Table of Contents

Chapter 1 Link Aggregation Configuration. 1-1

1.1 Overview. 1-1

1.2 LACP. 1-2

1.3 Link Aggregation Types. 1-2

1.3.1 Manual Aggregation and Static LACP Aggregation. 1-2

1.3.2 Dynamic LACP Aggregation. 1-3

1.4 Link Aggregation Load Sharing. 1-4

1.4.1 Types of Load Sharing. 1-4

1.4.2 Port States. 1-5

1.5 Link Aggregation Configuration. 1-5

1.5.1 Enabling/Disabling LACP on a Port 1-6

1.5.2 Configuring the LACP Slow Period Timer 1-7

1.5.3 Creating/Removing an Aggregation Group. 1-7

1.5.4 Adding/Removing an Ethernet Port to/from an Aggregation Group. 1-8

1.5.5 Enabling Aggregation Resource Extension. 1-9

1.5.6 Configuring Aggregation Group Description. 1-10

1.5.7 Configuring System Priority. 1-10

1.5.8 Configuring Port Priority. 1-11

1.6 Displaying and Maintaining Link Aggregation. 1-11

1.7 Link Aggregation Configuration Example. 1-12

 

Chapter 1  Link Aggregation Configuration

When configuring link aggregation, go to these sections for information you are interested in:

l           Overview

l           LACP

l           Link Aggregation Types

l           Link Aggregation Load Sharing

l           Link Aggregation Configuration

l           Displaying and Maintaining Link Aggregation

l           Link Aggregation Configuration Example

1.1  Overview

Link aggregation means aggregating several ports together into an aggregation group to implement load sharing among the member ports and to enhance the connection reliability. Link aggregation may be manual aggregation, dynamic LACP aggregation or static LACP aggregation. For the member ports in an aggregation group, their basic configurations are the same. That is, if one port in an aggregation group is a Trunk port, others must also be; when it turns into an Access port, then others must change to Access ports as well.

Basic configuration includes STP, QoS, VLAN, and port attribute settings. The STP settings include the STP enabling/disabling status, link attribute (point-to-point or not), STP priority, path cost, max transmission speed, loop protection, root protection, and port type (whether the port is an edge port or not). The QoS settings include traffic limiting, priority marking, default 802.1p priority, bandwidth assurance, congestion avoidance, traffic redirection, and traffic statistics. VLAN settings include permitted VLAN types and default VLAN ID. The port attribute settings include port link type, such as trunk, hybrid, access, and detection group-related configuration.

A device of the S9500 series can support up to 920 aggregation group IDs. IDs 1 though 31 indicate manual or static aggregation groups. IDs 32 through 192 are reserved. IDs 193 through 920 indicate dynamic aggregation groups, which are automatically generated by the system. The systems with MPLS VPN cards only support seven load balancing aggregation groups; those without MPLS VPN cards support 31 load balancing aggregation groups. The systems with FE boards using EX chips only supports seven load balancing aggregation groups.

 

 

1.2  LACP

Link Aggregation Control Protocol (LACP) based on the IEEE802.3ad standard can be used for dynamic link aggregation. An LACP-enabled port sends link aggregation control protocol data units (LACPDUs) to tell the peer about its system priority, system MAC address, port priority, port number and operation key. After receiving the information from the sender, the receiver compares it with the locally saved information about other ports, chooses member ports for the aggregation group and reaches agreement about whether a port can join or leave a dynamic aggregation group.

During link aggregation, LACP generates a configuration mix according to the port configuration (rate, duplex, basic configuration, management key), which is called an operation key. The management key of an LACP-enabled dynamic aggregation port is 0 by default. The management key of an LACP-enabled static aggregation port is the same as the aggregation group ID. In a dynamic aggregation group, the member ports have the same operation key. In manual and static aggregation groups, the selected ports have the same operation key.

1.3  Link Aggregation Types

The following three link aggregation types exist: manual aggregation, dynamic LACP aggregation, and static LACP aggregation.

1.3.1  Manual Aggregation and Static LACP Aggregation

Both manual aggregation and static LACP aggregation are configured manually, and cannot be added or removed automatically. A manual or static LACP aggregation group must contain at least a member port. If only one port is contained, you can remove the port only by removing the aggregation group. Member ports in a manual aggregation are LACP-disabled while those in a static aggregation are LACP-enabled. You cannot change the LACP status on them. When a static aggregation group is removed, the member ports will form one or more dynamic LACP aggregation groups with LACP enabled.

