16-10
Spanning Tree Protocol (STP)
How STP Operates
S
pan
ni
ng Tr
ee P
rot
oc
ol
(ST
P
)
Figure 16-3. Example of Redundant Paths Between Two Nodes
STP Fast Mode
For standard STP operation, when a network connection is established on a
device that is running STP, the port used for the connection goes through a
sequence of states (Listening and Learning) before getting to its final state
(Forwarding or Blocking, as determined by the STP negotiation). This
sequence takes two times the forward delay value configured for the switch.
The default is 15 seconds on HP switches, per the IEEE 802.1D standard
recommendation, resulting in a total STP negotiation time of 30 seconds. Each
switch port goes through this start-up sequence whenever the network con-
nection is established on the port. This includes, for example, when the switch
or connected device is powered up, or the network cable is connected.
A problem can arise from this long STP start-up sequence because some end
nodes are configured to automatically try to access a network server when-
ever the end node detects a network connection. Typical server access
includes to Novell servers, DHCP servers, and X terminal servers. If the server
access is attempted during the time that the switch port is negotiating its STP
state, the server access will fail. To provide support for this end node behavior,
the Switch 4108GL offers a configuration mode, called “Fast Mode”, that
causes the switch port to skip the standard STP start-up sequence and put the
port directly into the “Forwarding” state, thus allowing the server access
request to be forwarded when the end node needs it.
node
A
switch A
node
B
switch D
switch B
switch C
1
path cost:
100
3
path cost: 100
4
path cost:200
• Active path from node A to node B: 1—> 3
• Backup (redundant) path from node A to node B: 4 —> 2 —> 3
2
path cost: 100
Summary of Contents for ProCurve 4108gl Bundle
Page 1: ...hp procurve switch 4108gl management and configuration guide www hp com go hpprocurve ...
Page 2: ......
Page 40: ...2 16 Using the Menu Interface Where To Go From Here Using the Menu Interface ...
Page 154: ...8 24 Time Protocols SNTP Messages in the Event Log Time Protocols ...
Page 350: ...14 44 Port Based Virtual LANs VLANs and GVRP GVRP Port Based Virtual LANs VLANs and GVRP ...
Page 383: ...16 13 Spanning Tree Protocol STP How STP Operates Spanning Tree Protocol STP ...
Page 384: ...16 14 Spanning Tree Protocol STP How STP Operates Spanning Tree Protocol STP ...
Page 442: ...18 30 Troubleshooting Restoring a Flash Image Troubleshooting ...
Page 466: ...B 6 MAC Address Management Determining MAC Addresses MAC Address Management ...
Page 470: ......
Page 481: ...Index 11 Index write memory effect on menu interface 2 13 X Xmodem OS download A 6 ...
Page 482: ......