194CHAPTER 8: STP OPERATION

Configuring the Max The scale of an MST region is limited by the max hops in the MST region; which is Hops in an MST Region configured on the region root. As the BPDU travels from the spanning tree root,

each time it is forwarded by a switch, the max hop is reduced by 1. The switch discards the configuration BPDU with 0 hops left. This makes it impossible for the switch beyond the max hops to take part in the spanning tree calculation, thereby limiting the scale of the MST region.

You can use the following command to configure the max hops in an MST region.

Perform the following configuration in system view.

Table 195 Configure the Max Hops in an MST Region

Operation

Command

 

 

Configure the max hops in an MST region.

stp max-hops hop

Restore the default max hops in an MST

undo stp max-hops

region

 

 

 

The more the hops in an MST region, the larger the scale of the region. Only the max hops configured on the region root can limit the scale of MST region. Other switches in the MST region also apply the configurations on the region root, even if they have been configured with max hops.

By default, the max hops of an MST is 20.

Configuring the Any two hosts on the switching network are connected with a specific path Switching Network carried by a series of switches. Among these paths, the one passing more switches

Diameter than all others is the network diameter, expressed as the number of passed switches.

You can use the following command to configure the diameter of the switching network.

Perform the following configuration in system view.

Table 196 Configure the Switching Network Diameter

Operation

Command

 

 

 

Configure the switching network diameter.

stp bridge-diameter bridgenum

Restore the default switching network

undo stp

bridge-diameter

diameter.

 

 

 

 

 

The network diameter is the parameter specifying the network scale. The larger the diameter, the larger the scale.

When a user configures the network diameter on a switch, MSTP automatically calculates and sets the hello time, forward-delay time, and maximum-age time, of the switch, to the desirable values.

The setting of the network diameter takes effect on CIST only, but has no effect on MSTI.

By default, the network diameter is 7 and the three corresponding timers take the default values.

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3Com 10014298 manual Configure the Max Hops in an MST Region, Configure the Switching Network Diameter