Ports in a manual/static aggregation group operating smoothly are in either selected state or standby state, although they may be in unselected state temporarily when the aggregation group is being established. Only the ports in selected state can transmit and receive data frames. Unselected state is an intermediate state which can be ignored. In an aggregation group, the selected port with the least port number serves as the master port, while others as member ports.

In a manual aggregation group, the ports that cannot be aggregated with the master port due to hardware limits (such as inter-board aggregation is unavailable) are in standby state.

In a static aggregation group, the system sets the ports to selected or standby state based on these rules:

l           Based on the descending order of priority levels from full duplex/high speed, full duplex/low speed, half duplex/high speed, to half duplex/low speed, the system sets the ports with the highest priority to selected state, and others to standby state.

l           Set a port to standby state, if the port is connected to a device different from the one connected to the master port or the port does not belong to the aggregation group to which the master port belongs.

l           The ports that cannot aggregate with the master port due to hardware restrictions (for example, cross-board aggregation restriction) are in standby state.

l           The ports with their basic configurations different from the configuration of the master port are in standby state.

An aggregation group can accommodate only a limited number of ports. If the number of selected ports in an aggregation group exceeds that allowed by the group, the ports with smaller port numbers are selected ports and others are standby ports. Both selected ports and standby ports can transmit and receive LACPDUs, but the standby ports cannot forward user service packets.

 

 

1.3.2  Dynamic LACP Aggregation

The system can create/delete dynamic LACP aggregations automatically, and you cannot add/delete member ports into/from a dynamic LACP aggregation. The system can aggregate a single port, which is called single port aggregation. On the members in a dynamic LACP aggregation, LACP is enabled. The system can only aggregate the ports with the same speed, duplex attribute, device connection, and basic configuration.

An aggregation group can accommodate a limited number of ports. If the number of the ports in an aggregation group exceeds that allowed by the group, the ports with smaller device ID (system priority + system MAC address) and smaller port ID (port priority + port number) are set as selected ports, and others as standby ports. If the maximum number is not exceeded, all the member ports are selected ports. Both selected and standby ports can transmit and receive LACPDUs, but standby ports cannot forward user service packets. In an aggregation group, the selected port with the least port number serves as the master port, while others as slave ports. When comparing device ID, the system compares system priority first, and then system MAC address in the case of the same system priority. The smaller device ID is regarded as higher priority. When comparing port ID, the system compares port priority first, and then port number in the case of the same port priority. The smaller port ID is regarded as higher priority. If the device ID changes to higher priority, the selected and standby state of the member ports in an aggregation group depends on the device port ID. You can also set system and port priority to define selected and standby ports.

1.4  Link Aggregation Load Sharing

1.4.1  Types of Load Sharing

A link aggregation group can be a load balancing aggregation group or a non-load balancing aggregation group. The S9500 series perform load sharing for IP packets (packets with the ETYPE field being 0800) based on destination and source IP addresses and for non-IP packets based on source and destination MAC addresses. As resources are limited, the system always allocates hardware aggregation resources to the load balancing aggregation groups with higher priority levels. When the load sharing aggregation resources are used up for existing aggregation groups, newly-created aggregation groups will be non-load sharing ones. The priority levels (in descending order) for allocating load sharing aggregation resources are as follows:

l           Aggregation group containing special ports that need hardware aggregation resources, such as non-wire-speed 10GE ports.

l           Aggregation group that probably reaches the maximum potential rate after the resources are allocated to it.

l           If the aggregation groups will operate at the same rate after the resources are allocated to them, the one with the least master port number has a higher priority.

l           Manual aggregation has a higher priority than static aggregation, and static aggregation has a higher priority level than dynamic aggregation.

l           Under the same conditions, an aggregation group that has occupied resources has a higher priority than an aggregation group waiting for resources.

When aggregation groups of higher priority levels appear, the aggregation groups of lower priority levels release their hardware resources. Single-port aggregation groups do not occupy hardware resources and can send and receive packets normally.

1.4.2  Port States

In an aggregation group, ports can be in selected or standby state. Only the selected ports can transmit and receive user service packets. The selected port with the least port number serves as the master port, while others as member ports (also known as slave ports).

Whether a port in an aggregation group is in selected or standby state is determined by the following rules.

l           Based on the descending order of priority levels from full duplex/high speed, full duplex/low speed, half duplex/high speed, to half duplex/low speed, the system sets the ports with the highest priority to selected state, and others to standby state.

l           The ports that cannot aggregate with the master port due to hardware limit are in standby state.

l           The ports with their basic configurations different from the configuration of the master port are in standby state.

