05-Link Aggregation Configuration
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Table of Contents
1 Link Aggregation Configuration
Basic Concepts of Link Aggregation
Load Sharing Mode of an Aggregation Group
Link Aggregation Configuration Task List
Configuring an Aggregation Group
Configuring a Static Aggregation Group
Configuring a Dynamic Aggregation Group
Configuring an Aggregate Interface
Configuring the Description of an Aggregate Interface
Enabling LinkUp/LinkDown Trap Generation for an Aggregate Interface
Shutting Down an Aggregate Interface
Configuring a Load Sharing Mode for Load-Sharing Link Aggregation Groups
Displaying and Maintaining Link Aggregation
Link Aggregation Configuration Examples
Layer-2 Static Aggregation Configuration Example
Layer-2 Dynamic Aggregation Configuration Example
When configuring link aggregation, go to these sections for information you are interested in:
l Overview
l Link Aggregation Configuration Task List
l Configuring an Aggregate Interface
l Configuring an Aggregation Group
l Configuring a Load Sharing Mode for Load-Sharing Link Aggregation Groups
l Displaying and Maintaining Link Aggregation
l Link Aggregation Configuration Examples
Link aggregation aggregates multiple physical Ethernet ports into one logical link, also called an aggregation group.
It allows you to increase bandwidth by distributing traffic across the member ports in the aggregation group. In addition, it provides reliable connectivity because these member ports can dynamically back up each other.
An aggregate interface is a logical Layer-2 or Layer-3 aggregate interface.
An aggregation group is a collection of Ethernet interfaces. When you create an aggregate interface, an aggregation group numbered the same is created automatically depending on the type of the aggregate interface:
l If the aggregate interface is a Layer 2 interface, a Layer-2 aggregation group is created. You can assign only Layer-2 Ethernet ports to the group.
l If the aggregate interface is a Layer-3 interface, a Layer-3 aggregation group is created. You can assign only Layer-3 Ethernet interfaces to the group.
Currently, the S3600 series EPON OLT switches only support Layer 2 aggregation groups, which are automatically generated as you create Layer 2 aggregate interfaces and these Layer 2 aggregation groups can only contain Ethernet ports as member ports.
A member port in an aggregation group can be in one of the following two states:
l Selected: a selected port can forward user traffic.
l Unselected: an unselected port cannot forward user traffic.
The rate of an aggregate interface is the sum of the selected member ports’ rates. The duplex mode of an aggregate interface is consistent with that of the selected member ports. Note that all selected member ports use the same duplex mode.
For how the state of a member port is determined, refer to Static aggregation mode and Dynamic aggregation mode.
The Link Aggregation Control Protocol (LACP) is defined in IEEE 802.3ad. It uses link aggregation control protocol data units (LACPDUs) for information exchange between LACP-enabled devices.
LACP is automatically enabled on interfaces in a dynamic aggregation group. For information about dynamic aggregation groups, refer to Dynamic aggregation mode. An LACP-enabled interface sends LACPDUs to notify the remote system (the partner) of its system LACP priority, system MAC address, LACP port priority, port number, and operational key. Upon receiving an LACPDU, the partner compares the received information with the information received on other interfaces to determine the interfaces that can operate as selected interfaces. This allows the two systems to reach an agreement on which link aggregation member ports should be placed in selected state.
When aggregating ports, link aggregation control automatically assigns each port an operational key based on port attributes (including the port rate, duplex mode and link state configuration), and the class-two configurations listed in Table 1-1.
