Mobility or Roaming is the basic requirement, but most of the time Wi-Fi network has this issue that user is facing seamless roaming or connectivity during moving from one Access point to other access during Mobility. They got connection-disconnection, low signal strength and many other issues.
What is Wireless Mobility?
As everybody are using Mobile and it is important part of our life. But along with this mobile some other technologies are required to keep it running like SIM network and Wireless connectivity.
Now you are thinking why I am discussing Mobile here! because we are going to discuss Mobility and how I understand this Mobility in a simple way, that Mobility word comes from Mobile (as I understand). So, in Mobility we will get option or service to connect other AP/ WLC/Network during roaming from one place to another without any disconnection.
Assume. you are in a meeting on your desk and other person also speaking which is causing noise and disturbance. Your laptop connected with LAN cable with LAN port to access office LAN and Internet. What you will do? You cannot go any other desk because once your remove your LAN cable you will be disconnect from Internet and LAN network, then you need to identify the available seat, need your carry your LAN cable, ( if not available at that seat) and it will take time to connect, will take IP address, then you need to join again… but it will take lots of time and it is not possible if you are in meeting with Client or higher Management.
But, if you are connected over Wi-Fi network, then you can simply take your laptop and sit any suitable location without disconnect / Connect or any other issue. This is called Mobility or Roaming.
If a wireless client associates and authenticates to an access point during roaming, the access point’s controller places an entry for that client in its client database. This entry includes:
- The client’s MAC and IP addresses,
- Security context and associations,
- Quality of service (QoS) contexts,
- The WLAN,
- The associated access points
Benefits
Wireless mobility provides several benefits to users, including: –
Increased Productivity: It help to increase productivity, because user can access and share the data, information from anywhere and anytime. He is not bound to any particular location on time.
Enhanced Flexibility: It provide flexibility to work as per user convenience, even user can work from cafeteria as well. He will or can be available from anywhere without any cable or wire connectivity.
Improved Communication: As I mentioned above, if any user faces any issue at some location, user can go some other place to complete like meeting rooms or empty place to attend meeting and all. Also, he can reply or communicate the message over mail or other media immediately from anywhere.
Cost Savings: It helps to save cost like Physical LAN infra setup to provide Lan and Internet access to all user at everywhere. Physical setup has location or area limitation. It cannot be available everywhere, but Wi-Fi can be.
Challenges
Despite the benefits of wireless mobility, it also has some challenges, including:
Network Congestion: in Wireless technology, A Access Point have some user connection limit to provide better connectivity and signal strength, but due to Mobility or roaming other user can connect to a particular access point on which there are already other users are connected and it can network slowness and congestion.
Security: During mobility, security is one the major concern, because use can be connected with un-secured or rough network which cause security breach.
Battery Life: This is not major challenge but still device battery life get effective if a user can roam very frequently, so connect, disconnect, searching new network will affect device battery life.
Interference: When a user roam and searching a new network, it can cause interference as well, because some other devices like Microwaves, cordless phone, Bluetooth devices also work on same frequencies.
Mobility Group
As we discussed above how inter-Controller Layer-2 and Layer-3 Roaming works. In seamless roaming or mobility, it is very important that Mobility design and configuration should well designed and configured.
What is Mobility Group
During designing and configuring Wireless Network, we need to take care whether all services or LAN network will be accessible for all employee or there are some bifurcations. If it is for all or all employee or department can access LAN network from anywhere in organization then all access point and WLC should be part of Single Mobility Group and if organization have multiple Wireless Controller (WLC) and what wants to keep all WLC accessibility separate then we can keep all these WLC in different Mobility Group and user will not have network or data access between Inter-Mobility group WLC.
“A mobility group is configured on a set of controllers by the same mobility group name for seamless roaming for wireless clients between Controllers/AP. Mobility group allows to share information and forward data traffic when inter-controller or inter-subnet roaming occurs. Controllers in the same mobility group can share the context and state of client devices as well as their list of access points so that they do not consider each other’s access points as rogue devices.”
Generally, such kind of requirement and configuration required at large scale wireless deployment where organization have more than 2 WLC.
Let understand, How Mobility Group Works
WLC in Single Mobility Group
In below Diagram. both WLC are in Same Mobility Group, where both WLC have same data and information which helps user for a seamless roaming.
WLC in different Mobility Group
If an organization want to keep wireless network separate due to some security or other reasons, then we can configure WLCs in different Mobility Group and user from other mobility group cannot access data from other WLC.
If any user roaming from Mobility group 1 to Mobility group-2 then user will be disconnected, will get new IP address rom DHCP, associated with new SSID and VLAN the only access the data which are allows on that WLC.
Also, to roam or communicate two different mobility group WLC a L3 devices is required to communicate two different subnet.
FAQ
Q: What is Mobility?
A: When an Wi-Fi user roam or move between multiple Access points and WLC seamlessly and without any interruption, is called Mobility.
Q: What is Mobility Groups?
A mobility group is configured on a set of controllers by the same mobility group name for seamless roaming for wireless clients between Controllers/AP. Mobility group allows to share information and forward data traffic when inter-controller or inter-subnet roaming occurs. Controllers in the same mobility group can share the context and state of client devices as well as their list of access points so that they do not consider each other’s access points as rogue devices.”
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