7.6.1.0 - Force10 Networks

• Any Layer 2 interfaces that are to be added to the Spanning Tree topology after STP has been enabled
globally must be added manually.
• The IEEE Standard 802.1D allows eight bits for port ID and eight bits for priority. However, the eight
bits for port ID provide port IDs for only 256 ports and the C-Series can contain 336 ports. To
accommodate the increased number of ports, FTOS uses four bits from priority field in the port ID
field.This implementation affects the Bridge MIB (RFC 1493), and you must interpret objects such as
dot1dStpPortDesignatedPort object by using the first four bits as the priority and the last 12 bits as the
port ID.
Table 32 displays the default values for Spanning Tree.
Table 32 STP Default Values
STP Parameter Default Value
Forward Delay 15 seconds
Hello Time 2 seconds
Max Age 20 seconds
Port Cost 100-Mb/s Ethernet interfaces 19
1-Gigabit Ethernet interfaces 4
10-Gigabit Ethernet interfaces 2
Port Channel with 100 Mb/s Ethernet interfaces 18
Port Channel with 1-Gigabit Ethernet interfaces 3
Port Channel with 10-Gigabit Ethernet interfaces 1
Port Priority 8
Configuring Interfaces for Layer 2 Mode
All interfaces on all bridges that will participate in Spanning Tree must be in Layer 2 and enabled.
334 Spanning Tree Protocol