Table 1-1 Class-two configurations
|
Type |
Considerations |
|
Port isolation |
Whether a port has joined an isolation group. |
|
QinQ |
QinQ enable state (enable/disable), outer VLAN tags to be added, inner-to-outer VLAN priority mappings, inner-to-outer VLAN tag mappings, inner VLAN ID substitution mappings |
|
VLAN |
Permitted VLAN IDs, default VLAN, link type (trunk, hybrid, or access), IP subnet-based VLAN configuration, protocol-based VLAN configuration, tag mode |
|
MAC address learning |
MAC address learning capability, MAC address learning limit, forwarding of frames with unknown destination MAC addresses after the upper limit of the MAC address table is reached |
l Some configurations are called class-one configurations. Such configurations, for example, GVRP and MSTP, can be configured on aggregate interfaces and member ports but are not considered during operational key calculation.
l The change of a class-two configuration setting may affect the select state of link aggregation member ports and thus the ongoing service. To prevent unconsidered change, a message warning of the hazard will be displayed when you attempt to change a class-two setting, upon which you can decide whether to continue your change operation.
In the same aggregation group, member ports different in the above-mentioned configurations are assigned different operational keys. A member port different from the aggregate interface in the above-mentioned configurations cannot be a selected port.
In an aggregation group, all selected ports are assigned the same operational key.
Depending on the link aggregation procedure, link aggregation operates in one of the following two modes:
LACP is disabled on the member ports in a static aggregation group. In a static aggregation group, the system sets a port to selected or unselected state by the following rules:
l Select a port as the reference port from the ports that are in up state and with the same class-two configurations as the corresponding aggregate interface. These ports are selected in the order of full duplex/high speed, full duplex/low speed, half duplex/high speed, and half duplex/low speed, with full duplex/high speed being the most preferred. If two ports with the same duplex mode/speed pair are present, the one with the lower port number wins out.
l Consider the ports in up state with the same port attributes and class-two configurations as the reference port as candidate selected ports, and set all others in the unselected state.
l Static aggregation limits the number of selected ports in an aggregation group. When the number of the candidate selected ports is under the limit, all the candidate selected ports become selected ports. When the limit is exceeded, set the candidate selected ports with smaller port numbers in the selected state and those with greater port numbers in the unselected state.
l If all the member ports are down, set their states to unselected.
l Set the ports that cannot aggregate with the reference port to the unselected state.
A port that joins the aggregation group after the limit on the number of selected ports has been reached will not be placed in the selected state even if it should be in normal cases. This can prevent the ongoing traffic on the current selected ports from being interrupted. You should avoid the situation however, as this may cause the selected/unselected state of a port to change after a reboot.
LACP is enabled on member ports in a dynamic aggregation group.
In a dynamic aggregation group,
l A selected port can receive and transmit LACPDUs.
l An unselected port can receive and send LACPDUs only if it is up and with the same configurations as those on the aggregate interface.
In a dynamic aggregation group, the system sets the ports to selected or unselected state in the following steps:
1) The local system (the actor) negotiates with the remote system (the partner) to determine port state based on the port IDs on the end with the preferred system ID. The following is the detailed negotiation procedure:
l Compare the system ID (comprising the system LACP priority and the system MAC address) of the actor with that of the partner. The system with the lower LACP priority wins out. If they are the same, compare the system MAC addresses. The system with the smaller MAC address wins out.
l Compare the port IDs of the ports on the system with the smaller system ID. A port ID comprises a port LACP priority and a port number. First compare the port LACP priorities. The port with the lower LACP priority wins out. If two ports are with the same LACP priority, compare their port numbers. The port with the smaller port ID, that is, the port with smaller port number, is selected as the reference port.
l If a port (in up state) is with the same port attributes and class-two configuration as the reference port, and the peer port of the port is with the same port attributes and class-two configurations as the peer port of the reference port, consider the port as a candidate selected port; otherwise set the port to the unselected state.
l The number of selected ports that an aggregation group can contain is limited. When the number of candidate selected ports is under the limit, all the candidate selected ports are set to selected state. When the limit is exceeded, the system selects the candidate selected ports with smaller port IDs as the selected ports, and set other candidate selected ports to unselected state. At the same time, the peer device, being aware of the changes, changes the state of its ports accordingly.
