As shown in Figure 1-1, dual-uplink networking is widely
applied currently. Usually, spanning tree protocol (STP) is used to implement
link redundancy backup in the network. However, STP is not suitable for users
with a high demand for convergence time. Smart Link can achieve active/standby
link redundancy backup and fast convergence to meet the user demand.
Smart Link has the following features:
l
Active/standby backup for dual-uplink networking
l
Simple configuration and operation
I. Smart Link group
A Smart Link group consists of two member
ports, one master port and one slave port. Normally, only one port (master or
slave) is active, and the other port is blocked, that is, in the standby state.
When link failure occurs on the port in active state, the Smart Link group will
block the port automatically and turn standby state to active state on the
blocked port.
Figure 1-1 Network diagram of Smart Link
In Figure 1-1, Ethernet1/0/1 and Ethernet1/0/2
on Switch A are two member ports of a Smart Link group.
II. Master port
The master port can be either an Ethernet
port or a manually-configured or static LACP aggregation group. For example, you
can configure Ethernet1/0/1 of switch A in Figure 1-1 as the master port through the
command line.
III. Slave port
The slave port can be either an Ethernet
port or a manually-configured or static LACP aggregation group. For example, you
can configure Ethernet1/0/2 of switch A in Figure 1-1 as the slave port through the
command line.
IV. Flush message
When a forwarding link fails, the device
will switch the traffic to the blocked standby link. The former forwarding
entries of each device in the network are no longer suitable for the new
topology, so MAC address forwarding entries and ARP entries must be updated
throughout the network. In this case, the Smart Link group sends flush messages
to notify other devices to refresh MAC address forwarding entries and ARP
entries.
V. Control VLAN for sending flush messages
This control VLAN sends flush messages.
When link switching occurs, the device (Switch A in Figure 1-1) broadcasts flush messages in
this control VLAN.
VI. Control VLAN for receiving
flush messages
This control VLAN is used for receiving and
processing flush messages. When link switching occurs, the devices (Switch B
and Switch C in Figure 1-1)
receive and process flush messages of this control VLAN, and then refresh MAC
forwarding table entries and ARP entries.
l
Currently, the member ports of a Smart Link group
cannot be dynamic link aggregation groups.
l
If the master port or slave port of a Smart Link
group is a link aggregation group, you cannot remove this link aggregation
group directly or change the aggregation group into a dynamic aggregation
group. Before removing this aggregation group, you must unbind the link aggregation
group from the Smart Link.
Figure 1-2 Network diagram of Smart Link operating mechanism
As shown in Figure 1-2, Ethernet1/0/1 on Switch A is active
and Ethernet1/0/2 on Switch A is blocked. When the link connected to Ethernet1/0/1
fails, Ethernet1/0/1 is blocked automatically, and the state of Ethernet1/0/2
turns to active state.
l
When link switching occurs in the Smart Link
group, MAC forwarding entries and ARP entries of each device in the network may
be out of date. In order to guarantee correct packet transmission, you must
enable the Smart Link device to send flush messages to notify the other devices
in the network to refresh their own MAC forwarding entries and ARP entries. In
this case, all the uplink devices must be capable of identifying flush messages
from the Smart Link group and refreshing MAC forwarding entries and ARP
entries.
l
On a Smart Link–enabled device, if a port
is blocked due to link failure, the port remains blocked after the link recovers
from the failure, and does not preempt the traffic resource. Therefore, the
traffic stays stable. The port does not come into the forwarding state until
the next link switching.
Before configuring
a member port of a Smart Link group, you must:
l
Disable the port to avoid loops, thus preventing
broadcast storm.
l
Disable STP on the port.
After completing the configuration, you need to enable the Ethernet
ports disabled before configuring the Smart Link group.
Table 1-1
Smart Link configuration tasks
|
Task
|
Remarks
|
|
Configuring a Smart Link Device
|
Create a Smart Link group
|
Required
|
|
Add member ports to the Smart Link group
|
|
Enable the function of sending flush
messages in the specified control VLAN
|
|
Configuring Associated Devices
|
Enable the function of processing flush
messages received from the specified control VLAN
|
Required
|
A Smart Link device refers to a device on
which Smart Link is enabled and a Smart Link group is configured, and that
sends flush messages from the specified control VLAN. A member port of a Smart
Link group can be either an Ethernet port or a manually-configured or static
LACP aggregation group. You can configure a port or a link aggregation group as
a member of a Smart Link group.
