Cisco NME-16ES-1G User Guide - Page 21

16- and 36-Port Ethernet Switch Module for Cisco 2600 Series, Cisco 3600 Series, and Cisco 3700 Series Feature Overview MAC addresses are allocated sequentially, with the first MAC address in the range assigned to VLAN 1, the second MAC address in the range assigned to VLAN 2, and so forth. For example, if the MAC address range is 00-e0-1e-9b-2e-00 to 00-e0-1e-9b-31-ff, the VLAN 1 bridge ID is 00-e0-1e-9b-2e-00, the VLAN 2 bridge ID is 00-e0-1e-9b-2e-01, the VLAN 3 bridge ID is 00-e0-1e-9b-2e-02, and so forth. Default Spanning Tree Configuration In Table 4 you can view the default Spanning Tree configuration values. Table 4 Spanning Tree Default Configuration Feature Default Value Enable state Spanning tree enabled for all VLANs Bridge priority 32768 Spanning tree port priority (configurable on a per-interface 128 basis; used on interfaces configured as Layer 2 access ports) Spanning tree port cost (configurable on a per-interface basis; Fast Ethernet: 19 used on interfaces configured as Layer 2 access ports) Ethernet: 100 Gigabit Ethernet: 19 when operated in 100-Mb mode, and 4 when operated in 1000-Mb mode Spanning tree VLAN port priority (configurable on a 128 per-VLAN basis; used on interfaces configured as Layer 2 trunk ports) Spanning tree VLAN port cost (configurable on a per-VLAN Fast Ethernet: 10 basis; used on interfaces configured as Layer 2 trunk ports) Ethernet: 10 Hello time 2 seconds Forward delay time 15 seconds Maximum aging time 20 seconds Spanning Tree Port Priority In the event of a loop, spanning tree considers port priority when selecting an interface to put into the forwarding state. You can assign higher priority values to interfaces that you want spanning tree to select first, and lower priority values to interfaces that you want spanning tree to select last. If all interfaces have the same priority value, spanning tree puts the interface with the lowest interface number in the forwarding state and blocks other interfaces. The possible priority range is 0 to 255, configurable in increments of 4 (the default is 128). Cisco IOS software uses the port priority value when the interface is configured as an access port and uses VLAN port priority values when the interface is configured as a trunk port. Spanning Tree Port Cost The spanning tree port path cost default value is derived from the media speed of an interface. In the event of a loop, spanning tree considers port cost when selecting an interface to put into the forwarding state. You can assign lower cost values to interfaces that you want spanning tree to select first and higher Cisco IOS Release 12.2(2)XT, 12.2(8)T, and 12.2(15)ZJ 21