Motorola WiNG 5.5 Reference Manual page 329

Figure 5-150 Device Overrides - Network - L2TPv3 screen, Add T2TP Tunnel Configuration
10. If creating a new tunnel configuration, assign it a 31 character maximum Name.
11. Define the following Settings required for the L2TP tunnel configuration:
Local IP Address
MTU
Enter the IP address assigned as the local tunnel end point address, not the interface IP
address. This IP is used as the tunnel source IP address. If this parameter is not specified,
the source IP address is chosen automatically based on the tunnel peer IP address. This
parameter is applicable when establishing the tunnel and responding to incoming tunnel
create requests.
Set the maximum transmission unit (MTU). The MTU is the size (in bytes) of the largest
protocol data unit the layer can pass between tunnel peers. Define a MTU from
128 - 1,460 bytes. The default setting is 1,460. A larger MTU means processing fewer
packets for the same amount of data.
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