An aggregation group can only accommodate a limited number of ports. If the number of selected ports in an aggregation group exceeds that allowed by the group, the ports with smaller port numbers are selected ports and others are standby ports. Selected ports can forward user packets, but the standby ports cannot.

A load sharing aggregation group can contain multiple selected ports, but a non-load sharing aggregation group can have only one selected port, with other ports being standby ports.

1.5  Link Aggregation Configuration

The following sections describe link aggregation tasks:

l           Enabling/Disabling LACP on a Port

l           Configuring the LACP Slow Period Timer

l           Creating/Removing an Aggregation Group

l           Adding/Removing an Ethernet Port to/from an Aggregation Group

l           Enabling Aggregation Resource Extension

l           Configuring Aggregation Group Description

l           Configuring System Priority

l           Configuring Port Priority

 

 

1.5.1  Enabling/Disabling LACP on a Port

You should first enable LACP at the ports before performing dynamic aggregation, so that both parties can agree on adding/deleting the ports into/from a dynamic LACP aggregation group.

Perform the following configuration to enable/disable LACP on a port:

To do…	Use the command…	Remarks
Enable LACP on a port	lacp enable	Available in Ethernet port view
Disable LACP on a port	undo lacp enable	Available in Ethernet port view

 

By default, LACP is not enabled on any port.

Note that:

l           You cannot enable LACP on mirroring ports, ports with a static MAC address, ports with static ARP, and ports with 802.1x enabled.

l           You cannot enable LACP on the ports in a manual aggregation group.

l           After a port with LACP disabled is added to a static LACP aggregation group, LACP will be enabled automatically on it.

 

 

1.5.2  Configuring the LACP Slow Period Timer

The slow period timer determines the interval for sending/receiving LACPDUs and the aging time when LACP negotiation is stable.

You can set the timer to a smaller value for fast link switchover desired in a scenario similar to the following:

Two LACP-enabled devices are connected through an intermediate transmit device and form an aggregate link group. In case a link connected to the intermediate device fails, traffic on the failed link will be switched to the other links in the link group after a period three times the slow period timer. To achieve faster switchover, you can decrease the slow period timer setting.

Do not tune the LACP slow period timer otherwise.

Follow these steps to tune the LACP slow period timer:

To do…	Use the command…	Remarks
Enter system view	system-view	—
Configure the LACP slow period timer	lacp timer slow interval	Required 30 seconds by default
Display LACP timer information	display lacp timer	Available in any view

 

 

1.5.3  Creating/Removing an Aggregation Group

You can create/remove a manual/static link aggregation group by performing the operations listed in the following table. After a link aggregation group is removed, all its member ports are disaggregated.

To do…	Use the command…	Remarks
Create a link aggregation group	link-aggregation group agg-id mode { manual | static }	Available in system view
Remove a link aggregation group	undo link-aggregation group agg-id	Available in system view

 

 

 

1.5.4  Adding/Removing an Ethernet Port to/from an Aggregation Group

Perform the following configuration to add/remove a port to/from an aggregation group:

To do…	Use the command…	Remarks
Add an Ethernet port to an aggregation group	port link-aggregation group agg-id	Available in Ethernet port view
Remove an Ethernet port from an aggregation port	undo port link-aggregation group	Available in Ethernet port view
Aggregate Ethernet ports	link-aggregation interface-type  interface-number1 to interface-type  interface-number2 [ both ]	Available in system view

 

 

1.5.5  Enabling Aggregation Resource Extension

Follow these steps to enable aggregation resource extension:

To do…	Use the command…	Remarks
Enter system view	system-view	—
Enable aggregation resource extension	link-aggregation extend	Required Aggregation resource extension is disabled by default.

 

By default, idle aggregation resources are allocated from 7 to 0 in the descending order for special port aggregation. With aggregation resource extension enabled, the system allocates idle aggregation resources from 31 to 0 in the descending order for special port aggregation.

Special ports include RprGE ports and non-wire-speed 10GE ports.

 

 

1.5.6  Configuring Aggregation Group Description

Perform the following configuration to configure the description of a manual/static aggregation group:

To do…	Use the command…	Remarks
Set an aggregation group description	link-aggregation group agg-id description alname	Available in system view
Delete an aggregation group description	undo link-aggregation group agg-id description	Available in system view

 

By default, an aggregation group has no description.