Table 1-2
Configure Smart Link (with ports as the members of the
Smart Link group)
|
Operation
|
Command
|
Remarks
|
|
Enter system view
|
system-view
|
—
|
|
Create a Smart Link group and enter Smart
Link group view
|
smart-link
group group-id
|
Required
|
|
Enable the function of sending flush
messages in the specified control VLAN
|
flush
enable control-vlan vlan-id
|
Required
By
default, no control VLAN for sending flush messages is specified.
|
|
Configure a port as a Smart Link group
member
|
Smart Link
group view
|
port interface-type interface-number { master
| slave }
|
Required
Use either
approach
|
|
Ethernet
port view
|
quit
|
|
interface interface-type interface-number
|
|
port
smart-link group group-id { master | slave }
|
Table 1-3
Configure Smart Link (with link aggregation groups are
the members of the Smart Link group)
|
Operation
|
Command
|
Remarks
|
|
Enter system view
|
system-view
|
—
|
|
Create a Smart Link group and enter Smart
Link group view
|
smart-link group group-id
|
Required
|
|
Configure a link aggregation group as a
member of the Smart Link group
|
link-aggregation group group-id { master | slave }
|
Optional
|
|
Enable the function of sending flush
messages in the specified control VLAN
|
flush enable control-vlan vlan-id
|
Optional
By default, no control VLAN for sending
flush messages is specified.
|
An associated device mentioned in this
document refers to a device that supports Smart Link and locally configured to process
flush messages received from the specified control VLAN so as to work with the
corresponding Smart Link device. As shown in Figure 1-2, all the devices including
Switch C, Switch D, and Switch E on the active and backup links connecting the
Smart Link device (Switch A) and the target uplink device (Switch E) are all
associated devices.
However, you do not have to enable all the
ports of an associated device to process flush messages received from the
specified control VLAN. You need to enable this function only on the ports that
are on the active and backup links connecting the Smart Link device and the target
device. As shown in Figure
1-2, you need to enable this function on Ethernet 1/0/2 and
Ethernet 1/0/3 of Switch C, Ethernet 1/0/2 and Ethernet 1/0/3 of Switch D, and
Ethernet 11/0/1 and Ethernet 1/0/12 of Switch E.
Table 1-4
Enable the specified port to process flush messages
received from the specified control VLAN
|
Operation
|
Command
|
Remarks
|
|
Enter system view
|
system-view
|
—
|
|
Enable the specified port(s) to process
flush messages received from the control VLAN
|
System
view
|
smart-link
flush enable control-vlan vlan-id port interface-type
interface-number [
to interface-type interface-number ]
|
Required,
use either approach.
By
default, no control VLAN for receiving flush messages is specified.
|
|
Ethernet
port view
|
interface interface-type interface-number
|
|
smart-link
flush enable control-vlan vlan-id
|
When configuring Smart Link, pay attention to
the following points:
1)
A port or a link aggregation group cannot serve
as a member port for two Smart Link groups. On the other hand, a port or a link
aggregation group cannot serve as a member for a Smart Link group and a Monitor
Link group at the same time.
2)
STP cannot be enabled on the member ports of a Smart
Link group. An STP-enabled port or a link aggregation group with an STP-enabled
port cannot serve as a member port for a Smart Link group.
3)
A Smart Link/Monitor Link group with members
cannot be deleted.
4)
Smart Link/Monitor Link is mutually exclusive
with remote port mirroring.
5)
When a Combo port operates as a member port of a
Smart Link group, the optical port and the electrical port of the Combo port must
not be both engaged with a cable at the same time.
6)
When you copy a port, the Smart Link/Monitor
Link group member information configured on the port will not be copied to
other ports.
7)
If a single port is specified as a member of a Smart
Link/Monitor Link group, you cannot execute the lacp enable command on
this port or add this port into other dynamic link aggregation groups, because
these operations will make this port become a link aggregation group member.
