Cabletron Systems 9H42X-XX

Bridge Spanning Tree 5-15

Bridging

expires, the port transmits its Conﬁguration BPDU to send conﬁguration

information to the Root. The Hold Time is a ﬁxed value, as speciﬁed by the IEEE

802.1d speciﬁcation.

Port-speciﬁc Parameters

The following ﬁelds are applicable to each bridge port interface present on the

selected 9H42x-xx module:

Priority

If two or more ports on the same bridge are connected to the same LAN segment,

they will receive the same Root ID/Root Cost/Bridge ID information in

Conﬁguration BPDUs received at each port. In this case, the BPDU’s Port ID

information — the transmitting port’s identiﬁer and its manageable Priority

component — is used to determine which is the Designated Port for that segment.

A lower assigned value gives the port a higher Priority when BPDUs are

compared. The allowable range is 0-FF hexadecimal (0-255 decimal); the default is

80 hexadecimal.

Path Cost

Displays the cost that this port will contribute to the calculation of the overall

Root path cost in a Conﬁguration BPDU transmitted by this bridge port. You can

lower a port’s Path Cost to make the port more competitive in the selection of the

Designated Port – for example, you may want to assign a lower path cost to a port

on a higher performance bridge. The allowable range is 1 to 65535.

Designated Cost

Displays the cost of the path to the Root Bridge of the Designated Port on the

LAN to which this port is attached. This cost is added to the Path Cost to test the

value of the Root Path Cost parameter received in Conﬁguration BPDUs.

Designated Root

Displays the unique bridge identiﬁer of the bridge that is assumed to be the Root

Bridge.

Designated Bridge

Displays the network address portion of the Bridge ID (MAC address/priority

component) for the bridge that is believed to be the Designated Bridge for the

LAN associated with this port.

The Designated Bridge ID, along with the Designated Port and Port Identiﬁer

parameters for the port, is used to determine whether this port should be the

Designated Port for the LAN to which it is attached. The Designated Bridge ID is

also used to test the value of the Bridge Identiﬁer parameter in received BPDUs.