Industrial Managed
Ethernet Switch
User Manual
Configuring
with a Web
Browser
Page
34
of
49
2.6
RSTP
The RSTP or Rapid Spanning Tree Protocol function/feature is the fifth circular icon on the menu bar. It is the icon
with a simple ring network topology. Typicall, the
S
panning
T
ree
P
rotocol (
STP
)
provides a
function to prevent
switching loops and broadcast radiation
at the OSI layer 2. A switching loop
occurs in a network when there are
multiple connections or redundant paths between two network switches or at least two ports are connected on both
sides of the two network switches. The switching loop can create
a broadcast radiation, which is the accumulation
of broadcast and multicast traffics
in a computer network. As broadcast and multicast messages are forwarded by
bridges/switches to every port, the bridges/switches will repeatedly rebroadcast the broadcast messages, and this
accumulation of traffic can flood the network. STP creates a spanning tree topology and disables those links of the
network that are
not part of the spanning tree, which leaves only a single active path between two nodes. This function
can
avoid flooding and increase network efficiency. Therefore, Atop
’
s managed switches deploy spanning tree as a
tool when the users set up connection or port redundancy or fault-tolerance in their network.
RSTP
(
R
apid
S
panning
T
ree
P
rotocol), IEEE 802
.
1W,
is supported
in Atop
’
s EH3408 series lite-managed switches. It is
an evolution of the STP, but it is still backwards compatible with standard STP. RSTP has the advantage over the
STP. When there is a topology change such as link failure in the network, the RSTP will converge significantly faster
to a new spanning tree topology. RSTP improves convergence on point-to-point links by reducing the Max-Age time
to 3 times Hello interval, removing the STP listening state, and exchanging a handshake between two switches to
quickly transition the port to forwarding state.
Figure 2.37 shows the web page of
RSTP
feature which includes
Root Bridge Information
,
Bridge Setting
, and
Port
Information
. The
Root Bridge Information
lists information of the root, which are the
Root Bridge ID
,
Root Priority
,
Root Port
,
Root Path Cost
,
Root Max Age Time
,
Root Hello Time
, and
Root Forward Delay Time
. Next, the
Bridge
Setting
shows current bridge setting which are
Bridge ID
,
Priority
,
Max Age Time
,
Hello Time
, and
Forward Delay
Time
. Finally, the
Port Information
shows current setting and status of each port on the switch. Table 2.10
summarizes the description of parameters of the
Root Bridge Information
.
Figure 2.37 RSTP Feature
