User manual XC-32 XC-320 XC-4200
This rule from the ARP protocol, does not apply if for instance, the B machine wants to
play the part of a proxy-ARP to the C machine. Examine step by step this mechanism on
the following example :
p
The A machine wants to emit an IP frame to the C machine.
p
A’s ARP table has no entry indicating the C‘s MAC address.
p
A sends a request to all the Ethernet network physically present machines.
p
Xcell deceives A, by sending its own MAC addresses to it.
p
A encapsulates C-assigned IP frame in a Xcell-assigned Ethernet frame.
p
Xcell receives the Ethernet frame and extracts the IP frame.
p
As the IP frame is not assigned for it, Xcell consults its routing table in order to
determine the real addressee.
p
Xcell observes that address is accessible via its PPP interface.
p
Xcell encapsulates the C-assigned IP frame in a C-assigned PPP frame.
p
C receives the PPP frame and extracts the IP frame first emitted by A.
If one or several C machines are temporarily network connected, proxy-ARP simplifies the
IP frames routing. Indeed, all machines of the local network see these remote connection
as a local connection.
X.9 - Example n°1 : Remote access server
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