Table of
Contents
Chapter 1 MSTP Configuration. 1-1
1.1 MSTP Overview. 1-1
1.1.1 MSTP Protocol Data Unit 1-1
1.1.2 Basic MSTP Terminologies. 1-2
1.1.3 Implementation of MSTP. 1-5
1.1.4 MSTP Implementation on Switches. 1-7
1.2 Root Bridge Configuration. 1-7
1.2.1 Prerequisites. 1-8
1.2.2 MST Region Configuration. 1-8
1.2.3 Root Bridge/Secondary Root Bridge Configuration. 1-10
1.2.4 Bridge Priority Configuration. 1-12
1.2.5 MSTP Operation Mode Configuration. 1-13
1.2.6 MSTP Packet Format Configuration. 1-14
1.2.7 MST Region Maximum Hops Configuration. 1-15
1.2.8 Network Diameter Configuration. 1-15
1.2.9 MSTP Time-related Configuration. 1-16
1.2.10 Timeout Time Factor Configuration. 1-19
1.2.11 Maximum Transmitting Speed Configuration. 1-19
1.2.12 Edge Port Configuration. 1-20
1.2.13 Point-to-point Link-Related Configuration. 1-22
1.2.14 MSTP Configuration. 1-24
1.3 Leaf Node Configuration. 1-25
1.3.1 Prerequisites. 1-26
1.3.2 MST Region Configuration. 1-26
1.3.3 MSTP Operation Mode Configuration. 1-26
1.3.4 Timeout Time Factor Configuration. 1-26
1.3.5 Maximum Transmitting Speed Configuration. 1-26
1.3.6 Edge Port Configuration. 1-26
1.3.7 Path Cost Configuration. 1-26
1.3.8 Port Priority Configuration. 1-29
1.3.9 Point-to-point Link-Related Configuration. 1-30
1.3.10 MSTP Configuration. 1-31
1.4 The mCheck Configuration. 1-31
1.4.1 Prerequisites. 1-31
1.4.2 Configuration Procedure. 1-31
1.4.3 Configuration Example. 1-32
1.5 Protection Function Configuration. 1-32
1.5.1 Introduction. 1-32
1.5.2 Prerequisites. 1-34
1.5.3 BPDU Protection Configuration. 1-34
1.5.4 Root Protection Configuration. 1-35
1.5.5 Loop Prevention Configuration. 1-35
1.5.6 Configuring TC-BPDU Attack Guard. 1-36
1.6 Digest Snooping Configuration. 1-37
1.6.1 Introduction. 1-37
1.6.2 Digest Snooping Configuration. 1-38
1.7 Rapid Transition Configuration.
1-39
1.7.1 Introduction. 1-39
1.7.2 Rapid Transition Configuration. 1-41
1.8 Configuring VLAN-VPN Tunnel 1-42
1.8.1 Introduction. 1-42
1.8.2 Configuring VLAN-VPN tunnel 1-43
1.9 MSTP Displaying and Debugging. 1-44
1.10 MSTP Implementation Example. 1-44
1.11 VLAN-VPN tunnel Configuration Example. 1-47
Chapter 1
MSTP Configuration
1.1
MSTP Overview
Spanning tree protocol (STP)
cannot enable Ethernet ports to transit their states rapidly. It costs two
times of the forward delay for a port to transit to the forwarding state even
if the port is on a point-to-point link or the port is an edge port. This slows
down the spanning tree convergence of STP.
Rapid spanning tree protocol (RSTP) enables the spanning tree to converge rapidly, but it
suffers from the same drawback as that of STP: all
bridges in a LAN share one spanning tree; packets of all VLANs
are forwarded along the same spanning tree, and therefore redundant links
cannot be blocked by VLANs.
As well as the above two protocols,
multiple spanning tree protocol (MSTP) can disbranch
a ring network to form a tree-topological ring-free network to prevent packets
from being duplicated and forwarded endlessly in the ring network. Besides
this, MSTP can also provide multiple redundant paths
for packet forwarding and balances the forwarding loads of different VLANs.
MSTP is compatible with both STP and RSTP. It overcomes the drawback of STP
and RSTP. It not only enables spanning trees to
converge rapidly, but also enables packets of different VLANs
to be forwarded along their respective paths to provide a better load-balancing
mechanism with redundant links.
1.1.1
MSTP Protocol Data Unit
Bridge protocol data unit (BPDU) is the protocol data unit (PDU)
that STP and RSTP use.
