02-20-2012 11:30 PM - edited 03-04-2019 03:22 PM
Hi,
I have this weird scenario whereby my customer wanted 3 VLANs and each VLANs should have the same IP.
PC1 (192.168.1.2/24) in VLAN1.
PC2 (192.168.1.2/24) in VLAN2.
PC3 (192.168.1.2/24) in VLAN3.
Is that even possible?
02-21-2012 01:13 AM
Hi,
Yes is it possible with using private vlan. Look link below.
http://www.cisco.com/en/US/docs/switches/lan/catalyst4500/12.2/31sga/configuration/guide/pvlans.html
hth
Muammer
02-21-2012 01:15 AM
Not possible. Switch will throw you an error about overlapping IP subnets.
Thanks
Vivek
02-21-2012 08:34 PM
Hi all, I just got the full information on the setup that my customer wish to do. Basically this is a railway track. There are a total of 12 train stations here. So each train station will have a L2 switch.
Station 1 Switch 1 VLAN 1
Station 2 Switch 2 VLAN 2
.
.
.
Station 12 Switch 12 VLAN 12
All these above L2 switches will be wired back to the core switch in a different location.
Now the customer is going to deploy camera (192.168.1.2/24) on all the train. So when the train reach every station, the camera can connect back to the camera server to provide the image feed without changing IP address. We can expect there will be more than 1 train (all of them with camera and IP of 192.168.1.2/24) stopping at different stations and want to communicate with the server.
Can we do this with PVLAN? Or can we do some form of NAT?
02-21-2012 08:58 PM
12 vlans --12 stations --12 trains, one stopped in each station, --12 camera one active in each station -all camera same IP
If your VLANs are all routed by the same router this is not possible.
Imagine that the router will have to send one packet back to 192.168.1.2. Which camera is going to receive the packet :-) ?
I am having trouble to figure out how the routing table or the arp table of such router will look like in order to meet the requirements.
You need different IP ranges or some NAT on an intermediate router
I am not familiar with bridging but that might solve the problem too but yu need a L2 protocol for the camera
The idea behind private vlans is that in the end all the private vlans share a comon gateway. This solution (pvlans) is supposed to save IP addresses(you do not waste 2 IP pers subnet every time you subnet an IP range in order to separate customers).
02-22-2012 01:07 AM
Hi,
so there will be an L2 (hub and spokes) connection between all the stations and the central site?
Why don't you simply assign different IP addresses 192.168.1.1 ...192.168.1.12 to particular cameras?
Each camera would just connect to a new switch when arrived to a new station but would keep the same IP address all the time.
And from your network point of view you would just see the camera's MAC address moving from one switch to another.
As I suppose it takes some time to move the train from one station to another, you might even not see "MAC address flapping" error in the switch logs.
HTH,
Milan
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