Local-Area Networks and LAN Switching - CCIE Routing and Switching Exam Certification Guide - page 129

WLAN Security
WLANs without any encryption present a security risk because the SSIDs can be snooped by
using publicly available software. The IEEE 802.11 standard specifies the use of the Wired
Equivalency Privacy (WEP) for encryption. WLANs use two types of WEP keys: 64-bit and
128-bit. Although WEP provides additional security, it has some weaknesses that provide
security risks. By gathering (snooping) traffic, hackers can obtain the WEP keys by using
freeware software.
Some APs can implement MAC address and protocol filtering to enhance security or limit the
protocols over the WLAN. Again, MAC address filtering can be hacked.
To enhance security, WLANs can be implemented with Virtual Private Network (VPN)
software or use the IEEE 802.1x port-based access control protocol. IEEE 802.1x is covered in
the LAN security section in this chapter.
Cisco also provides dynamic per-user, per-session WEP keys to provide additional security over
statically configured WEP keys, which are not unique per user. For centralized user-based
authentication, Cisco developed the Cisco Extensible Authentication Protocol (LEAP), which
uses mutual authentication between the client and the network server and uses IEEE 802.1x for
802.11 authentication messaging. LEAP uses a RADIUS server to manage user information.
New and Future WLAN Standards
The IEEE 802.11a standard provides an increase of throughput from 802.11b with speeds up to
54 Mbps. IEEE 802.11a uses the 5 GHz bands of the UNII frequencies. For this reason, it is not
backward-compatible with 802.11b WLANs.
IEEE 802.11g is an emerging standard that provides faster WLAN speeds in the ISM 2.4 GHz
band. IEEE 802.11g is backward-compatible with 802.11b WLANs.
IEEE 802.11d provides specifications for WLANs in markets not served by the current 802.11,
802.11b, and 802.11a standards.
IEEE 802.11i provides enhancements to the security and authentication protocols for WLANS.
The emerging IEEE 802.15 standard provides specifications for Wireless Personal Area
Networks (WPANs). The emerging IEEE 802.16 standard provides specifications for fixed
Broadband Wireless Access.
Transparent Bridging (TB)
This section covers bridging between Ethernet networks, STP, CRB, and IRB.