Bridging
2-40 Spanning Tree
Changing Hello Time
If the bridge is the Root Bridge, or is attempting to become the Root, and you
want to change the length of time the bridge waits between sending conÞguration
BPDUs:
1. Highlight the Hello Time field, and type in a new value.
2. Click on Set.
The IEEE 802.1d speciÞcation recommends that Hello Time = 2 seconds, with an
allowable range of 1 to 10 seconds.
Changing Max Age Time
If the device is the Root Bridge or attempting to become the Root, and you want to
change the maximum time that bridge protocol information will be kept before it
is discarded:
1. Highlight the Max Age field, and type in a new value.
2. Click on Set.
The IEEE 802.1d speciÞcation recommends that Max Age = 20 seconds, with an
allowable range of 6 to 40 seconds.
Changing Forwarding Delay Time
If the device is the Root Bridge or attempting to become the Root, and you want to
change the time period the bridge will spend in the Listening state (e.g. either
listening to BPDU activity on the network while moving from the Blocking to the
Learning state or in the Learning state while the bridge is moving from the
Listening to the Forwarding state):
1. Highlight the Forwarding Delay field, and type in a new value.
2. Click on Set.
The IEEE 802.1d speciÞcation recommends that Forward Delay = 15 seconds, with
an allowable range of 4 to 30 seconds.
NOTE
To ensure proper operation of the Spanning Tree Algorithm, the IEEE 802.1d speciÞcation
recommends that you always observe the following relationship between Forwarding
Delay, Max Age, and Hello Time:
2 x (Forwarding Delay - 1.0) > Max Age > 2 x (Hello Time +1.0)