FDDI Applications

6-14 Configuring FDDI Frame Translation Settings

Configuring FDDI Frame Translation Settings
The HSIM-F6 interface must be conÞgured to translate packets from an FDDI
frame format to an Ethernet frame format (and vice versa) when bridging packets
between FDDI and Ethernet networks. The Frame Translation window lets you
set the parameters for frame translation.
To access the FDDI Translation window (Figure 6-8):
1. In the Chassis View window, click on FDDI to display the FDDI menu.
2. Click on Frame Translation.
Figure 6-8. The Frame Translation Window

Information about Ethernet and FDDI Frame Types

There are four frame types which can be transmitted on an IEEE 802.3/Ethernet
network Ð Ethernet II, Ethernet 802.2, Ethernet 802.3 (or Raw Ethernet), and
Ethernet SNAP; there two frame types which can be transmitted on an FDDI
network: FDDI 802.2 and FDDI SNAP. Each of these frame types is described in
more detail in the sections that follow. Bridges connecting IEEE 802.3/Ethernet
LANs to an FDDI ring have to provide frame translation, as there are addressing
and frame format differences between the two network topology types.
For an Ethernet frame format to be forwarded onto an FDDI network, the Length
(IEEE 802/SNAP) or Type (Ethernet II) Þeld must be removed (along with any
frame padding), an FDDI Frame Control Þeld must be added, the bit-order of the
address Þelds must be reversed, and the frameÕs CRC Þeld must be recomputed.