Proxy-Arp; Local Routing - ELSA LANCOM Office Manual

R32 Technical basics
The IP router has two separate filter tables, for packets coming from the LAN and from
the WAN. These filter tables can be found in the ELSA LANconfig in the 'TCP/IP'
configuration section on the 'Filtering' tab, or in the
WAN-filter-table

Proxy-ARP

The proxy ARP is a special feature of the IP router. This proxy is used if the transmission
of data to IP addresses takes place in the same logical network as the sender, but the
destination address is still reached via a router. This is the case when individual
workstation computers (teleworkers) are networked via TCP/IP to the company network.
The teleworker then has an IP address which is located in the same local network as all
the other computers in the LAN. A data packet from LAN to the teleworker would usually
only search for a receiver locally, but would not be able to find one.
To take advantage of this function, enable the 'Use Proxy ARP' option (in LANconfig in
the 'TCP/IP' configuration section on the 'Routing' tab or in the
module
The router becomes a proxy for the teleworker with the following entry in the routing
table:
IP address
192.168.110.123
Proxy hosts are not propagated in an RIP packet because the router responds to an ARP
request for the proxy computer with its own MAC address. The distance is set to '0' on
the routing table to indicate this clearly.
The router now responds to the request for the MAC address to the IP address
192.168.110.123 with its own MAC address. This ensures that all packets in the LAN for
the teleworker are now automatically sent to the router, and that data is sent on to the
computer at the other end of the ISDN connection.

Local routing

You know the following behavior of a workstation within a local network: The computer
searches for a router to assist with transmitting a data packet to an IP address which is
not on its own network. This router is usually notified to the operating system by its
property of being the default router or gateway. It is often only possible to enter one
default router which is supposed to be able to reach all the IP addresses which are
unknown to the workstation computer if there are several routers in a network.
ELSA LANCOM Office
or
LAN-filter-table
menu for other configuration modes).
Netmask
255.255.255.255
/Setup/IP-router-table/
menus.
/Setup/IP-router-
Router Dis-
tance
Teleworker01 0
Ver.0:26.08.99/Ver.14:04.04.00
Mask
off