Adaptation For Non-Ip-Compliant Devices - Hirschmann Power MICE User Manual

Static Routing
3.4 Adaptation for non-IP-compli-
ant devices
Some devices use a simplfied IP stack that does not correspond to the
IP standard. Without an ARP request, these devices send their responses to
the MAC address contained as the source address in the requesting packet
(see figure below, no MAC/IP address resolution). These devices exhibit this
behavior with ping requests in particular (ICMP echo request). Some of these
devices also exhibit this behavior with other data packets.
As long as the router interface of the router to which such a device is
connected is itself connected to the MAC address of the physical port, the
router can receive and transmit the packet.
However, if the physical port belongs to a VLAN, the VLAN router interface
then has its own MAC address. Thus the router rejects packets that are being
sent to the port's MAC address.
A terminal device that performs the MAC/IP address resolution according to
the IP standard starts an ARP request to determine the correct MAC address
before sending the reply to the determined VLAN MAC address (see figure
below: MAC/IP standard address resolution using ARP).
VLAN MAC:00:80:63:00:22:00
A
Figure 12: Addressing with simplified IP stack and compliant with the standard
34

3.4 Adaptation for non-IP-compliant devices

Source: 00:80:63:00:00:01
Destination:00:80:63:00:00:01
Source: 00:80:63:00:00:02
Destination:00:80:63:00:22:00
no MAC/IP
address
resolution
MAC/IP address
resolution via ARP
complying with
standard
Routing L3E
Release 4.2 08/08