2) Set the ports that cannot aggregate with the reference port to the unselected state.
For static and dynamic aggregation modes:
l In an aggregation group, the port to be a selected port must be the same as the reference port in port attributes, and class-two configurations. To keep these configurations consistent, you should configure the port manually.
l Because changing a port attribute or class-two configuration setting of a port may cause the select state of the port and other member ports to change and thus affects services, you are recommended to do that with caution.
A link aggregation groups operates in load sharing aggregation mode or non-load sharing mode.
The link aggregation groups created on the S3600 series EPON OLT switches always operate in load sharing aggregation mode, even when they contain only one member port.
Complete the following tasks to configure link aggregation:
|
Task |
Remarks |
|
|
Select either task |
||
|
Optional |
||
|
Enabling LinkUp/LinkDown Trap Generation for an Aggregate Interface |
Optional |
|
|
Optional |
||
|
Configuring a Load Sharing Mode for Load-Sharing Link Aggregation Groups |
Optional |
|
l These ports cannot be assigned to a Layer 2 aggregation group: RRPP-enabled ports.
l You are discouraged to assign reflector ports of port mirroring to an aggregation group. For more information about reflector ports, refer to Port Mirroring Configuration in the Access Volume.
Follow these steps to configure a static aggregation group:
|
To do... |
Use the command... |
Remarks |
|
Enter system view |
system-view |
— |
|
Create a Layer 2 aggregate interface and enter the Layer 2 aggregate interface view |
interface bridge-aggregation interface-number |
Required When you create a Layer 2 aggregate interface, a Layer 2 static aggregation group numbered the same is created automatically. |
|
Exit to system view |
quit |
— |
|
Enter Layer 2 Ethernet interface view |
interface interface-type interface-number |
Required Repeat the two steps to assign multiple Ethernet ports to the aggregation group. |
|
Assign the Ethernet interface to the aggregation group |
port link-aggregation group number |
l Removing a Layer 2 aggregate interface also removes the corresponding aggregation group. At the same time, the member ports of the aggregation group, if any, leave the aggregation group.
l To guarantee a successful static aggregation, ensure that the ports at the two ends of each link to be aggregated are consistent in the selected/unselected state.
Follow these steps to configure a Layer 2 dynamic aggregation group:
|
To do... |
Use the command... |
Remarks |
|
Enter system view |
system-view |
— |
|
Set the system LACP priority |
lacp system-priority system-priority |
Optional By default, the system LACP priority is 32768. Changing the system LACP priority may affect the selected/unselected state of the ports in a dynamic aggregation group. |
|
Create a Layer 2 aggregate interface and enter the Layer 2 aggregate interface view |
interface bridge-aggregation interface-number |
Required When you create a Layer 2 aggregate interface, a Layer 2 static aggregation group numbered the same is created automatically. |
|
Configure the aggregation group to work in dynamic aggregation mode |
link-aggregation mode dynamic |
Required By default, an aggregation group works in static aggregation mode. |
|
Exit to system view |
quit |
— |
|
Enter Layer 2 Ethernet interface view |
interface interface-type interface-number |
Required Repeat the two steps to assign multiple Ethernet interfaces to the aggregation group. |
|
Assign the Ethernet interface to the aggregation group |
port link-aggregation group number |
|
|
Assign the port a LACP priority |
lacp port-priority port-priority |
Optional By default, the LACP priority of a port is 32768. Changing the LACP priority of a port may affect the selected/unselected state of the ports in the dynamic aggregation group. |
l Removing a dynamic aggregate interface also removes the corresponding aggregation group. At the same time, the member ports of the aggregation group, if any, leave the aggregation group.
l To guarantee a successful dynamic aggregation, ensure that the peer ports of the ports aggregated at one end are also aggregated. The two ends can automatically negotiate the selected state of the ports.
