Configuring MSTP global parameters

PathCostDefaultType

Specifies the version of the spanning tree default path costs to be used by this bridge. A value of 8021d1998 denotes the use of the 16-bit default path costs from IEEE 802.1d-1998. A value of stp8021t2001 denotes the use of the 32-bit default path costs from IEEE 802.1t.

TxHoldCount

Specifies the value used by the port transmit state to limit the maximum transmission rate. The default is 3.

MaxHopCount

Assigns the MSTP bridge maximum hop count. The range is 100 to 4000 one hundredths of a second.

The original MIB erroneously designated the value in hundredths of a second, when it should have been in hops. The replacement MIB kept the range at 100-4000 to remain backwards compatible. To convert this value to hops, divide by 100 so 100-4000 equals 1-40 hops.

NoOfInstancesSupported

Indicates the maximum number of spanning tree instances supported.

MstpUpCount

The number of times the MSTP module is enabled. A trap is generated on the occurrence of this event.

MstpDownCount

The number of times the MSTP module is disabled. A trap is generated on the occurrence of this event.

ForceProtocolVersion

Specifies the version of Spanning Tree Protocol that the bridge currently runs. stpCompatible indicates that the Spanning Tree Protocol as specified in IEEE 802.1d is in use; rstp indicates that the Rapid Spanning Tree Protocol as specified in IEEE 802.1w is in use; and mstp indicates that the multiple spanning tree protocol as specified in IEEE 802.1s is in use.

Although STP and MSTP are variations of the same spanning tree protocol, they communicate information differently. A switch in MSTI mode cannot recognize the spanning tree groups running on a chassis configured with STP. MSTP spanning tree groups are not the same as STP spanning tree groups. Using a switch in MSTP mode with a chassis in STP mode can create a loop in the network.

The default is MSTP.

BrgAddress

Specifies the MAC address used by this bridge if it must be referred to in a unique fashion. This should be the numerically smallest MAC address of all ports that belong to this bridge. If concatenated with MstCistBridgePriority or MstBridgePriority, a unique bridge identifier is formed, which is used in the STP.

Root

Specifies the bridge identifier of the root of the common spanning tree as determined by the STP by this node. This value is used as the CIST root identifier parameter in all configuration bridge PDUs originated by this node.

RegionalRoot

Specifies the bridge identifier of the root of the multiple spanning tree region as determined by the STP as executed of this node. This value is used as the common and internal spanning tree (CIST) regional root identifier parameter in all configuration bridge PDUs originated by this node.

RootCost

Specifies the cost of the path to the CIST root from this bridge.

RegionalRootCost

Specifies the cost of the path to the CIST regional root from this bridge.

RootPort

Specifies the port number of the port which offers the lowest path cost from this bridge to the CIST root bridge.

BridgePriority

Specifies the value of the writable portion of the bridge identifier comprising the first two octets. The values you enter for bridge priority must be in steps of 4096. The default is 32768.

BridgeMaxAge

Specifies the value that all bridges use for MaxAge while this bridge acts as the root. The granularity of this timer is specified as 1 second. An agent can return a bad value error if you attempt to configure a value which is not a whole number of seconds. The default is 2000.

BridgeForwardDelay

Specifies the value that all bridges use for forward delay if this bridge acts as the root. Note that 802.1d specifies that the range for this parameter is related to the value of BridgeMaxAge. The granularity of this timer is specified as 1 second. An agent can return a bad value error if you attempt to configure a value which is not a whole number of seconds. The default is 1500.

HoldTime

Determines the interval length in hundredths of a second during which no more than two configuration bridge PDUs can be transmitted by this node.

MaxAge

Specifies the maximum age of Spanning Tree Protocol information learned from the network on any port before it is discarded. This is the value that this bridge currently uses.

ForwardDelay

Specifies the time value, measured in units of hundredths of a second, that controls how fast a port changes its spanning state after moving towards the forwarding state. This value determines how long the port stays in a particular state before moving to the next state.

TimeSinceTopology Change

Specifies the time (in hundredths of a second) since the TcWhile Timer for any port in this bridge was nonzero for Common Spanning Tree.

TopChanges

Specifies the number of times that there was at least one nonzero TcWhile Timer on this bridge for Common Spanning Tree.

NewRootBridgeCount

Specifies the number of times this bridge detects a root bridge change for Common Spanning Tree. A trap is generated on the occurrence of this event.

RegionName

Specifies the name for the region configuration. By default, the region name is equal to the bridge MAC Address.

RegionVersion

Specifies the version of the MST region.

ConfigIdSel

Specifies the configuration identifier format selector used by the bridge. This has a fixed value of 0 to indicate RegionName. RegionVersions are specified as in the standard.

ConfigDigest

Specifies the configured MD5 digest value for this region, which must be 16 octets long.

RegionConfigChange Count

Specifies the number of times a region configuration identifier change is detected. A trap is generated on the occurrence of this event.