8)
If no control VLAN is configured for flush
message processing, the device will forward received flush messages without
processing them.
9)
If the control VLAN for receiving flush messages
configured on an associated device is different than the one for sending flush
messages configured on the corresponding Smart Link device, the device will forward
received flush messages without processing them.
10)
In the static or manual link aggregation group which
serves as a Smart Link group member, if a member port can process flush
messages, this function cannot be synchronized to the other ports in the aggregation
group automatically, that is, the other member ports in the aggregation group
cannot process flush messages. The function of processing flush messages must
be manually configured for each port in the aggregation group.
11)
The VLAN configured as a control VLAN to send
and receive flush messages must exist. You cannot directly remove the control
VLAN. When a dynamic VLAN is configured as the control VLAN for the Smart Link
group, this VLAN will become a static VLAN, and the prompt information is displayed.
After the above-mentioned configuration,
you can use the following display commands in any view to view the Smart
Link group information and the statistics information of flush messages
received and processed by current device, so as to verify the configuration.
Use the reset command in user view
to clear flush message statistics.
Table 1-5
Display and debug Smart Link
|
Operation
|
Command
|
Remarks
|
|
Display the information of a Smart Link
group
|
display smart-link group { group-id | all }
|
You can execute the display
command in any view.
|
|
Display the statistics information of
flush messages received and processed by the current device
|
display smart-link flush
|
|
Clear flush message statistics
|
reset smart-link packets counter
|
You can execute the reset command
in user view.
|
I. Network requirements
As shown in Figure 1-3, Switch A is an H3C S3100
series Ethernet switch. Switch C, Switch D and Switch E support Smart Link.
Configure Smart Link feature to provide remote PCs with reliable access to the
server.
II. Network diagram
Figure 1-3
Network diagram for Smart Link configuration
III. Configuration procedure
1)
Configure a Smart Link group on Switch A and
configure member ports for it. Enable the function of sending flush messages in
Control VLAN 1.
# Enter system view.
<switchA> system-view
# Enter Ethernet port view. Disable STP on
Ethernet1/0/1 and Ethernet1/0/2.
[SwitchA] interface Ethernet 1/0/1
[SwitchA-Ethernet1/0/1] stp disable
[SwitchA-Ethernet1/0/1] quit
[SwitchA] interface Ethernet 1/0/2
[SwitchA-Ethernet1/0/2] stp disable
# Return to system view.
[SwitchA-Ethernet1/0/2] quit
# Create Smart Link group 1 and enter the
corresponding Smart Link group view.
[SwitchA] smart-link group 1
# Configure Ethernet1/0/1 as the master
port and Ethernet1/0/2 as the slave port for Smart Link group 1.
[SwitchA-smlk-group1] port Ethernet
1/0/1 master
[SwitchA-smlk-group1] port Ethernet
1/0/2 slave
# Configure to send flush messages within
VLAN 1.
[SwitchA-smlk-group1] flush enable
control-vlan 1
2)
Enable the function of processing flush messages
received from VLAN 1 on Switch C.
# Enter system view.
<SwitchC> system-view
# Enable the function of processing flush
messages received from VLAN 1 on Ethernet 1/0/2.
<SwitchC> smart-link flush
enable control-vlan 1 port Ethernet 1/0/2
3)
Enable the function of processing flush messages
received from VLAN 1 on Switch D.
# Enter system view.
<SwitchD> system-view
# Enable the function of processing flush
messages received from VLAN 1 on Ethernet 1/0/2.
[SwitchD] smart-link flush enable
control-vlan 1 port Ethernet 1/0/2
4)
Enable the function of processing flush messages
received from VLAN 1 on Switch E.
# Enter system view.
<SwitchE> system-view
# Enable the function of processing flush
messages received from VLAN 1 on Ethernet 1/0/2 and Ethernet 1/0/3.
[SwitchE] smart-link flush enable
control-vlan 1 port Ethernet 1/0/2 to Ethernet 1/0/3
Monitor Link is a collaboration scheme
introduced to complement for Smart Link. It is used to monitor uplink and to
perfect the backup function of Smart Link.
