Link aggregation means aggregating several links together to form an aggregation group, so as to implement outgoing/incoming load sharing among the member ports in the group and to enhance the connection reliability.

Depending on different aggregation modes, aggregation groups fall into three types: manual, static LACP, and dynamic LACP. Depending on whether or not load sharing is implemented, aggregation groups can be load-sharing or non-load-sharing aggregation groups.

& Note:

Up to 384 aggregation groups can be created in a system, where up to 64 load-sharing aggregation groups can be created.

For the member ports in an aggregation group, their basic configuration must be the same. The basic configuration includes STP, QoS, VLAN, port attributes and other associated settings.

l STP configuration, including STP status (enabled or disabled), link attribute (point-to-point or non-point-to-point), STP priority, STP path cost, STP standard packet format, maximum transmission speed, loop guard status, root guard status, edge port or not.

l QoS configuration, including traffic rate limiting, priority marking, default 802.1p priority, bandwidth assurance, congestion avoidance, traffic redirection, traffic statistics, and so on.

l VLAN configuration, including permitted VLANs, and default VLAN ID.

l Port attribute configuration, including port rate, duplex mode, and link type (Trunk, Hybrid or Access). The ports for a manual or static aggregation group must have the same link type, and the ports for a dynamic aggregation group must have the same rate, duplex mode and link type.

1.1.2 Introduction to LACP

The purpose of Link Aggregation Control Protocol (LACP) is to implement dynamic link aggregation and deaggregation. This protocol is based on IEEE802.3ad and uses LACP data units (LACPDUs) to interact with its peer.

After LACP is enabled on a port, LACP notifies the following information of the port to its peer by sending LACPDUs: priority and MAC address of this system, port priority, port number and operation key of the port. After the peer port receives the information, the peer collects the information received by all its ports and compares the information to determine the ports that can be aggregated.

1.1.3 Operation Key

An operation key is a configuration combination generated by the system depending on the configurations of the port (rate, duplex mode, basic configuration, and management key) when the port is aggregated.

1) The selected ports in a manual/static aggregation group have the same operation key.

2) The management key of an LACP-enabled static aggregation port is equal to its aggregation group ID.

3) The management key of an LACP-enabled dynamic aggregation port is zero by default.

4) The member ports in a dynamic aggregation group have the same operation key.

1.1.4 Manual Aggregation Group

I. Introduction to manual aggregation group

A manual aggregation group is manually created. All its member ports are manually added and can be manually removed (it inhibits the system from automatically adding/removing ports to/from it). Each manual aggregation group must contain at least one port. When a manual aggregation group contains only one port, you cannot remove the port unless you remove the whole aggregation group.

LACP is disabled on the ports of manual aggregation groups, and you cannot enable LACP on a port of a manual aggregation group.

II. Port status in manual aggregation group

A port in a manual aggregation group can be in one of the two states: selected or standby. The selected port with the minimum port number serves as the master port of the group, and other selected ports serve as member ports of the group.

There is a limit on the number of selected ports in an aggregation group. Therefore, if the number of ports that can be set as selected ports in an aggregation group exceeds the maximum number supported by the device, the system will choose the ports with lower port numbers as the selected ports, and set others as standby ports.

III. Requirements on ports for manual aggregation

Generally, there is no limit on the rate and duplex mode of the ports you want to add to a manual aggregation group. However, note the following cases:

l For the ports which are initially down, there is no limit on the rate and duplex mode of the ports when they are added to an aggregation group;

l For the currently down ports which used to be up and whose rate and duplex mode are specified in the negotiation mode or mandatory mode, the rate and duplex mode of each port must be the same as those of the selected ports in the manual aggregation group;

l When the rate and duplex mode of a port in the manual aggregation group change, the system does not deaggregate the aggregation group and all the ports in the group work normally. However, if the rate of the master port decreases and the duplex mode of the master port changes, packet loss may occur on the port.

