Cabletron Systems CSX400 User Manual
Page 51
The Spanning Tree Protocol Window
3-31
CSX Bridge View
Root Port
The port identiÞer (i.e., the physical index number) for the port that provides the
lowest cost path to the Root Bridge. The Root Port Þeld displays 0 if this bridging
device is the Root Bridge.
Root Cost
Indicates the cost of the data path from this bridge to the Root Bridge. Each port
on each bridge adds a ÒcostÓ to a particular path that a frame must travel. For
example, if each port in a particular path has a Path Cost of 1, the Root Cost
would be a count of the number of bridges along the path. This Þeld will read 0 if
your device is the Root Bridge. See
Changing a PortÕs STA Parameters
,
to Þnd out how to set a portÕs Path Cost.
Hold Time
The minimum time, in seconds, that can elapse between the transmission of
ConÞguration BPDUs. The Hold Time ensures that ConÞguration BPDUs are not
transmitted too frequently through any bridge port. Receipt of a ConÞguration
BPDU starts the Hold Time count at a device. If the Hold Time expires, the port
invokes the Transmit ConÞguration BPDU procedure, which sends conÞguration
change information to the Root. The Hold Time is a Þxed value, as speciÞed by
the IEEE 802.1d speciÞcation.
Root Forward Delay
The Forward Delay (in seconds) that will be implemented by this bridge if it is the
Root or becomes the Root. (The Root Bridge in the network sets the Forward
Delay for all bridges in the Spanning Tree network.)
The IEEE 802.1d speciÞcation recommends that Forward Delay = 15 seconds, with
an allowable range of 4 to 30 seconds.
Root Max Age
The Max Age value (in seconds) that will be implemented if this bridge is the Root
or becomes the Root. (The Root Bridge in the network sets the Max Age for all
bridges in the Spanning Tree network.)
NOTE
The values for the Forward Delay, Max Age, Hold Time, and Hello Time Þelds are stored
within the MIB in units of hundredths of a second rather than seconds; your Cabletron
management application converts hundredths of a second to seconds for display purposes.
You can use any SNMP Set Request tool to edit the values for these three Þelds; just
remember that you must enter your values in hundredths of seconds, rather than in
seconds.
TIP
To ensure proper operation of the Spanning Tree Algorithm, the IEEE 802.1d speciÞcation
recommends that you always observe the following relationship between Forward Delay
and Max Age:
2 x (Forward Delay - 1.0) > Max Age