JANET Wireless Technology Advisory Service
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Technology
On this page:
- Points to Consider About Wireless Networking
- Wireless Glossary of Terms
- User Authentication
- Surveying Wireless Networks Technical Guide
- moving to 802.11n (link added 8/12/10)
- WiMAX Technology Briefing
- Wireless Security
- The Alphabet Soup of the 802.11 Family of Standards
- The Overlapping Channel Problem
- The Care and Feeding of SSIDs
- Wireless Health and Safety Issues and Recommendations
- Safe Use of Wireless Networks: Web Redirect and 802.1X
- Wireless 802.11 standards
- Mobile Networking 1G to 4G
- Connecting Wired and Wireless Networks
- Guest and Public Network Access
- Rogue Wireless Suppression
Can I use 802.11n in the 2.4GHz space?
Utilising 802.11n in the 2.4GHz is not really recommended as in order to use it properly you use the 40MHz side-by-side channels and there aren’t any that don’t overlap in the 2.4GHz space. It is better to only use the 40MHz mode in the 5GHz as there are lots of channels available; if you do wish to utilise 2.4GHz 802.11n, keep it to the 20MHz mode. This gives clients slightly better coverage/signal strength (not throughput).
Can 802.11a technology be used outdoors?
Yes, Band B, 5.470-5.725Gz can be used to support a network for mobile devices (licence not required) and Band C, 5.725-5.850GHz can be used for inter-building links provided an inexpensive licence is obtained from Ofcom, 5.8GHz Fixed Wireless Access Licence. Band A, 5.150-5.350GHz must NOT be used outside of buildings.
An excellent short paper on the 5GHz bands and legal usage in the UK can be found on this external link:
Can Cisco 'fat' WAPs be used with multiple broadcast SSIDs and dynamic VLANs?
This question concerns 'thick' access points - which are in fact 'smart'/'autonomous'/'distributed' standalone devices. Whilst a lot of organisations deploying large numbers of access points choose to deploy 'lightweight' 'thin' access points, there are a number that prefer to deploy autonomous 'thin' devices - particularly those in the early stages of WLAN deployment and where the size of the WLAN does not justify the cost of distributed technology. Until recently there was a widely-known issue with Cisco fat APs and multiple BSSIDs and dynamic VLAN allocation. This has now been addressed in the latest release of Cisco IOS 12.3.8-JEA.
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