One amongst the most overlooked configuration in Wireless
LAN is the Wireless Access Point hostnames. Few network administrators leave
the
Hostnames to their factory shippped defaults, while few will
use all the characters that are permissible (for instance 32 characters in
Cisco) to make the name self-illustrative.
Both approaches have their own disadvantages and the rather
recommended limit is of only 15 characters as will be illustrated in preceding
section.
Disadvantages of Leaving the Wireless Access Point Hostnames to their
defaults
By default the Wireless Access Points comes with their
hostnames as their mac address typically appended by character “AP”. This
approach is rather considered a most careless approach since once we see
Wireless Access Point(s) going down on the Wireless LAN Controller / Network
Management Solution, it would be difficult to determine which specific location
of an Access Point has gone down.
On the contrary having a meaningful AP host name which
depicts the location of an Access Point makes it lot more easier to determine
the area of compromise and also the to take an appropriate action. These
actions could include verifying the PoE status on the AP’s switchport, rectify
the patch cord related issues or identify similar issues and accordingly
address them for the specific AP identified through its descriptive Hostname.
Disadvantages of Using the Wireless Access Point Hostnames with its full
permissible limits.
Vendors like Cisco does allow the AP hostnames to be of up
to 32 characters. This has a major drawback during troubleshooting when we are
require to take Over the Air Packet captures and the information element would
be restricted with only 15 characters in length.
The snippets below reflects the configured AP Hostname
characters and those reflected in the IE Element of Wireshark Packet capture.
Configured AP Hostname
Reflected AP Hostname
Recommended Wireless Access Point Hostnames
Its thus recommended to use the Wireless Access Point Hostnames
which are self descriptive and also at the same time well within the character
limit of 15 else any hostname that is beyond 15 character will not get
reflected in the OTA packet captures.
In order to meet this requirement, its recommended to develop a naming convention document for your project/ site wherein shorter length codes are used to signify the campus, building & Floor name or number. Based on your site (indoor/ outdoor) you will have to innovate accordingly so as to have it well within 15 characters. Below table is one such example.
Step 1: Evaluate the image that you wish to put on the WLC
Look for the Cisco suggested image
For the deployments which are not particular about availing
the most recent features, its always a safer approach to look for Cisco suggest
image. This is generally depicted by having a “star” beside the image on CCO
page.
Step 2: Evaluate the WLC code compatibility matrix
The WLAN infrastructure traditionally comprises of Cisco
WLC, Prime, CMX and MSE (wIPS). Thus while planning to upgrade the WLC code, it
quite essential to evaluate the code compatibility matrix as you may be
required to consider upgrading these components as well.
When ever we are trying to upgrade the WLC image to the
latest available code, identifying the upgrade path is quite essential. If the
WLC is running a very older code, then it may be required to proceed with step
upgrade by moving to the intermediate image and then the image of interest.
The current Cisco WLC code available at the time of writing
is 8.8.x and in order to have this code the minimum code, the WLC should be
running is 8.5.x
Step 4: Preliminary tasks before the schedule of code upgrade
a.
Make sure no firewall policies are changed.
Evaluate if there has been any changes to the firewall
policies. When a network is being deployed, people generally prefer allowing
communication between infrastructure devices. Once the network matures, deployments
generally prefer introducing stringent firewall rules allowing communication
between only specific devices and on specific ports.
The unique part is, these firewall policies would not immediately
be seen taking into effect for the already established TCP sessions between the
network devices. The moment we reset these TCP sessions (in our case the reload
of WLC resulting from code upgrade), the existing TCP session would go down and
firewall rules to only allow specific communication kicks in. If the firewall
rules misses to have any communication between the networking equipment then
they would not be able to communicate.
While the WLCs are operating in box to box HA, the code on
them cannot be upgraded separately.
The code has to be
first uploaded on the primary which automatically gets pushed on to the
standby. Once the active WLC is successfully upgraded, the active WLC executes
all the upgrade scripts and transfers the entire image to the Standby WLC using
the Redundant Port.
Standby WLC starts executing the upgrade scripts upon
receiving the entire image on the active WLC.
Verification of WLC image pre-download
On the WLC is uploaded with the desired image of interest,
cross check from the
