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Can 2 networks have the same SSID?

I have myself a Cisco 340 series Aironet Access Point and a PC card. I want to

achieve a seamless roaming scenario between 2 networks.

I would like to know whether networks A and B, each having subnets as and respectively, can have the same SSID? I

want a mobile user to be able to be in all 2 networks, but only receive

information from the one network which it is within range.

Community Member

Re: Can 2 networks have the same SSID?

You can have same SSID on A and B.

But if there is a DHCP server in each network, then the users will have to release and renew the IP config.

Community Member

Re: Can 2 networks have the same SSID?

Thanks for your reply...

But I thought DHCP servers will assign a new IP automatically? If the user has to release the old IP to get a new one, he would have to know when he's at the other network? It wouldn't be seamless already?

By the way, I have checked my mobile device, there isn't an option to release and get a new just has an option button whether to allow a DHCP server to assign an IP or specifiy an IP yourself. Please advice...thank you.

Community Member

Re: Can 2 networks have the same SSID?

We have over 600 Ap allover the campus in diffrent Vlans.

All the AP have same SSID. So a wireless client associates with any AP, but it cannot forward packets if it does not have a IP address from the DHCP from the particular VLAN.

We have instructed users to release/renew IP addr. ( On a hand held you can just pullout thewireless card and reinsert it to get a IP address)

There are other complex way to fix this problem, I am still working on it.

So, if you have a single DHCP server in your network with diff. subnets, your wireless client devices will fine.

Community Member

Re: Can 2 networks have the same SSID?

This depends on the OS on the client devices. Win2K and higher will automatically renew IP address information if a user roams into a new IP subnet. There is a relatively significant delay, however (~5sec. until it attempts a renewal).

If these networks are near each other (i.e. in the same building), you may be better served by building a single VLAN for your wireless network. A single wireless VLAN will offer some significant benefits related to security, mobility and manageability.

If these networks are not near each other, or if users will likely be shutting down their machines while moving from one network to another, the IP addressing will not be an issue.

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