The switches in a network transfer BPDUs between each other to determine the topology of the
network. BPDUs carry the information that is needed
for switches to figure out the spanning tree.
BPDUs fall into the following two categories:
l Configuration BPDUs: BPDUs
of this type are used to maintain the spanning tree topology.
l Topology change notification BPDU (TCN BPDN): BPDUs
of this type are used to notify the switches of network changes.
Similar to STP
and RSTP, MSTP uses BPDUs to figure out spanning trees too. In this case, the BPDUs carry MSTP configuration
information of the switches.
1.1.2
Basic MSTP Terminologies
Figure 1-1
illustrates basic MSTP terms (assuming that MSTP is enabled on each switch in this figure).
Figure 1-1 Basic
MSTP terminologies
I. MST region
An MST region (multiple spanning tree region) comprises multiple physically-interconnected MSTP-enabled switches and the corresponding network
segments connected to these switches. These switches have the same region name,
the same VLAN-to-spanning-tree mapping configuration
and the same MSTP revision level.
A switched network can contain multiple MST
regions. You can group multiple switches into one MST region by using the
corresponding MSTP configuration commands. For
example, all switches in region A0 shown in Figure 1-1
have the same MST region configuration: the same region name, the same VLAN-to-spanning-tree mappings (that is, VLAN 1 is mapped to spanning tree instance 1, VLAN 2 is mapped to spanning tree instance 2, and other VLANs are mapped to CIST), the same MSTP
revision level (not shown in Figure 1-1).
II. MSTI
A multiple spanning tree instance (MSTI) refers to a spanning tree in a MST region.
Multiple spanning trees can be established
in one MST region. These spanning trees are independent of each other. For
example, each region in Figure 1-1 contains
multiple spanning trees known as MSTIs (multiple
spanning tree instances). Each of these spanning trees corresponds to a VLAN.
III. VLAN mapping table
A VLAN mapping
table is a property of an MST region. It contains information about how VLANs are mapped to MSTIs. For
example, in Figure 1-1, the information contained
in the VLAN mapping table of region A0 is: VLAN 1 is mapped to MSTI 1; VLAN 2 is mapped to MSTI 2; and
other VLANs are mapped to CIST. In an MST region,
load balancing is achieved by the VLAN mapping table.
IV. IST
An internal spanning tree (IST) is a spanning tree in an MST region.
ISTs together with the common spanning tree (CST) form the common and
internal spanning tree (CIST) of the entire switched network. An IST is a special MSTI; it belongs
to an MST region and is a branch of CIST. In Figure 1-1,
each MST region has an IST, which is a branchof the CIST.
V. CST
A CST is the spanning tree in a switched
network that connects all MST regions in the network. If you regard each MST
region in the network as a switch, then the CST is the spanning tree generated
by STP or RSTP running on
the "switches". In Figure 1-1, the lines
in red depict the CST.
VI. CIST
A CIST is the spanning tree in a switched
network that connects all switches in the network. It comprises the ISTs and the CST. In Figure 1-1,
the ISTs in the MST regions and the CST connecting
the MST regions form the CIST.
VII. Region root
A region root is the root of the IST or an MSTI in a MST region.
Different spanning trees in an MST region may have different topologies and
thus have different region roots. In region D0 shown in Figure
1-1, the region root of MSTI 1 is switch B, and
the region root of MSTI 2 is switch C.
VIII. Common root bridge
The common root bridge is the root of the
CIST. The common root bridge of the network shown in Figure
1-1 is a switch in region A0.
IX. Port roles
In MSTP, the
following port roles exist: root port, designated port, master port, region
edge port, alternate port, and backup port.
l A root port is used
to forward packets to the root.
l A designated port
is used to forward packets to a downstream network segment or switch.
l A master port connects a MST region to the common root. The path
from the master port to the common root is the shortest path between the MST
region and the common root.
l A region edge port
is located on the edge of an MST region and is used to connect the MST region
to another MST region, an STP-enabled region, or an RSTP-enabled region.
l An alternate port
can be a backup port of a master or root port. When it operates as a backup
port of a master port, it becomes the master port if the existing master port
is blocked.
l A loop occurs when
two ports of a switch are connected to each other. In this case, the switch
blocks one of the two ports. The blocked port is a backup port.
