OmniSwitch os6900, Network Configuration Manual, Page: 131 / 942

Configuring Spanning Tree Parameters Configuring STP Bridge Parameters
OmniSwitch AOS Release 7 Network Configuration Guide June 2013 page 6-29
-> spantree hello-time 10
-> spantree cist hello-time 10
Note that the bridge hello time is not configurable for Multiple Spanning Tree Instances (MSTI). These
instances inherit the hello time from the flat mode instance (CIST).
Configuring the Bridge Max-Age Time
The bridge max-age time specifies how long, in seconds, the bridge retains Spanning Tree information it
receives from Configuration BPDU. When a bridge receives a BPDU, it updates its configuration
information and the max age timer is reset. If the max age timer expires before the next BPDU is received,
the bridge attempts to become the root, designated bridge, or change its root port.
The max-age time propagated in a root bridge Configuration BPDU is the value used by all other bridges
in the tree for their own max-age time. Therefore, if this value is changed for the root bridge, all other
VLANs associated with the same instance adopt this value as well.
If the switch is running in the per-VLAN Spanning Tree mode, then a max-age time value is defined for
each VLAN instance. If the switch is running in the flat Spanning Tree mode, then the max-age value is
defined for the flat mode instance. In both cases, the default max-age time is used.
Note. Configuring a low max-age time can cause the Spanning Tree to reconfigure the topology more
often.
To change the bridge max-age time value for a VLAN instance regardless of which mode (per-VLAN or
flat) is active for the switch, use the
spantree max-age command with the vlan parameter. For example,
the following command changes the max-age time for VLAN 455 to 10 seconds:
-> spantree vlan 455 max-age 10
To change the max-age time value for the flat mode CIST instance, use either the spantree max-age
command or the spantree max-age command with the cist parameter. Note that both commands are avail-
able when the switch is running in either mode (per-VLAN or flat). For example, the following commands
change the max-age time value for the flat mode instance to 10:
-> spantree max-age 10
-> spantree cist max-age 10
Note. The max-age time is not configurable for Multiple Spanning Tree Instances (MSTI). These
instances inherit the max-age time from the flat mode instance (CIST).
Configuring the Forward Delay Time for the Switch
The bridge forward delay time specifies how long, in seconds, a port remains in the learning state while it
is transitioning to a forwarding state. In addition, when a topology change occurs, the forward delay time
value is used to age out all dynamically learned addresses in the MAC address forwarding table. For more
information about the MAC address table, see
Chapter 3, “Managing Source Learning.”
The forward delay time propagated in a root bridge Configuration BPDU is the value used by all other
bridges in the tree for their own forward delay time. Therefore, if this value is changed for the root bridge,
all other bridges associated with the same instance adopt this value as well.