User's Manual

Wireless Topologies 16
As the mobile client seamlessly switches from cell to cell, its network connectivity is
preserved. The user can move freely between the Harmony 802.11a Access Points in
the network. When the roaming client leaves the transmission range of one 802.11a
Access Point, the software automatically polls the other 802.11a Access Point(s) in the
same Extended Service Set (ESS) to continue the network connection.
Note: The cells must overlap to ensure that there are no gaps in coverage so that
the roaming client will always have a connection available.
See Figure 3 for an example of a roaming Infrastructure network. In addition, Harmony
802.11a Access Point may be installed on different IP subnets from the AP Controller,
allowing mobile users to roam across routers. For more information on the Harmony
AP Controller and Access Points, refer to the
Harmony Access Point Controller Model
7560 User’s Guide
.
Guidelines for Roaming
• A Harmony 802.11a client can only roam between Harmony 802.11a Access
Points. An 802.11a client cannot communicate with Harmony 802.11b or OpenAir
Access Points.
• All Harmony 802.11a Access Points must have the same SSID.
• All workstations with Harmony 802.11a client adapters installed must use either
an SSID of “any” or the same SSID as the Access Points that they will roam
between.
• If WEP encryption is enabled, then all 802.11a Access Points and clients must use
the same encryption level and WEP Key(s) to communicate.
• The Access Points’ cells must overlap to ensure that there are no gaps in coverage
and to ensure that the roaming client will always have a connection available.
• All Access Points in the same vicinity should use a unique, independent Channel.
• Access Points that use the same Channel should be installed as far away from
each other as possible to reduce potential interference.