27
28
Table
4-7 Designated port status
Classification
Designated Bridge
Designated
Port
For
equipment
Equipment connecting directly
with switch and responsible to
transfer BPDU message to
switch
Port used by
designated bridge to
transfer BPDU
message to switch
For LAN
BPDU message to local network
segment equipment
Responsible to transfer
Port used by
designated bridge to
transfer BPDU
message to local
network segment
RSTP
(
Rapid
Spanning
Tree
Protocol
)
is
an
optimized
version
of
STP
.
It
is
"
fast
"
because
the
delay
is
shortened
under
certain
conditions
when
a
port
is
selected
as
the
root
port
and
designated
port
to
enter
to
the
forwarding
state
,
thus
the
time
to
reaching
topology
stability is greatly
reduced.
In RSTP
,
to
ensure
fast
move
of
root port
:
the
old
root
port
of
the
device
has
to stop
forwarding
data
and
the
upstream
designated
port
has to start
forwarding
data
.
In
RSTP
,
to
ensure
fast
move
of
designated
port
:
the
designated
port
should
be
an
edge
port
or
a
port
connected
to
point
to
point
link
.
If
the
designated
port
is
an
edge
port
,
the
designated
port
can
enter
the
forwarding
state;
if
designated
port
is
a
port
connected
to
point
to
point
link
,
the
device
can
handshake with
the
downstream
device
to
give
immediate
response
to
enter
forwarding
state
.
On
[
LACP
/
RSTP
]
page
can
observe
the
current
port
RSTP
information
on
the
switch
,
shown
in
figure
4
-
6
.
Figure 4
-
6
RSTP
Instruction
The meaning of main parameters of the pages as below
.
Table
4
-
8
Parameters description
4.4.2.3 RSTP Introduction
Parameters
Description
Device
priority
As
the
network
bridge
priority
,
network
bridge
and
network
bridge
MAC
address
combined as bridge
ID, of
which minimum
bridge
ID
will
become the root network
.
Sending message
interval
The interval needed to sent
a
BPDU
data
packet.
Maximum
message lifetime
Means the validity of a BPDU data package of a swtich
received from another
switch.
Changing port
status delay
The forward delay of a switch port status in transition
status
(
listening and learning
)
.
Path expenditure
Setting port path cost, only setting when port default path
cost on “off” status Port link cost, with port priority and port
ID form port ID to compare Value range 1
～
200000000
“0”means automatic check
.
Port
priority
The
and
port
ID
form
port
ID
to
compare. Default
port
priority
is
128.
priority of port
in
network
bridge
,
with
port
priority
Point to point port
Switch
port
and
switch
connected
directly
,
then
this port
is
P2P
port
,
RSTP adopts
negotiation
mechanism
for
P2P
port
so as to
achieve
quick transformation of port
status
.
Edge
port
The
network
edge
switch
generally connects with terminal
equipments
,
such
as
PC
,
workstation
.
To
configure
these
terminal
ports
to
Edge
ports can achieve status of
transformation
port without discarding Learning and
forwarding
transformation
course.
RSTP
information Check
RSTP
information
and
port
information