1.1.5 Static LACP Aggregation Group

I. Introduction to static LACP aggregation

A static LACP aggregation group is also manually created. All its member ports are manually added and can be manually removed (it inhibits the system from automatically adding/removing ports to/from it). Each static aggregation group must contain at least one port. When a static aggregation group contains only one port, you cannot remove the port unless you remove the whole aggregation group.

LACP is enabled on the member ports of static aggregation groups, and you cannot disable LACP on such a port. When you remove a static aggregation group, the system will remain the member ports of the group in LACP-enabled state and re-aggregate the ports to form one or more dynamic LACP aggregation groups.

II. Port status of static aggregation group

A port in a static aggregation group can be in one of the two states: selected or standby. Both the selected and the standby ports can transceive LACP protocol packets however, the standby ports cannot forward user packets.

& Note:

In an aggregation group, the selected port with the minimum port number serves as the master port of the group, and other selected ports serve as member ports of the group.

In a static aggregation group, the system sets the ports to selected or standby state according to the following rules:

l The system sets the "most preferred" ports (that is, the ports take most precedence over other ports) to selected state, and others to standby state. Port precedence descends in the following order: full duplex/high speed, full duplex/low speed, half duplex/high speed, half duplex/low speed.

l The system sets the state of the following ports to "standby": port connected to a peer device different from the one the master port is connected to; port connected to the same peer device as the master port but to a peer port that is not in the same aggregation group as the peer port of the master port.

l The system sets the ports unable to aggregate with the master port (due to some hardware limit, for example, cross-board aggregation unavailability) to standby state.

l The system sets the ports with basic port configuration different from that of the master port to standby state.

There is a limit on the number of selected ports in an aggregation group. Therefore, if the number of the member ports in an aggregation group exceeds the maximum number supported by the device, the system will choose the member ports with lower port numbers as the selected ports, and set others as standby ports.

& Note:

For the restriction of LPU types on link aggregation, refer to Table 1-2 and Table 1-3.

1.1.6 Dynamic LACP Aggregation Group

I. Introduction to dynamic LACP aggregation group

A dynamic LACP aggregation group is automatically created and removed by the system. Users cannot add/remove ports to/from it. Ports can be aggregated into a dynamic aggregation group only when they are connected to the same peer device and have the same basic configuration, and the same rate and duplex mode.

Besides multiple-port aggregation groups, the system is also able to create single-port aggregation groups, each of which contains only one port. LACP is enabled on the member ports of dynamic aggregation groups.

II. Port status of dynamic aggregation group

A port in a dynamic aggregation group can be in one of the two states: selected or standby. In a dynamic aggregation group, both the selected and the standby ports can transceive LACP protocol packets; however, the standby ports cannot forward user packets.

There is a limit on the number of selected ports in an aggregation group. Therefore, if the number of the member ports in an aggregation group exceeds the maximum number supported by the device, the system will negotiate with its peer end, to determine the states of the member ports according to the IDs of ports of the preferred device (that is, the device with smaller system ID). The following is the negotiation procedure:

1) Compare device IDs (system priority + system MAC address) between the two parties. First compare the system priority of the two devices. If the system priorities are equal, compare the MAC address of the two systems. The device with smaller device ID will be considered as the preferred one.

2) Compare port IDs (port priority + port number) on the preferred device. The comparison between two port IDs is as follows: First compare the two port priorities, then the two port numbers if the two port priorities are equal; the port with smaller port ID is a selected port and the other port is a standby port.

In an aggregation group, the selected port with the minimum port number serves as the master port of the group, and other selected ports serve as member ports of the group.

& Note:

l The down ports in a static aggregation group or dynamic aggregation group are standby ports, which is different in manual aggregation groups.

l For the restriction of LPU types on link aggregation, refer to Table 1-2 and Table 1-3.

1.1.7 Restriction of LPU types on Link Aggregation

Table 1-1 lists link aggregation types and related descriptions.

& Note:

Type-A LPUs include the following specifications: LS81FT48A, LS81FM24A, LS81FS24A, LS81GB8UA and LS81GT8UA.