In Figure 1-2,
switch A, B, C, and D form an MST region. Port 1 and port 2 on switch A connect
upstream to the common root. Port 5 and port 6 on switch C form a loop. Port 3
and port 4 on switch D connect downstream to other MST regions. This figure
shows the roles these ports play.
l
A port
can play different roles in different MSTIs.
l
The
role a region edge port plays is consistent with the role it plays in the CIST.
For example, port 1 on switch A in Figure 1-2 is a region edge port, and it is a master
port in the CIST. So it is a master port in all MSTIs
in the region.
Figure 1-2 Port
roles
X. Port states
Ports can be in the following three states:
l Forwarding state:
Ports in this state can forward user packets and receive/send BPDU packets.
l Learning state:
Ports in this state can receive/send BPDU packets.
l Discarding state: Ports in this state can only receive BPDU packets.
Table 1-1
lists possible combinations of port states and port roles.
Table 1-1 Combinations
of port states and port roles
1.1.3 Implementation of MSTP
MSTP divides a network into multiple MST regions at Layer 2. The CST is
generated between these MST regions, and multiple spanning trees (or, MSTIs) can be generated in each MST region. As well as RSTP, MSTP uses configuration BPDUs to generate spanning trees. The only difference is
that the configuration BPDUs for MSTP carry the MSTP
configuration information on the switches.
I. Generating the CIST
Through configuration BPDU
comparing, the switch that is of the highest priority in the network is chosen
as the root of the CIST. In each MST region, an IST
is figured out by MSTP. At the same time, MSTP regards each MST region as a switch to figure out the
CST of the network. The CST, together with the ISTs,
forms the CIST of the network.
II. Generating an MSTI
In an MST region, different MSTIs are generated for different VLANs
depending on the VLAN-to-spanning-tree mappings. Each
spanning tree is figured out independently, in the same way as STP/RSTP.
III. Implementation of STP
algorithm
In the beginning, each switch regards
itself as the root, and generates a configuration BPDU
for each port on it as a root, with the root path cost being 0, the ID of the
designated bridge being that of the switch, and the designated port being
itself.
1)
Each switch sends out its configuration BPDUs and operates in the following way when receiving a
configuration BPDU on one of its ports from another
switch:
l If the priority of
the configuration BPDU is lower than that of the
configuration BPDU of the port itself, the switch
discards the BPDU and does not change the
configuration BPDU of the port.
l If the priority of
the configuration BPDU is higher than that of the configuration
BPDU of the port itself, the switch replaces the
configuration BPDU of the port with the received one
and compares it with those of other ports on the switch to obtain the one with
the highest priority.
2)
Configuration BPDUs are compared
as follows:
l The smaller the
root ID of the configuration BPDU is, the higher the
priority of the configuration BPDU is.
l For configuration BPDUs with the same root IDs, the comparison is based on
the path costs. Suppose S is the sum of the root path cost and the
corresponding path cost of the port. The less the S value is, the higher the
priority of the configuration BPDU is.
l For configuration BPDUs with both the same root ID and the same root path
cost, the designated bridge ID, designated port ID, the ID of the receiving
port are compared in turn.
3)
A spanning tree is figured out as follows:
l Selecting the root
bridge
The root bridge is selected by configuration
BPDU comparing. The switch with the smallest root ID
is chosen as the root bridge.
l Selecting the root
port
For each switch (except the one chosen as
the root bridge) in a network, the port that receives the configuration BPDU with the highest priority is chosen as the root port
of the switch.
l Selecting the
designated port
First, the switch generates a designated
port configuration BPDU for each of its port using
the root port configuration BPDU and the root port
path cost, with the root ID being replaced with that of the root port
configuration BPDU, root path cost being replaced
with the sum of the path cost of the root port configuration BPDU and the path cost of the root port, the ID of the
designated bridge being replaced with that of the switch, and the ID of the
designated port being replaced with that of the port.
The switch then compares the resulting
configuration BPDU with the configuration BPDU received from the peer port on another switch. If the
latter takes precedence over the former, the switch blocks the local port and
remains the port's configuration BPDU unchanged, so
that the port can only receive configuration messages and cannot forward
packets. Otherwise, the switch sets the local port to the designated port,
replaces the original configuration BPDU of the port
with the resulting one and releases it regularly.
