3Com 3C13636 Configuration Manual page 261

3Com Router 3000 Ethernet Family
Configuration Guide
Step: Check that the LAN connection between the host and the router is correct.
If the Ethernet is connected to a hub or LAN Switch, check the ON/OFF status of the
LEDs for the link to the hub or LAN Switch. ON LEDs mean that the Ethernet interface
between the host and the router and the network cable are physically normal.
Otherwise, please replace such physical devices as the network adapter, network
cable, router or the relevant interface module.
If the Ethernet is connected using Unshielded Twisted Pair (UTP) and if at least one of
the connection parties supports 100Base-TX, rate matching must be taken into
consideration. An operating rate mismatch between the two parties, i.e., one is working
at 100 Mbps and the other at 10 Mbps, will cause faults. From the perspective of the
one working at 100 Mbps, no connection can be set up. From the perspective of the one
working at 10 Mbps, the connection can be set up but the physical layer activity LED
(ACTIVE) will keep blinking quickly and data transmission and receipt cannot be carried
out properly.
When looking for the connection problems of FE interface on 3Com Series Routers,
there are two prompt messages that are very helpful. These two messages are
displayed on the Console screen upon your operation of selecting speed or connecting
network.
Ethernet 0/0/0: Warning--the link partner do not support 100M mode
Ethernet 0/0/0: Warning--the link partner may not support 10M mode
The first prompt message indicates that the Ethernet interface on the 3Com Series
Router has detected that the remote end does not support 100Mbps operating speed,
but the local end is forced to work at 100Mbps. In this case, you should ensure the
remote end to make the same configuration so that it can work at 100 Mbps. The
second prompt message indicates that the Ethernet interface on the 3Com Series
Router has detected that the remote end does not support 10Mbps operating speed,
but the local end is forced to work at 10 Mbps. In this case, the user should ensure that
the remote end could work at 10 Mbps. However, when the FE interface on 3Com
Series Routers is connected to the 10/100 Mbps adaptive port of the hub, this
information does not mean setting is incorrect.
Step 2: View whether IP addresses of the Ethernet interfaces of the host and router are
in the same subnet. In other words, they must use the same network address but
different host addresses. If they are not in the same subnet, please set a new IP
address.
Step 3: Check that the operating mode of the Ethernet interface is correct. When the
Ethernet is connected using UTP or fiber, 10Base-T/100Base-TX/100Base-FX
standard provisions two operating modes, that is, full duplex and half duplex. When a
hub is used for connecting the Ethernet, the interface should work in half-duplex mode.
When a LAN Switch working in half duplex mode is used, the Ethernet interface of the
router must also work in half duplex mode. If the LAN Switch is working in full duplex
mode, the Ethernet interface of the router must also work in full duplex mode. If the
3Com Corporation
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Chapter 2 LAN Interface Configuration