Cabletron Systems NB30 Changing Hello Time, Changing Max Age Time, Changing Forwarding Delay Time

NB-30 Bridging

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CAUTION

All bridges in a network must use the same Spanning Tree version. Mixing Spanning Tree Algorithm protocols will cause an unstable network.

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 NB-30 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 NB-30 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)

Bridge Spanning Tree 3-23