You can perform the following configurations for an aggregate interface:
l Configuring the Description of an Aggregate Interface
l Enabling LinkUp/LinkDown Trap Generation for an Aggregate Interface
l Shutting Down an Aggregate Interface
Follow these steps to configure the description of an aggregate interface:
|
To do... |
Use the command... |
Remarks |
|
Enter system view |
system-view |
— |
|
Enter aggregate interface view |
interface bridge-aggregation interface-number |
— |
|
Configure the description of the aggregate interface |
description text |
Optional By default, the description of an interface is interface-name Interface, such as Bridge-Aggregation1 Interface. |
To enable an aggregate interface to generate linkUp/linkDown trap messages when the state of the interface changes, you should enable linkUp/linkDown trap generation on the aggregate interface.
Follow these steps to enable linkUp/linkDown trap generation for an aggregate interface:
|
To do... |
Use the command... |
Remarks |
|
Enter system view |
system-view |
— |
|
Enable the trap function globally |
snmp-agent trap enable [ standard [ linkdown | linkup ] * ] |
Optional By default, linkUp/linkDown trap generation is enabled globally and on all interfaces. |
|
Enter aggregate interface view |
interface bridge-aggregation interface-number |
— |
|
Enable linkUp/linkDown trap generation for the aggregate interface |
enable snmp trap updown |
Optional Enabled by default |
Shutting down or bringing up an aggregate interface affects the selected state of the ports in the corresponding aggregation group. When an aggregate interface is shut down, all selected ports in its aggregation group become unselected; when the aggregate interface is brought up, the selected state of the ports in the corresponding aggregation group is re-calculated.
Follow these steps to shut down an aggregate interface:
|
To do... |
Use the command... |
Remarks |
|
Enter system view |
system-view |
— |
|
Enter aggregate interface view |
interface bridge-aggregation interface-number |
— |
|
Shut down the aggregate interface |
shutdown |
Required By default, aggregate interfaces are up. |
You are recommended not to perform the undo shutdown and then shutdown commands on a member port of the aggregation group corresponding to an aggregate interface that is already shut down. Otherwise, when the member port is brought up, the selected state of the remote port will be affected.
The hash algorithm is adopted to calculate load sharing for load-sharing link aggregation groups. Hash keys used for calculation could be service port numbers, IP addresses, MAC addresses, incoming ports, or any combinations of them. One hash key or a combination of multiple hash keys represents a load sharing mode. You can change the load sharing mode of a link aggregation group for different types of traffic as needed.
Follow these steps to configure the global load sharing mode for link aggregation groups:
|
To do... |
Use the command... |
Remarks |
|
Enter system view |
system-view |
— |
|
Configure the global link aggregation load sharing mode |
link-aggregation load-sharing mode { destination-ip | destination-mac | destination-port | ingress-port | source-ip | source-mac | source-port } * |
Optional By default, the hash keys for Layer 2 packets are source/destination MAC addresses, and those for Layer-3 packets are source/destination IP addresses. This command applies only to the load sharing mode of Layer 3 packets. After you configure this command, the Layer 3 load sharing modes in all link aggregation groups change accordingly, but the Layer 2 load sharing modes will not be affected. The default source/destination MAC addresses will still be used as the hash keys |
Currently, the S3600 series EPON OLT switches do not support load sharing calculation based on source ports, destination ports, or the combination of MAC and IP addresses. The ingress-port keyword can be used as the hash key for load sharing calculation when combined with MAC addresses, but not when combined with source ports, destination ports, or IP addresses, or alone. If you configure load sharing for link aggregation groups in modes that are not supported by the S3600 series, the system generates prompts to remind you that the load sharing modes you are configuring are not supported.