1.1.4
MSTP Implementation on Switches
MSTP is compatible with both STP and RSTP. That is, switches with MSTP
employed can recognize the protocol packets of STP
and RSTP and use them to generate spanning trees. In
addition to the basic MSTP functions, H3C series
switches also provide the following other functions for the convenience of
users to manage their switches.
l Root bridge hold
l
Root bridge backup
l Root protection
l BPDU protection
l Loop prevention
1.2 Root Bridge Configuration
Table 1-2
lists MSTP-related configurations about root bridges.
Table 1-2 Root
bridge configuration
In a network that
contains switches with both GVRP and MSTP employed, GVRP packets are
forwarded along the CIST. If you want to broadcast packets of a specific VLAN through GVRP, be sure to map
the VLAN to the CIST when configuring the MSTP VLAN mapping table (The CIST
of a network is the spanning tree instance numbered 0.)
1.2.1 Prerequisites
The status of the switches in the spanning
trees are determined. That is, the status (root, branch, or leaf) of each
switch in each spanning tree instance is determined.
1.2.2 MST Region Configuration
I. Configuration procedure
Table 1-3 Configure
an MST region
|
Operation
|
Command
|
Description
|
|
Enter system view
|
system-view
|
—
|
|
Enter MST region view
|
stp region-configuration
|
—
|
|
Configure
a name for the MST region
|
region-name
name
|
Required
The
default MST region name of a switch is its MAC address.
|
|
Configure the VALN
mapping table for the MST region
|
instance instance-id
vlan vlan-list
|
Required
Both commands can be used to configure VLAN mapping tables.
By default, all VLANs
in an MST region are mapped to spanning tree instance 0.
|
|
vlan-mapping modulo modulo
|
|
Configure the MSTP
revision level for the MST region
|
revision-level level
|
Required
The default revision level of an MST
region is level 0.
|
|
Activate the configuration of the MST
region manually
|
active region-configuration
|
Required
|
|
Display the configuration of the current
MST region
|
check region-configuration
|
Optional
|
|
Display the currently valid configuration
of the MST region
|
display stp
region-configuration
|
You can execute this command in any view.
|
Configuring MST region-related parameters (especially the VLAN mapping table) results in spanning trees being
regenerated. To reduce network topology jitter caused by the configuration, MSTP does not regenerate spanning trees immediately after
the configuration; it does this only after you perform one of the following
operations, and then the configuration can really takes effect:
l Activating the new MST region-related settings by using the active
region-configuration command
l Enabling MSTP by using the stp enable command
Switches belong to the same MST region only when they have the same
MST region name, VLAN mapping table, and MSTP revision level.
II. Configuration example
# Configure an MST region, with the name
being “info”, the MSTP revision level
being level 1, VLAN 2 through VLAN
10 being mapped to spanning tree instance 1, and VLAN
20 through VLAN 30 being mapped to spanning tree 2.
<H3C> system-view
[H3C] stp
region-configuration
[H3C-mst-region] region-name info
[H3C-mst-region] instance 1 vlan 2 to 10
[H3C-mst-region] instance 2 vlan 20 to 30
[H3C-mst-region] revision-level 1
[H3C-mst-region] active
region-configuration
# Verify the above configuration.
[H3C-mst-region] check
region-configuration
Admin configuration
Format
selector :0
Region
name :info
Revision
level :1
Instance Vlans Mapped
0 11 to 19, 31 to 4094
1 1 to 10
2 20 to 30
1.2.3 Root Bridge/Secondary Root Bridge Configuration
MSTP can automatically choose a
switch as a root bridge. You can also manually specify the current switch as a
root bridge by using the corresponding commands.
I. Root bridge configuration
Table 1-4 Specify the current switch as
the root bridge of a specified spanning tree
|
Operation
|
Command
|
Description
|
|
Enter
system view
|
system-view
|
—
|
|
Specify the current switch as the root
bridge of a specified spanning tree
|
stp [ instance instance-id ]
root primary [ bridge-diameter bridgenum
] [ hello-time centi-seconds ]
|
Required
|
II. Secondary root bridge configuration
Table 1-5 Specify the current switch as
the secondary root bridge of a specified spanning tree
|
Operation
|
Command
|
Description
|
|
Enter system view
|
system-view
|
—
|
|
Specify the current switch as the
secondary root bridge of a specified spanning tree
|
stp [ instance instance-id ] root secondary [ bridge-diameter
bridgenum ] [ hello-time centi-seconds ]
|
Required
|
Using the stp
root primary/stp root secondary command,
you can specify a switch as the root bridge or the secondary root bridge of the
spanning tree instance identified by the instance-id argument. If the
value of the instance-id argument is set to 0, the stp
root primary/stp root secondary
command specify the current switch as the root bridge or the secondary root
bridge of the CIST.