A monitor Link consists of an uplink port
and one or multiple downlink ports. When the link for the uplink port of a
Monitor Link group fails, all the downlink ports in the Monitor Link group are forced
down. When the link for the uplink port recovers, all the downlink ports in the
group are re-enabled.
Figure 2-1 Network diagram for a Monitor Link group
implementation
As shown in Figure 2-1,
the Monitor Link group configured on the device Switch A consists of an uplink
port (Ethernet1/0/1) and two downlink ports (Ethernet1/0/2 and Ethernet1/0/3).
A member port can be an Ethernet port, static LACP aggregation group, manual
link aggregation group, or Smart Link group. A Smart Link group can serve as
the uplink port only.
Figure 2-2 Network diagram for a Monitor Link group implementation
As shown in Figure 2-2, the devices Switch C and Switch
D are connected to the uplink device Switch E. Switch C is configured with a
Monitor Link group, where Ethernet1/0/1 is the uplink port, while Ethernet1/0/2
and Ethernet1/0/3 are the downlink ports. Switch A is configured with a Smart
Link group, where Ethernet1/0/1 is the master port and Ethernet1/0/2 is the slave
port.
l
If Switch C is not configured with Monitor Link
group, when the link for the uplink port Ethernet1/0/1 on Switch C fails,
the links in the Smart Link group are not switched because the link for the
master port Ethernet1/0/1 of Switch A configured with Smart Link group operates
normally. Actually, however, the traffic on Switch A cannot be up-linked to Switch
E through the link of Ethernet1/0/1.
l
If Switch C is configured with Monitor Link group
and Monitor Link group detects that the link for the uplink port Ethernet1/0/1
fails, all the downlink ports in the group are shut down; therefore, Ethernet1/0/3
on Switch C is blocked. Now, Smart Link group configured on Switch A detects
that a link fault occurs on the master port Ethernet1/0/1. Then, Smart Link immediately
activates the slave port Ethernet1/0/2 so that traffic is switched to the backup
link.
l
Currently, member ports of a Monitor Link group
cannot be dynamic link aggregation groups.
l
If the uplink or downlink port in the Monitor
Link group is a link aggregation group, you cannot directly delete this
aggregation group or change this aggregation group into a dynamic aggregation
group. To delete this aggregation group, you must first unbind this aggregation
group from the Monitor Link.
Before configuring
a Monitor Link group, you must create a Monitor Link group and configure member
ports for it. A Monitor Link group consists of an uplink port and one or
multiple downlink ports. The uplink port can be a manually-configured or static
LACP link aggregation group, an Ethernet port, or a Smart Link group. The
downlink ports can be manually-configured link aggregation groups or static
LACP link aggregation groups, or Ethernet ports.
Table 2-1
Monitor Link configuration tasks
Table 2-2
Create a Monitor Link group
|
Operation
|
Command
|
Remarks
|
|
Enter system view
|
system-view
|
—
|
|
Create a Monitor Link group
|
monitor-link group group-id
|
Required
|
Table 2-3
Configure the uplink port
|
Operation
|
Command
|
Remarks
|
|
Enter system view
|
system-view
|
—
|
|
Enter the specified Monitor Link group
view
|
monitor-link group group-id
|
—
|
|
Configure the uplink port for the Monitor
Link group
|
Configure the specified link aggregation
group as the uplink port of the Monitor Link group
|
link-aggregation group group-id uplink
|
Required
Use any of the three approaches
|
|
Configure the specified Smart Link group
as the uplink port of the Monitor Link group
|
smart-link group group-id uplink
|
|
Configure the specified Ethernet port as
the uplink port of the Monitor Link group
|
Monitor Link group view
|
port interface-type
interface-number uplink
|
|
Ethernet port view
|
quit
|
|
interface interface-type interface-number
|
|
port monitor-link group group-id uplink
|
Table 2-4
Configure a downlink port
|
Operation
|
Command
|
Remarks
|
|
Enter system view
|
system-view
|
—
|
|
Enter the specified Monitor Link group
view
|
monitor-link group group-id
|
Required
|
|
Configure
a downlink port for the Monitor Link group
|
Configure
the specified link aggregation group as a downlink port of the Monitor Link
group
|
link-aggregation
group group-id
downlink
|
Required
Use either
approach
|
|
Configure
the specified Ethernet port as a downlink port of the Monitor Link group
|
Monitor
Link group view
|
port interface-type interface-number downlink
|
|
Ethernet
port view
|
quit
|
|
interface interface-type interface-number
|
|
port
monitor-link group group-id downlink
|
Caution:
l
A Smart Link/Monitor Link group with members cannot
be deleted. A Smart Link group as a Monitor Link group member cannot be
deleted.
