Figure 8. Broken Ethernet Cloud - Enterasys SSIM-H2-02 Installation And User Manual

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This loop can be resolved by making sure that only one translational link is in the
forwarding state or by using the same LAN segment number for all translational
links.
Using two different LAN segment numbers has some interesting advantages. If the
Ethernet cloud becomes physically separated into two parts (see below), both parts
can still communicate via the Token Ring cloud. If the Ethernet cloud is not split
and the root of the spanning tree is on the Token Ring side, there might be a loss of
connectivity between Ethernet stations depending on the CRF numbers configured.
To avoid such hazardous situations, follow the recommendations for the spanning
tree parameter (described below).

Figure 8. Broken Ethernet Cloud

Spanning Tree Configuration
Running the IEEE Spanning Tree Protocol (STP) will create a single spanning tree
covering the entire network. Depending on the topology and configured path costs,
there will be one or more forwarding links between the two clouds.
If there are multiple translational links in multiple switches, the path costs on these
links should be selected so that only one forwards. This will prevent ARE
duplication and the looping problem.
Normally this can be achieved by assigning very large path costs on both sides of
the translational links so that at most one can be forwarding. The SmartStack
SSIM-H2-02 provides support for STP cost manipulation which does not require
cost configuration on both sides of the link.
SSIM-H2-02 Fast Ethernet - Translational Switch SmartStack Interface Module Installation and User Guide Configuration