VLANs are used to segment the network and break up the broadcast domains in order to reduce congestion and isolate network problems as well as providing scalability, performance improvement, security and making network additions, moves, and changes easier and more manageable.
And this is my wireless VLAN background with the controllers:
Host A is a wireless LAN client communicating with the wired device, Host B. At the access point, the access point adds an LWAPP Header to the frame and send it to the controller. After processing the 802.11 MAC Header by WLC, it extracts the payload (the IP packet), encapsulates it into an Ethernet frame, and then forwards the frame onto the appropriate wired network, typically adding an 802.1Q VLAN tag.
According to Cisco's "Fundamentals of Wireless Controllers" video (starting at 2:53), the 5508 controller allows you to use much larger subnets and less wireless VLANs. So with a 5508 controller in a completely wireless infrastructure (no wired hosts),
1. I don't need to break up broadcast domains and have multiple subnets and I'm free to use a giant flat network?
2. If I'm allowed to use large subnets, as far as the broadcast traffics (other than ARP and DHCP which are specially handled by WLC) are concerned, how does the controller handle that? I think I still will need multiple VLANs to control them according to my following WLC broadcast handeling background:
"All traffic including broadcast sent to any destination by wireless client get forwarded to WLC from its connected AP. WLC places the broadcast message on to that VLAN, both wired and wireless clients that are part of that vlan interface will get this broadcast message. Now, the receiving wireless clients on that vlan can be associateded on to any/different APs, APs mapped to different AP groups, even APs using different L3 addresses from one or multiple WLCs, WLC inteligently identifies the mapped VLAN interfaces and its respective APs through AP group and forwards the broadcast(encapsulates) as Multicast packet to those specific AP groups. Once APs receives the Multicast(broadcast), it places it on the respective Radio's BSSID(where WLAN/ssid mapped) of AP to reach the right wireless client. AP Radio's BSSID to SSID/WLAN to interface mapping is pushed to AP by WLC at AP join. Also, Wired PCs will receive the broadcast on its vlan as tagged(if tagged, otherwise untagged) from WLC's interface, so does the other WLCs that spans this vlan interface."
You should still follow your best practice for your subnet size. Remember that wireless is half duplex and only one device can talk at a given time. Also... The AP can be in a different vlan, ap group, etc, but the clients are still on the same vlan. So it means that the clients need to be on the same vlan, but the AP's can be on a different subnet since this doesn't matter.
Transferring Crash file from standby: Login to the Active WLC in HA.
From CLI: (Cisco Controller) >transfer upload datatype crash (Cisco
Controller) >transfer upload filename (Cisco
Controller) >transfer upload mode tftp (Cisco Controller) >transfer
This is the start of a display filter cross reference between Wireshark
and OmniPeek. The 1st installment is a table of advanced filters. More
filters will be added as time allows. It is a living doc, so check back
for changes every so often Please feel f...