l
The Smart Link/Monitor Link function and the remote
port mirroring function are incompatible with each other.
l
If a single port is specified as a Smart
Link/Monitor Link group member, do not use the lacp enable command on
the port or add the port to another dynamic link aggregation group because
doing so will cause the port to become an aggregation group member.
l
Using the copy command on a port does not copy
the Smart Link/Monitor Link group member information configured on the port to
any other port.
After the above-mentioned configuration,
you can use the display command in any view to display the information
about Monitor Link, so as to verify configuration result.
Table 2-5
Display Monitor Link configuration
|
Operation
|
Command
|
Remarks
|
|
Display the information about one or all
Monitor Link groups
|
display monitor-link group { group-id
| all }
|
You can use the display command in
any view.
|
I. Network requirements
As shown in Figure 2-3, the PCs access the server and
Internet through the switch. Configure Smart Link and Monitor Link to prevent
the PCs from failing to access the server and Internet due to uplink link or
port failure.
II. Network diagram
Figure 2-3 Network diagram for Monitor
Link configuration
III. Configuration procedure
1)
Enable Smart Link on Switch A and Switch B to
implement link redundancy backup. Perform the following configuration on Switch
A. The configuration on Switch B is the same as on Switch A.
# Enter system view.
<switchA> system-view
# Enter Ethernet port view. Disable STP on
Ethernet1/0/1 and Ethernet1/0/2.
[SwitchA] interface Ethernet 1/0/1
[SwitchA-Ethernet1/0/1] stp disable
[SwitchA-Ethernet1/0/1] quit
[SwitchA] interface Ethernet 1/0/2
[SwitchA-Ethernet1/0/2] stp disable
# Return to system view.
[SwitchA-Ethernet1/0/2] quit
# Create Smart Link group 1 and enter Smart
Link group view.
[SwitchA] smart-link group 1
# Configure Ethernet1/0/1 as the master
port of the Smart Link group and Ethernet1/0/2 as the slave port.
[SwitchA-smlk-group1] port Ethernet
1/0/1 master
[SwitchA-smlk-group1] port Ethernet
1/0/2 slave
# Configure to send flush messages in VLAN
1.
[SwitchA-smlk-group1] flush enable
control-vlan 1
2)
Enable Monitor Link on Switch C and Switch D and
enable the function of processing flush messages received from VLAN 1. Perform
the following configuration on Switch C. The operation procedure on Switch D is
the same as that performed on Switch C.
# Enter system view.
<SwitchC> system-view
# Create Monitor Link group 1 and enter
Monitor Link group view
[SwitchC] monitor-link group 1
# Configure Ethernet1/0/1 as the uplink
port of the Monitor Link group and Ethernet1/0/2 and Ethernet1/0/3 as the
downlink ports.
[SwitchC-mtlk-group1] port Ethernet
1/0/1 uplink
[SwitchC-mtlk-group1] port Ethernet
1/0/2 downlink
[SwitchC-mtlk-group1] port Ethernet
1/0/3 downlink
# Return to system view. Enable the
function of processing flush messages received from VLAN 1 on Ethernet1/0/2 and
Ethernet1/0/3.
[SwitchC-mtlk-group1] quit
[SwitchC] smart-link flush enable
control-vlan 1 port Ethernet 1/0/2 to Ethernet 1/0/3
3)
Enable the function of processing flush messages
received from VLAN 1 on Ethernet 1/0/10 and Ethernet 1/0/11 of Switch E.
# Enter system view.
<SwitchE> system-view
# Enable the function of processing flush
messages received from VLAN 1 on Ethernet 1/0/10 and Ethernet 1/0/11.
[SwitchE] smart-link flush enable
control-vlan 1 port Ethernet 1/0/10 to Ethernet 1/0/11
