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Redundant Connections to Fast Ethernet Network
A connection to the Ethernet cloud can be made using several translational links from multiple switches. Translational links connected from one switch to the same Ethernet cloud should be grouped into one common CRF with an assigned LAN segment number. From each switch, one CRF can be connected to the same Ethernet cloud.
Redundant connections between source routed and transparent networks may cause ARE frame duplication and infinite ARE frame loops as a result of discarding source routing information during translation from Token Ring to Ethernet format. There are, however, solutions to both problems:
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Infinite frame loops are eliminated by using a common LAN segment number for the entire Ethernet cloud or by proper spanning tree configuration. The recommended CRF number is 4095.
Frame duplication is eliminated by a proper STP configuration allowing only one link between the Token Ring cloud and the Ethernet to be forwarding.
Network Scenarios
Preventing Frame Duplication
The ARE duplication problem can occur only in a configuration with redundant translational links in different switches (see Figure 6).
It is assumed that the network consists of a physically connected Ethernet cloud and a physically connected Token Ring cloud. The two clouds are then connected by a number of links that implement translational bridging.
Figure 6. Frame Duplication
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