 

 

1.5.7  Configuring System Priority

LACP uses system IDs in determining whether the member ports are selected or standby for a dynamic LACP aggregation group. The system ID consists of two-byte system priority and six-byte system MAC, that is, system ID equals system priority plus system MAC. In comparing system IDs, the system first compares system priority values; if they are equal, then it compares system MAC addresses. The member with the lower system MAC address wins out.

Changing system priority may affect the priority levels of member ports, and then their selected or standby state.

Perform the following configuration to configure the system priority:

To do…	Use the command…	Remarks
Configure the system priority	lacp system-priority system-priority-value	Available in system view
Restore the default system priority	undo lacp system-priority	Available in system view

 

The default system priority is 32768.

1.5.8  Configuring Port Priority

LACP compares system IDs first and then port IDs (if the system IDs are the same) in determining if the member ports are selected or standby ones for a dynamic LACP aggregation group. If the number of ports in an aggregation group exceeds that allowed by the group, the ports with smaller port IDs are selected ports and others are standby ports. The port ID consists of two-byte port priority and two-byte port number, that is, port ID equals port priority plus port number. The system first compares port priority values and then port numbers and a smaller port ID is given priority.

Perform the following configuration to configure the port priority:

To do…	Use the command…	Remarks
Configure the port priority	lacp port-priority port-priority-value	Available Ethernet port view
Restore the default port priority	undo lacp port-priority	Available Ethernet port view

 

The default port priority is 32768.

1.6  Displaying and Maintaining Link Aggregation

To do…	Use the command…	Remarks
Display the summary of all aggregation groups	display link-aggregation summary	Available in any view
Display detailed information of a specific or all aggregation groups	display link-aggregation verbose [ agg-id ]	Available in any view
Display the local device ID	display lacp system-id	Available in any view
Display LACP timer information	display lacp timer	Available in any view
Display detailed link aggregation information on specified port(s)	display link-aggregation interface interface-type interface-number [ to interface-type interface-number ]	Available in any view
Clear the LACP statistics for specified port(s)	reset lacp statistics [ interface interface-type interface-number [ to interface-type interface-number ] ]	Available in user view
Enable LACP state debugging	debugging lacp state [ interface interface-type interface-number [ to interface-type interface-number ] ] { { actor-churn | mux | partner-churn | ptx | rx }* | all }	Available in user view
Enable LACP packet debugging	debugging lacp packet [ interface interface-type interface-number [ to interface-type interface-number ] ]	Available in user view
Enable link aggregation error debugging	debugging link-aggregation error	Available in user view
Enable link aggregation event debugging	debugging link-aggregation event	Available in user view

 

1.7  Link Aggregation Configuration Example

I. Configuration task

Aggregate Ethernet 2/1/1 and Ethernet 2/1/2 in manual mode, static LACP aggregation mode, and dynamic LACP aggregation mode respectively to increase bandwidth between Switch A and Switch B and achieve LPU redundancy.

II. Configuration prerequisites

None

III. Network diagram

Figure 1-1 Network diagram for link aggregation configuration

IV. Configuration procedure

The following only lists the configuration for switch A, and that on switch B is similar.

1)         Manual aggregation

# Create aggregation group 1.

[Switch A] link-aggregation group 1 mode manual

# Add Ethernet 2/1/1 and Ethernet 2/1/2 to aggregation group 1.

[Switch A] interface ethernet 2/1/1

[Switch A-Ethernet2/1/1] port link-aggregation group 1

[Switch A-Ethernet2/1/1] interface ethernet 2/1/2

[Switch A-Ethernet2/1/2] port link-aggregation group 1

 

 

2)         Static LACP aggregation

# Create aggregation group 1.

[Switch A] link-aggregation group 1 mode static

# Add Ethernet 2/1/1 and Ethernet 2/1/2 to aggregation group 1.

[Switch A] interface ethernet 2/1/1

[Switch A-Ethernet2/1/1] port link-aggregation group 1

[Switch A-Ethernet2/1/1] interface ethernet 2/1/2

[Switch A-Ethernet2/1/2] port link-aggregation group 1

3)         Dynamic LACP aggregation

# Enable LACP on Ethernet 2/1/1 and Ethernet 2/1/2.

[Switch A] interface ethernet 2/1/1

[Switch A-Ethernet2/1/1] lacp enable

[Switch A-Ethernet2/1/1] interface ethernet 2/1/2

[Switch A-Ethernet2/1/2] lacp enable