A switch can play different roles in
different spanning tree instances. That is, it can be the root bridges in a
spanning tree instance and be a secondary root bridge in another spanning tree
instance at the same time. But in one spanning tree instance, a switch cannot
be the root bridge and the secondary root bridge simultaneously.
When the root bridge fails or is turned
off, the secondary root bridge becomes the root bridge if no new root bridge is
configured. If you configure multiple secondary root bridges for a spanning
tree instance, the one with the least MAC address replaces the root bridge when
the latter fails.
You can specify the network diameter and
the Hello time parameters while configuring a root bridge/secondary root
bridge. Refer to section 1.2.8
“Network Diameter Configuration”
and 1.2.9 “MSTP
Time-related Configuration” for information about the network
diameter parameter and the Hello time parameter.
l
You can configure a
switch as the root bridges of multiple spanning tree instances. But you cannot
configure two or more root bridges for one
spanning tree instance. So, do not configure root bridges for the same spanning
tree instance on two or more switches using the stp
root primary command.
l
You can configure multiple secondary root bridges for
one spanning tree instance. That is, you can configure secondary root bridges
for the same spanning tree instance on two or more switches using the stp root secondary command.
l
You can also configure the current switch as the root
bridge by setting the priority of the switch to 0. Note that once a switch is
configured as the root bridge or a secondary root bridge, its priority cannot
be modified.
III. Configuration example
# Configure the current switch as the root
bridge of spanning tree instance 1 and a secondary root bridge of spanning tree
instance 2.
<H3C> system-view
[H3C] stp
instance 1 root primary
[H3C] stp
instance 2 root secondary
1.2.4 Bridge Priority Configuration
Root bridges are selected by the bridge
priorities of switches. You can make a specific switch being selected as a root
bridge by set a higher bridge priority for the switch (Note that a smaller
bridge priority value indicates a higher bridge priority.) A MSTP-enabled switch can have different bridge priorities in
different spanning tree instances.
I. Configuration procedure
Table 1-6 Assign a bridge priority to a
switch
|
Operation
|
Command
|
Description
|
|
Enter system view
|
system-view
|
—
|
|
Set a bridge priority for a switch
|
stp [ instance instance-id
] priority priority
|
Required
The default bridge priority of a switch
is 32,768.
|
Caution:
l
Once you specify a switch as the root bridge or a
secondary root bridge by using the stp root
primary or stp root secondary
command, the bridge priority of the switch is not configurable.
l
During the selection of root bridge, if multiple
switches have the same bridge priority, the one with the least MAC address will
become the root bridge.
II. Configuration example
# Set the bridge priority of the current
switch to 4,096 in spanning tree instance 1.
<H3C> system-view
[H3C] stp instance 1 priority 4096
1.2.5 MSTP Operation Mode
Configuration
A MSTP-enabled switch can operate
in one of the following operation modes:
l STP-compliant
mode: In this mode, the protocol packets sent out of the ports of the switch
are STP packets. If the switched network contains STP-enabled switches, you can configure the current MSTP-enabled switch to operate in this mode by using the stp mode stp
command.
l RSTP-compliant
mode: In this mode, the protocol packets sent out of the ports of the switch
are RSTP packets. If the switched network contains RSTP-enabled switches, you can configure the current MSTP-enabled switch to operate in this mode by using the stp mode rstp
command.
l MSTP mode: In this
mode, the protocol packets sent out of the ports of the switch are MSTP packets, or STP packets if
the ports have STP-enabled switches connected. In
this case, the multiple spanning tree function is enabled as well.
I. Configuration procedure
Table 1-7 Configure MSTP
operation mode
|
Operation
|
Command
|
Description
|
|
Enter system view
|
system-view
|
—
|
|
Configure the MSTP
operation mode for the switch
|
stp mode { stp
| rstp | mstp
}
|
Required
A MSTP-enabled
switch operates in the MSTP mode by default.
|
II. Configuration example
# Configure the current switch to operate in
the STP-compliant mode.
