Installation guide

Switch Services
5-47
and ARP are tunneled through the home switch. The IP address for the MU is assigned from the VLAN to which
the MU belongs (as determined by the home switch).
The current switch is the switch in the mobility domain an MU is currently associated to. The current switch
changes as the MU roams and establishes different associations. The current switch is responsible for
delivering data packets from the MU to its home switch and vice-versa.
Key aspects of Layer 3 Mobility include:
• Seamless MU roaming between switches on different Layer 3 subnets, while retaining the same IP
address.
• Static configuration of mobility peer switches.
• Layer 3 support does not require any changes to the MU. In comparison, other solutions require
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
• Support for a maximum of 20 peers, each handling up to a maximum of 500 MUs.
• Data traffic for roamed MUs is tunneled between switches by encapsulating the entire L2 packet
inside GRE with a proprietary code-point.
• When MUs roam within the same VLAN (L2 Roaming), the behavior is retained by re-homing the MU
to the new switch so extra hops are avoided while forwarding data traffic.
• MUs can be assigned IP addresses statically or dynamically.
• Forward and reverse data paths for traffic originating from and destined to MUs that have roamed
from one L3 subnet to another are symmetric.
To configure Layer 3 Mobility for the switch:
1. Select Services > Layer 3 Mobility from the main menu tree.
CAUTION An access port is required to have a DHCP provided IP address before
attempting layer 3 adoption, otherwise it will not work. Additionally, the access
port must be able to find the IP addresses of the switches on the network. To
locate switch IP addresses on the network:
• Configure DHCP option 189 to specify each switch IP address.
• Configure a DNS Server to resolve an existing name into the IP of the switch.
The access port has to get DNS server information as part of its DHCP
information. The default DNS name requested by an AP300 is
“Symbol-CAPWAP-Address”. However, since the default name is
configurable, it can be set as a factory default to whatever value is needed.
!