Tranzeo Wireless Technologies Inc GNVPZ1NT3 Manuale Utente
Chapter 18: Integration with Enterprise Equipment
TR0153 Rev. E1
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18.2 Layer 2 Emulation
Certain back-end systems (e.g. Internet gateways) use the MAC addresses of client devices
for authentication and accounting purposes. The EnRoute500 uses a layer 3 approach to
mesh routing, which means that the client device MAC addresses are typically not provided to
the back-end servers. A layer 2 emulation mode can be enabled on the EnRoute500 to provide
the client device MAC address information to back-end systems. Note that layer 2 emulation
must be enabled to support seamless roaming
When layer 2 emulation is enabled, a mesh neighborhood gateway will send Ethernet (layer 2)
frames to the WAN using the MAC address of the client device the packet originated from as
the source address. Mesh gateways will act as proxies for incoming client traffic, as well as
forward packets with MAC destination addresses of client devices that are in the mesh
neighborhood they service.
In layer 2 emulation mode, a mesh gateway will respond to ARP requests if it has a route to
the target IP address contained in the ARP request. If central DHCP mode is enabled, the
source MAC address will be set to the client device’s MAC address for which a request has
been received, thereby facilitating the emulation of the mesh as a layer 2 network. The list of
subnets for which a mesh gateway has routes includes the mesh and implicit/explicit network
addresses. If central DHCP mode is enabled, the mesh gateway routing table also includes
host routes to addresses in the client address space. Thus care must be taken that these
subnets are not used elsewhere in the network.
In order to reduce the amount of address space consumed by the mesh, the ARP responses
can be limited to a subset of the mesh’s address space. The EnRoute500 can be configured
to:
for authentication and accounting purposes. The EnRoute500 uses a layer 3 approach to
mesh routing, which means that the client device MAC addresses are typically not provided to
the back-end servers. A layer 2 emulation mode can be enabled on the EnRoute500 to provide
the client device MAC address information to back-end systems. Note that layer 2 emulation
must be enabled to support seamless roaming
When layer 2 emulation is enabled, a mesh neighborhood gateway will send Ethernet (layer 2)
frames to the WAN using the MAC address of the client device the packet originated from as
the source address. Mesh gateways will act as proxies for incoming client traffic, as well as
forward packets with MAC destination addresses of client devices that are in the mesh
neighborhood they service.
In layer 2 emulation mode, a mesh gateway will respond to ARP requests if it has a route to
the target IP address contained in the ARP request. If central DHCP mode is enabled, the
source MAC address will be set to the client device’s MAC address for which a request has
been received, thereby facilitating the emulation of the mesh as a layer 2 network. The list of
subnets for which a mesh gateway has routes includes the mesh and implicit/explicit network
addresses. If central DHCP mode is enabled, the mesh gateway routing table also includes
host routes to addresses in the client address space. Thus care must be taken that these
subnets are not used elsewhere in the network.
In order to reduce the amount of address space consumed by the mesh, the ARP responses
can be limited to a subset of the mesh’s address space. The EnRoute500 can be configured
to:
• Disregard ARP requests for mesh IP addresses (typically in the 172.29.0.0/16 subnet)
• Disregard all ARP requests except for IP addresses within the client address space (if
• Disregard all ARP requests except for IP addresses within the client address space (if
centralized DHCP server mode is enabled). Note that this is a superset of the previous
case.
case.
CLI
Layer 2 emulation is enabled with the ‘l2.client_mac_fwd’ parameter in the ‘sys’ interface. This
parameter should be set to the same value for all devices in a given mesh neighborhood. The
example below shows how to enable layer 2 emulation.
parameter should be set to the same value for all devices in a given mesh neighborhood. The
example below shows how to enable layer 2 emulation.
> use sys
sys> set l2.client_mac_fwd=yes
sys> set l2.client_mac_fwd=yes