<H3C> system-view
[H3C] stp
mode stp
1.2.6 MSTP Packet Format Configuration
You can set the MSTP
packet format to the following three formats for a port: auto, legacy,
and dot1s (802.1s).
l With the MSTP packet format set to auto,
the port automatically determines the format of the packets to be transmitted
according to that of the received MSTP packets. If
the format of the received packets changes repeatedly, MSTP
will shut down the corresponding port to prevent network storm. A port shut
down in this way can only be enabled again by the network administrator.
l With the MSTP packet format set to legacy,
the port only processes and transmits MSTP packets in
legacy format. If packets in dot1s format are received, the
corresponding ports are set as discarding ports to prevent network storm.
l With the MSTP packet format set to dot1s,
the port only processes and transmits MSTP packets in
dot1s format. If packets in legacy format are received, the
corresponding ports are set as discarding ports to prevent network storm.
l All the ports in an aggregation group use the same MSTP packet format.
I. Configuration Procedure
Table 1-8
Configure MSTP packet format for a port
|
Operation
|
Command
|
Description
|
|
Enter system view
|
system-view
|
—
|
|
Enter Ethernet port view
|
interface interface-type interface-number
|
—
|
|
Configure MSTP
packet format
|
stp compliance { auto | dot1s |
legacy }
|
Required
By default, an MSTP
packet is in legacy format.
|
II. Configuration Example
# Configure the MSTP
packet format as dot1s (802.1s).
<H3C> system-view
[H3C] interface Ethernet1/0/1
[H3C-Ethernet1/0/1] stp compliance dot1s
# Restore the MSTP
packet format to the default.
[H3C-Ethernet1/0/1] undo stp compliance
1.2.7 MST Region Maximum Hops Configuration
The maximum hops values configured on the
region roots in an MST region limit the size of the MST region.
A configuration BPDU
contains a field that maintains the remaining hops of the configuration BPDU. And a switch discards the configuration BPDUs whose remaining hops are 0. After a configuration BPDU reaches a root bridge of a spanning tree in a MST
region, the value of the remaining hops field in the configuration BPDU is decreased by 1 every time the configuration BPDU passes a switch. Such a mechanism disables the
switches that are beyond the maximum hops from participating in spanning tree
generation, and thus limits the size of an MST region.
With such a mechanism, the maximum hops
configured on the switch operating as the root bridge of the IST or an MSTI in a MST region
becomes the network diameter of the spanning tree, which limits the size of the
spanning tree in the current MST region. The switches that are not root bridges
in the MST region adopt the maximum hops settings of their root bridges.
I. Configuration procedure
Table 1-9 Configure the maximum hops for
an MST region
|
Operation
|
Command
|
Description
|
|
Enter system view
|
system-view
|
—
|
|
Configure the maximum hops for the MST
region
|
stp max-hops hops
|
Required
By default, the maximum hops of an MST
region is 20.
|
Note that only the maximum hops settings on
the switches operating as region roots can limit the size of the MST region.
II. Configuration example
# Configure the maximum hops of the MST
region to be 30 (assuming that the current switch operates as the region root).
<H3C> system-view
[H3C] stp
max-hops 30
1.2.8 Network Diameter Configuration
In a switched network, any two switches can
communicate with each other through a path, on which there may be some other
switches. The network diameter of a network is measured by the number of
switches; it equals the number of the switches on the longest path (that is,
the path contains the maximum number of switches).
I. Configuration procedure
Table 1-10 Configure the network
diameter for a network
|
Operation
|
Command
|
Description
|
|
Enter system view
|
system-view
|
—
|
|
Configure the network diameter for a
network
|
stp bridge-diameter bridgenum
|
Required
The default network diameter of a network
is 7.
|
The network diameter parameter indicates the
size of a network. The larger the network diameter is, the larger the network
size is.
After you configure the network diameter of
a switched network, A MSTP-enabled switch adjusts its
Hello time, Forward delay, and Max age settings accordingly.
The network diameter setting only applies
to CIST; it is invalid for MSTIs.
II. Configuration example
# Configure the network diameter of the
switched network to 6.
<H3C> system-view
[H3C] stp
bridge-diameter 6
1.2.9 MSTP Time-related
Configuration
You can configure
three MSTP time-related parameters for a switch: Forward delay, Hello time,
and Max age.
l The Forward delay parameter sets the delay of state transition.
Link problems occurred in a network results
in the spanning trees being regenerated and original spanning tree structures
being changed. As the newly generated configuration BPDUs
cannot be propagated across the entire network immediately when the
