Cisco WS-C2960-24TT-L Software Guide - Page 163

Chapter 6 Configuring the System Configuring STP Configuring STP and UplinkFast in a Cascaded Cluster STP uses default values that can be reduced when configuring Catalyst 2900 XL and Catalyst 3500 XL switches in cascaded configurations. If an STP root switch is part of a cluster that is one switch from a cascaded stack, you can customize STP to reconverge more quickly after a switch failure. Figure 6-7 shows modular Catalyst 2900 XL and Catalyst 3500 XL switches in three cascaded clusters that use the GigaStack GBIC. Table 6-3 shows the default STP settings and those that are acceptable for these configurations. Table 6-3 Default and Acceptable STP Parameter Settings (in Seconds) STP Parameter Hello Time Max Age Forwarding delay STP Default (IEEE) 2 20 15 Acceptable for Option 1 1 6 4 Acceptable for Option 2 1 10 7 Acceptable for Option 3 1 6 4 Figure 6-7 Gigabit Ethernet Clusters Catalyst 5000 series switch Catalyst 2900 and 3500 XL switches Cisco 7000 router Catalyst 2900 and 3500 XL switches Catalyst 2900 and 3500 XL switches Catalyst 5000 series/ 6000 backbone Catalyst 6000 switch Layer 3 backbone Cisco 7000 router 33021 Option 1: standalone cascaded cluster Option 2: cascaded cluster connected to a Layer 2 backbone Option 3: cascaded cluster connected to a Layer 3 backbone Enabling UplinkFast on all cluster switches can further reduce the time it takes cluster switches to begin forwarding after a new root switch is selected. 78-6511-08 Catalyst 2900 Series XL and Catalyst 3500 Series XL Software Configuration Guide 6-35