Specifications

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Chapter 13: Topology – Network Services
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Alcatel-Lucent Enterprise Communication Solutions
April 2014 Offer
3.3.5.2.3 Call Admission Control (CAC) and Wi-Fi CAC
The Communication Server performs Call Admission Control (CAC) to manage simultaneous
communications in a multi-site environment, in order to avoid tromboning and bandwidth issues on
the WAN.
CAC is performed by the WLAN switch: CAC parameters are defined per switch/AP group. Wi-Fi___33
CAC parameters are based on the maximum number of calls per AP or on the usable bandwidth per
AP.
In order to avoid bandwidth issues on APs, CAC (Call Admission Control) limits the number of voice
calls using the same AP.
3.3.5.2.4 Security
Several security levels can be implemented to authenticate OmniTouch 8118/8128 WLAN Handsets
(from lowest to highest level):
 Open System: no protection. Everybody can connect to the system. This solution is used for
public hotspot.
 WEP: authentication is based on a key shared by the switch and handsets. Data encryption is
based on the RC4 algorithm (Currently considered as not-secured)
 WPA: authentication is based on a key shared by the switch and handsets. Data encryption is
based on the TKIP algorithm
 WPA2-PSK (also named WPA2-Home): authentication is based on a key shared by the switch
and handsets. Data encryption is based on the AES algorithm.
 WPA2-Enterprise: a radius server (compliant with the IEEE 802.11i standard) is used for
authentication. Two authentications methods can be used:
o EAP-Fast: Mutual authentication is based on a shared secret
o PEAP/MSCHAPv2: Radius Server authentication is based on a certificate
o EAP-TLS: Mutual authentication based on certificates
Since authentication is required for each AP association, roaming between APs generates
voice breaks due to re-authentication duration. The fast handoff feature limits the break time.
After a first authentication with the radius server, re-authentications due to AP roaming are
simplified, data stored in switches and APs are used and the radius server does not need to
be reached.
There are two fast handoff methods:
 OKC (Opportunistic Key Caching): a standard method specified in the 802.11i standard
 CCKM (Cisco Centralized Key Management): a Cisco-proprietary fast AP handoff method, only
supported on Cisco APs
3.3.5.2.5 DSCP tagging
Packets (voice and data) over the WLAN infrastructure carry their own priority in a DSCP tag.
Switches use this tag to process packets with the highest priority level first.
OmniTouch 8118/8128 WLAN Handsets and Communication Servers tag voice packets to the highest
priority.
Typically, the priority level is set to:
 Voice packets: 48 (DSCP value set directly by the OmniTouch 8118/8128 WLAN Handset)
 Video packets: 46
 Best effort packets: 0