Enhancements in Release F.02.11

Fast-Uplink Spanning Tree Protocol (STP)

Enhancements in Release F.02.11

Enhancement

Summary

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Adds the fast-uplink spanning tree (STP) mode to spanning-tree operation

In an 802.1D STP environment with redundant links, an active link failure typically below results in a convergence time of 30 seconds for a backup link to become the active, forwarding link. Fast-uplink STP reduces this time to approximately ten seconds.

Adds the show tech command to the switch troubleshooting capabilities

This command outputs, in a single listing, switch operating and running configura- 162 tion details from several internal switch sources.

Fast-Uplink Spanning Tree Protocol (STP)

Fast-Uplink STP improves the recovery (convergence) time in wiring closet switches with redundant uplinks. Specifically, a Series 2500 switch having redundant links toward the root device can decrease the convergence time (or failover) to a new uplink (STP root) port to as little as ten seconds. To realize this performance, a Series 2500 switch must be:

■Used as a wiring closet switch (also termed an edge switch or a leaf switch).

■Configured for fast-uplink STP mode on two or more ports intended for redundancy in the direction of the root switch, so that at any time only one of the redundant ports is expected to be in the forwarding state.

Note

When properly implemented, fast-uplink STP offers a method for achieving faster failover times than standard STP. While fast-uplink STP remains an effective means for reducing failover time, HP recommends that you move to the Rapid Convergence STP (RSTP; 802.1w) available with software release F.04.08 and greater, for the best failover performance.

Caution

In general, fast-uplink spanning tree on the Series 2500 switches is useful when running STP in a tiered topology that has well-defined edge switches. Also, ensure that an interior switch is used for the root switch and for any logical backup root switches. You can accomplish this by using the Spanning Tree Priority (sometimes termed bridge priority) settings that define the primary STP root switch and at least one failover root switch (in the event that the primary root switch fails). Inappropriate use of Fast-Uplink STP can cause intermittent loops in a network topology. For this reason, the Fast-Uplink STP feature should be used only by experienced network administrators who have a strong understanding of the IEEE 802.1D standard and STP interactions and operation. If you want to learn more about STP operation, you may find it helpful to refer to publications such as:

Perlman, Radia, Interconnections, Second Edition; Bridges, Routers, Switches, and Internetworking Protocols, Addison-Wesley Professional Computing Series, October 1999

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