|
To do... |
Use the command... |
Remarks |
|
Display the local system ID |
display lacp system-id |
Available in any view |
|
Display the global or aggregation group-specific load sharing mode |
display link-aggregation load-sharing mode |
Available in any view |
|
Display link aggregation details of ports |
display link-aggregation member-port [ interface-type interface-number [ to interface-type interface-number ] ] |
Available in any view |
|
Display the summary information of all aggregation groups |
display link-aggregation summary |
Available in any view |
|
Display detailed information of aggregation groups |
display link-aggregation verbose [ bridge-aggregation [ interface-number ] ] |
Available in any view |
|
Clear the statistics of the specified aggregate interfaces |
reset counters interface [ bridge-aggregation [ interface-number ] ] |
Available in user view |
|
Clear the LACP statistics of ports |
reset lacp statistics [ interface interface-type interface-number [ to interface-type interface-number ] ] |
Available in user view |
As shown in Figure 1-1, Device A and Device B are connected through their respective Layer-2 Ethernet ports GigabitEthernet 1/1/1 to GigabitEthernet 1/1/3.
Aggregate the ports on each device to form a static link aggregation group, thus balancing incoming/outgoing traffic across the member ports. In addition, perform load sharing based on source and destination MAC addresses.
Figure 1-1 Network diagram for Layer-2 static aggregation
1) Configure Device A
# Configure the device to perform load sharing based on source and destination MAC addresses for link aggregation groups.
<DeviceA> system-view
[DeviceA] link-aggregation load-sharing mode source-mac destination-mac
# Create Layer-2 aggregate interface Bridge-aggregation 1.
[DeviceA] interface bridge-aggregation 1
[DeviceA-Bridge-Aggregation1] quit
# Assign Layer-2 Ethernet interfaces GigabitEthernet 1/1/1 through GigabitEthernet 1/1/3 to aggregation group 1.
[DeviceA] interface gigabitethernet 1/1/1
[DeviceA-GigabitEthernet1/1/1] port link-aggregation group 1
[DeviceA-GigabitEthernet1/1/1] quit
[DeviceA] interface gigabitethernet 1/1/2
[DeviceA-GigabitEthernet1/1/2] port link-aggregation group 1
[DeviceA-GigabitEthernet1/1/2] quit
[DeviceA] interface gigabitethernet 1/1/3
[DeviceA-GigabitEthernet1/1/3] port link-aggregation group 1
2) Configure Device B
Follow the same configuration procedure performed on Device A to configure Device B.
As shown in Figure 1-2, Device A and Device B are connected through their respective Layer-2 Ethernet ports GigabitEthernet 1/1/1 to GigabitEthernet 1/1/3.
Aggregate the ports on each device to form a dynamic link aggregation group, thus balancing incoming/outgoing traffic across the member ports. In addition, perform load sharing based on source and destination MAC addresses.
Figure 1-2 Network diagram for Layer-2 dynamic aggregation
1) Configure Device A
# Configure the device to perform load sharing based on source and destination MAC addresses for link aggregation groups.
<DeviceA> system-view
[DeviceA] link-aggregation load-sharing mode source-mac destination-mac
# Create a Layer-2 aggregate interface Bridge-Aggregation 1 and configure the interface to work in dynamic aggregation mode.
[DeviceA] interface bridge-aggregation 1
[DeviceA-Bridge-Aggregation1] link-aggregation mode dynamic
[DeviceA-Bridge-Aggregation1] quit
# Assign Layer-2 Ethernet interfaces GigabitEthernet 1/1/1 through GigabitEthernet 1/1/3 to aggregation group 1.
[DeviceA] interface gigabitethernet 1/1/1
[DeviceA-GigabitEthernet1/1/1] port link-aggregation group 1
[DeviceA-GigabitEthernet1/1/1] quit
[DeviceA] interface gigabitethernet 1/1/2
[DeviceA-GigabitEthernet1/1/2] port link-aggregation group 1
[DeviceA-GigabitEthernet1/1/2] quit
[DeviceA] interface gigabitethernet 1/1/3
[DeviceA-GigabitEthernet1/1/3] port link-aggregation group 1
2) Configure Device B
Follow the same configuration procedure performed on Device A to configure Device B.
