Tranzeo Wireless Technologies Inc GNVPZ1NT3 Manuale Utente
Chapter 13: Client IP Configuration
TR0153 Rev. E1
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13.2 Using a Centralized DHCP Server
Centralized DHCP server mode uses DHCP relaying to enable assignment of IP addresses to
wireless client devices from a common remote DHCP server. The remote DHCP server may
reside either on a host connected to the mesh gateway’s wired segment, or on a server that is
beyond one or more routers. When using a common DHCP server, wireless client devices are
assigned IP addresses from a single address pool, and will roam seamlessly from AP to AP,
assuming sufficiently overlapping AP coverage. In addition, wired clients can also have their IP
addresses assigned by a centralized server.
wireless client devices from a common remote DHCP server. The remote DHCP server may
reside either on a host connected to the mesh gateway’s wired segment, or on a server that is
beyond one or more routers. When using a common DHCP server, wireless client devices are
assigned IP addresses from a single address pool, and will roam seamlessly from AP to AP,
assuming sufficiently overlapping AP coverage. In addition, wired clients can also have their IP
addresses assigned by a centralized server.
DHCP relay as a client IP configuration method is needed to facilitate seamless
roaming within a mesh neighborhood. When enabled together with Layer 2
emulation mode, it facilitates delivery of IP traffic regardless of a client’s point of
attachment to the network. It also puts the mesh network into a mode that makes it
behave like a layer 2 distribution and access network expected by most access
controllers. In this mode, subsequently called “layer 2 mesh emulation mode”,
seamless roaming to and from 3
roaming within a mesh neighborhood. When enabled together with Layer 2
emulation mode, it facilitates delivery of IP traffic regardless of a client’s point of
attachment to the network. It also puts the mesh network into a mode that makes it
behave like a layer 2 distribution and access network expected by most access
controllers. In this mode, subsequently called “layer 2 mesh emulation mode”,
seamless roaming to and from 3
rd
party bridged access points is also supported.
There are three classes of entities that must be configured when using this DHCP mode:
1. The individual EnRoute500s, including the repeaters and the gateway device
2. The central DHCP server
3. Any intermediate router(s) in the path between the DHCP server and the mesh
2. The central DHCP server
3. Any intermediate router(s) in the path between the DHCP server and the mesh
neighborhood gateway device
When using a centralized DHCP server, a Client Address Space (CAS) from which client
device IP addresses are assigned must be defined. The active client access interfaces on the
EnRoute500s (there can be up to 5 per EnRoute500) must also have IP addresses that fall
within the CAS. This is to facilitate DHCP relay and selection of client device IP addresses
from the correct DHCP scope on servers that serve hosts connected to different subnets. The
client access interface IP addresses need to be configured statically and must be contiguous.
It is recommended that a contiguous range of IP addresses at either the beginning or the end
of the CAS be set aside, one for each client access interface on the mesh devices.
The Client Address Space (CAS) is not equivalent to the range of addresses
served by the DHCP server. The DHCP-served address range is a subset of the
CAS. The CAS must also include the addresses for the client access interfaces
and the address of the EnRoute1000’s Ethernet interface when the device is
configured as a gateway.
served by the DHCP server. The DHCP-served address range is a subset of the
CAS. The CAS must also include the addresses for the client access interfaces
and the address of the EnRoute1000’s Ethernet interface when the device is
configured as a gateway.
Consider the example where a mesh neighborhood consists of 3 EnRoute500s, including the
gateway device. The DHCP server resides on a host that also acts as the WAN router and is
connected to the mesh gateway’s wired segment. We will set aside 15 IP addresses for the
mesh devices’ client access interfaces (3 devices, up to 5 interfaces per device). Assuming the