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About Inter-switch trunk (IST)

With SMLT, an inter-switch trunk (IST) connects two aggregation switches. Aggregation switches use the IST to:

• Confirm that they are alive and exchange MAC address forwarding tables.
• Send traffic between single switches attached to the aggregation switches.
• Serve as a backup if one SMLT link fails.

Since the IST is required for the SMLT to operate properly, it represents a single point of failure. As a result, it is recommended that you use multiple links on the IST to ensure reliability and high availability. Nortel Networks recommends using Gigabit Ethernet links for IST connectivity in order to provide enough bandwidth for potential cross traffic.

Note: ATM and POS are not supported for use as IST links.

• About Split Multilink Trunking (SMLT)
• Configuring an IST MLT
• Viewing IST statistics
• Configuring an SMLT