
Using Translation Bridge Services
114060 Rev. A 4-5
• If the destination address is not in the forwarding table, the transparent bridge
forwards the frame out all other TB ports and to the translation bridge. The
translation bridge converts the frame and sends it to the SR network as either
an STE or ARE frame, depending on how you configured the translation
bridge software. (Refer to the next section for details on configuring the
translation bridge software for STE or ARE frames.)
Configuring for STE or ARE Frames
When the translation bridge software forwards a frame with an unknown
destination address onto the SR network, it sends the frame as either an STE or
ARE frame. By default, the translation bridge uses STE frames, so it does not
overload the SR network with excessive ARE traffic. However, when the
translation bridge sends STE frames, all of the traffic between the TB and SR
networks follows the spanning-tree route through the SR network; this may not be
the optimal route.
If you connect TB networks across a large SR network, you may want to configure
the translation bridge to forward frames as ARE frames. This allows the frames to
follow routes other than the spanning-tree route across the SR LAN.
TB to SR Challenges
The translation bridge software must overcome differences in the way that TB and
SR networks implement various aspects of data transmission. These differences
include
• Frame formats
• Frame lengths
• MAC address formats
• LAN speed
The following sections describe how the translation bridge software
accommodates these differences.
Note: An ARE or STE frame includes the ring ID of the TB network in the
route information field.
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