Extreme Networks Altitude 3500 Series, Product Reference Manual

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Configuring Mesh Networking
Altitude 3500 Series Access Point Product Reference Guide
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A mesh network must use one of the two access point LANs. If intending to use the access point for
mesh networking support, Extreme Networks recommends configuring at least one WLAN (of the 16
WLANs available) specifically for mesh networking support.
The client bridge creates up to three connections if it can find base bridges for connection. If the
connections are redundant (on the same network), then one connection will be forwarding and the
others blocked. However, if each of the connections links to a different wired network, then none are
redundant and all are forwarding. Thus, the bridge automatically detects and disables redundant
connections, but leaves non-redundant connections forwarding. This gives the user the freedom to
configure their topology in a variety of ways without limitations. This is important when configuring
multiple access points for base bridge support in areas like a shipping yard where a large radio
coverage area is required. For more information on configuring the access point in respect to specific
usage scenarios, see
“Mesh Network Deployment—Quick Setup” on page 534 .
NOTE
Since each access point can establish up to 3 simultaneous wireless connections, some of these
connections could be redundant. If this is the case, the STP algorithm defines which links are the redundant links
and disables those links from forwarding.
If an access point is configured as a base bridge (but not as a client bridge) it operates normally at boot
time. The base bridge supports connections made by other client bridges.
The dual-radio model access point affords users better optimization of the mesh networking feature by
enabling the access point to transmit to other mesh network members using one independent radio and
transmit with associated MUs using the second independent radio. A single-radio access point has its
channel utilization and throughput degraded in a mesh network, as the AP’s single radio must process
both mesh network traffic with other access points and MU traffic with its associated devices.
CAUTION
Only Extreme Networks Altitude 3510 or Altitude 3550 model access points can be used as base bridges,
client bridges or repeaters within an access point supported mesh network. If utilizing a mesh network, Extreme
Networks recommends considering a dual-radio model to optimize channel utilization and throughput.
The Altitude 35xx Client Bridge Association Process
An access point in client bridge mode performs an active scan to quickly create a table of the access
points nearby. The table contains the access points matching the ESS of the client bridge AP’s WLAN.
The table is used to determine the best access point to connect to (based on signal strength, load and the
user's configured preferred connection list).
The association and authentication process is identical to the MU association process. The client access
point sends 802.11 authentication and association frames to the base access point. The base access point
responds as if the client is an actual mobile unit. Depending on the security policy, the two access points
engage in the normal handshake mechanism to establish keys.
After device association, the two access points are connected and the system can establish the bridge
and run the spanning tree algorithm. In the meantime, the access point in client bridge mode continues
to scan in the background attempts to establish an association with other access points using the same
ESS on the same channel.