.0/24 in the firewall (172.27.187.1) and it started working.

Right now I have both networks
172.27.187.0/24
10.10.40.0/24
working together on the same Vlan1 and I can assign IPs of any of these ranges to any device and it can connect without any issues.
Exactly what I wanted.

Thank you very much guys, your help is greatly appreciated!
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