Extreme Networks Summit WM3000 Series Reference Manual page 285

CAUTION
An Access Point is required to have a DHCP provided IP address before attempting layer 3 adoption, otherwise it
will not work. Additionally, the Access Point must be able to find the IP addresses of the controllers on the
network.
To locate controller IP addresses on the network:
Configure DHCP option 189 to specify each controller IP address.
Configure a DNS Server to resolve an existing name into the IP of the controller. The Access Point has to get
DNS server information as part of its DHCP information.
The controller IP address should be the IP address where APs are adopted. It should not be set to 0.0.0.0.
Key aspects of Layer 3 Mobility include:
Seamless MU roaming between controllers on different Layer 3 subnets, while retaining the same IP
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address.
Static configuration of mobility peer controllers.
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Layer 3 support does not require any changes to the MU. In comparison, other solutions require
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special functionality and software on the MU. This creates numerous inter-working problems with
working with MUs from different legacy devices which do not support Layer 2 switching.
Support for a maximum of 20 peers, each handling up to a maximum of 500 MUs.
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A full mesh of GRE tunnels can be established between mobility peers. Each tunnel is between a pair
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of controllers and can handle data traffic for all MUs (for all VLANs) associated directly or indirectly
with the MU.
Data traffic for roamed MUs is tunneled between controllers by encapsulating the entire Layer 2
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packet inside GRE with a proprietary code-point.
When MUs roam within the same VLAN (Layer 2 Roaming), the behavior is retained by re-homing
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the MU to the new controller so extra hops are avoided while forwarding data traffic.
MUs can be assigned IP addresses statically or dynamically.
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Forward and reverse data paths for traffic originating from and destined to MUs that have roamed
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from one Layer 3 subnet to another are symmetric.
NOTE
When using Layer 3 Mobility ensure that TCP traffic on port 58788 is allowed on the network(s) where mobile units
will be roaming from and to.
To configure Layer 3 Mobility for the controller:
1 Select Services > Layer 3 Mobility from the main menu tree.
The Layer 3 Mobility screen appears with the Configuration tab displayed.
Summit WM3000 Series Controller System Reference Guide
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