Untill 7.3 releases, all Wireless LAN controllers (WLC) ran on a dedicated hardware. For example we have 5500 Series, 2100 Series, 2000 series, WiSM on CAT6500 etc. The virtual wireless LAN controller (vWLC) is software that can run on hardware that is compliant with an industry standard virtualization infrastructure. Virtual wireless LAN controllers provide flexibility for users to select the hardware based on their requirement i.e. VMWare,ESx and ESXi 4.x & 5.x version. The Virtual Controllers are NOT expected to replace shipping hardware controllers.
Multiple advantage of using vWLC
1. Flexibility for the customer to select hardware based on their Requirement - So now the end user is not locked into single piece of hardware. We need to use VMware with specific requirements. Also make sure that we get the Hardware support checked from VMware site to run the Virtual controller without any issues. If the virtual controller is installed on a not supported platform, it may not work properly.
2. Reduces Cost, Space requirements and other overhead since multiple boxes can be replaced with a single hardware platform running multiple instances of controllers - This will save clients cost and they can run multiple controllers on this virtual machine. This can also save cost in data center.
3. Independent and mutually exclusive instances allows administrators to use multiple virtual controllers managing different campuses (or even managing multiple customer sites) using the same physical hardware -- The users can run multiple instances on single box. Another advantage is we can run redundancy between two vWLC on the same box.
Enable features provided by the virtualization software which includes High Availability (HA), ease of migration and fail over protection.
VM components relevant for vWLC - vSphere and vCenter Server
1. vSphere – vSphere is a virtualization infrastructure package from VMware., which includes ESX/ESXi hypervisor, vMotion, DRS, HA, Fault Tolerance and vSphere Distributed Switch. vSphere is like a stand alone client. This gives us the ability to create and connect to the virtual machine and make changes to the virtual machine.
2. vCenter Server – The VMware vCenter Server, formerly VMware VirtualCenter, provides a scalable and extensible platform that forms the foundation for virtualization management. vCenter server provides scalable way for the management of the platform. Another concept for vCenter is vMotion.
How it Works?
ESX / ESXi Hypervisor is a software component used in virtualization which allows multiple guest operating systems to run on a host computer all at the same time.
Hypervisors partition physical servers into multiple virtual machines. The hypervisor is going to control the physical disk access to the CPU which allows us to run virtualization. It also allows us to create multiple virtual machines on one machine but we cannot use hypervisor via console.
VMware ESX / ESXi hosts can't be managed directly from the console, and all the management of the base platform will be done via vSphere client or vCenter Server in order to access the console. This is required in case we need to adjust memory or disk size etc.
Virtual Machines are the fundamental building blocks in a virtualized infrastructure. What virtual machine essentially does is, it creates software container and each software container will represent how we are going to create CPU. Every software container contain its own virtual (i.e., software-based) CPU, RAM hard disk and network NIC.
A virtual machine is a tightly isolated software container that can run its own operating systems and applications as if it were a physical computer. Which means on top of this virtual machine, the controller software will be running, in the similar way it does on the physical machine.
In Virtual machine, the vWLC software talks to hypervisor instead of the CPU. Now the hypervisor will check which CPU or disk needs to engaged for the request sent from controller software. A virtual machine behaves exactly like a physical computer and contain its own virtual (i.e., software-based) CPU, RAM hard disk and network interface card (NIC).
so the hypervisor is the interface between the physical box and virtual controller software.
Video Blog on Virtual Wireless Controller (vWLC)
Virtual Controller Support
Hardware: Cisco UCS, UCS Express, HP and IBM servers. We need to make user we are running supported platform and verified from VMware site.
VMware OS: ESX/ESXi 4.x/5.x
FlexConnect Mode: Central and Local Switching. Only FlexConnect Central and Local Switching APs are supported, Local Mode AP will only join the controller but will not associate the clients. So once AP joins the controller we can change the mode from Local mode to Flexconnect mode.
Licensing: Node locked licenses to UDI (eval 60 days)
Max # of APs: 200
Max # of Clients: 3000
Maximum number of sites up to 200
Throughput performance up to 500 Mbps per virtual controller
Management with Cisco Prime Infrastructure 1.2 and above
Features Not Supported on vWLC
Cisco 600 Series OfficeExtend Access Points
Wireless rate limiting (bandwidth contract)
Internal DHCP server
Access points in local mode
Controller High Availability
Outdoor mesh access points (Outdoor AP with FlexConnect mode will work)
Single Virtual Controller Resource Requirement
CPU: 1 virtual CPU
Memory: 2 GB
Disk Space: 8 GB
Network Interfaces: 2 or more virtual Network Interface cards (vNICs)
Network Interfaces: 2 or more virtual Network Interface cards (vNICs). VMware networking consists of virtual network interface cards (vNICs) of various types, the physical NICs on the hosts, and virtual switches to interconnect them.
Each virtual machine has one or more vNICs. These vNICs are connected to a virtual switch to provide network connectivity to the virtual machine.
The guest OS on the VM sees the vNICs as physical NICs. VMware can emulate several popular NIC types, so the guest OS can use standard device drivers for these vNICs.
The physical NICs on an VMware host are called virtual machine NICs (VMNICs), and are used as uplinks to the physical network infrastructure.
Virtual and physical NICs are all tied together by virtual switches.
Suggested Hardware Recommendations for Hosting Cisco Virtual Controllers
UCS R210-2121605W Rack Mount Server (2 RU):
2 * Intel Xeon CPU X5670 @ 2.93 GHz
16 G memory
IBM x3550 M3 Server:
2 * Intel Xeon 5600 series processors with 4 cores each and each core capable of doing hyper threading which gives you 16 CPUs in total @3.6 GHz
SRE 700: Single Core Intel Core Duo 1.86 GHz with 4 GB memory
SRE 900: Dual Core Intel Core Duo 1.86 GHz with 4 GB memory (upgradable to 8 GB)
Rogue AP/Client Support
Number of Rogue APs
Number of Rogue Clients
Cisco Virtual Wireless LAN Controller
Number of RFIDs Supported
Cisco Virtual Wireless LAN Controller
Access Points Requirement
All 802.11n access points with required software version 7.3 are supported
Access points will be operating in FlexConnect mode only.
AP auto convert to FlexConnect is supported on controller.
New access points ordered will ship with 7.3 software from manufacturing unit.
Existing access Points must be upgraded to 7.3 software, before joining a virtual controller.*
The Virtual Controller will support a Console Port virtually which can be used to configure the device initially and manage the controller. Access to the virtual console port is obtained using these methods:
Accessible through vCenter / vSphere client using the vWLC VM’s console tab. Telnet to the port provided by the VMware (done during initial setup).
The Service Port is controlled by the Service-Port Interface and is reserved for out-of-band management of the controller, system recovery and maintenance in the event of a network failure.
Port 1 is used to connect to neighbor switch and will be used for communication with APs connected in the network. Unlike physical controllers, virtual controller supports only a single port. VM will maintain the mapping between physical ports and virtual ports. Any link aggregations are handled at physical ports using NIC teaming.
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