Table 1-1 Link aggregation types and related descriptions

Aggregation type	Basic description	Specific description
Manual aggregation	Support up to 384 aggregation groups, including 64 load sharing aggregation groups	l For type-A LPUs, an aggregation group supports up to 8 selected GE ports or 16 selected FE ports l For non-type-A LPUs, an aggregation group supports up to 8 selected GE ports or 8 selected FE ports
Static/dynamic aggregation	l For type-A LPUs, an aggregation group supports up to 8 selected GE ports l For type-A LPUs, an aggregation group supports up to 24 FE ports, including up to 16 selected ones l For non-type-A LPUs, an aggregation group supports up to 48 ports, including up to 8 selected ones

Aggregation type

Basic description

Specific description

Manual aggregation

Support up to 384 aggregation groups, including 64 load sharing aggregation groups

l For type-A LPUs, an aggregation group supports up to 8 selected GE ports or 16 selected FE ports

l For non-type-A LPUs, an aggregation group supports up to 8 selected GE ports or 8 selected FE ports

Static/dynamic aggregation

l For type-A LPUs, an aggregation group supports up to 8 selected GE ports

l For type-A LPUs, an aggregation group supports up to 24 FE ports, including up to 16 selected ones

l For non-type-A LPUs, an aggregation group supports up to 48 ports, including up to 8 selected ones

Table 1-2 and Table 1-3 describe the restriction of type-A LPUs and non-type-A LPUs on link aggregation respectively.

Table 1-2 Restriction of type-A LPUs on link aggregation

LPU type	Cross-chip aggregation	Aggregation type	LPU specification	Maximum number of ports in an aggregation group	Maximum number of selected ports in an aggregation group
Type-A LPU	Not supported	Manual aggregation	LS81FT48A	16	16
			LS81FM24A/LS81FS24A	16	16
			LS81GB8UA/LS81GT8UA	8	8
		Static/dynamic aggregation	LS81FT48A	24	16
			LS81FM24A/LS81FS24A	24	16
			LS81GB8UA/LS81GT8UA	8	8

Table 1-3 Restriction of non-type-A LPUs on link aggregation

LPU type	Cross-chip aggregation	Aggregation type	Maximum number of ports in an aggregation group	Maximum number of selected ports in an aggregation group
Non-type-A LPU	Supported	Manual aggregation	8	8
Non-type-A LPU	Supported	Static/dynamic aggregation	The number of ports on the LPU	8

1.1.8 Aggregation Group Categories

Depending on whether or not load sharing is implemented, aggregation groups can be load-sharing or non-load-sharing aggregation groups.

In general, the system only provides limited load-sharing aggregation resources (currently up to 64 load-sharing aggregation groups can be created), so the system needs to reasonably allocate the resources among different aggregation groups.

The system always allocates hardware aggregation resources to the aggregation groups with higher priorities. When load-sharing aggregation resources are used up by existing aggregation groups, newly-created aggregation groups will be non-load-sharing ones.

The priorities of aggregation groups for allocating load-sharing aggregation resources are as follows:

l An aggregation group containing special ports (such as 10GE port) which require hardware aggregation resources has higher priority than any aggregation group containing no special port.

l A manual or static aggregation group has higher priority than a dynamic aggregation group (unless the latter contains special ports while the former does not).

l For two aggregation groups, the one that might gain higher speed if resources were allocated to it has higher priority than the other one.

l If the two groups can gain the same speed after resources are allocated to them, the one with smaller master port number has higher priority than the other one.

When an aggregation group of higher priority appears, the aggregation groups of lower priorities release their hardware resources. For single-port aggregation groups, if they can transceive packets normally without occupying aggregation resources, they will not occupy hardware aggregation resources.

Caution:

A load-sharing aggregation group contains at least two selected ports, however, a non-load-sharing aggregation group can have one selected port at most and others are standby ports.

1.2 Link Aggregation Configuration

Caution:

l The following ports cannot be added to an aggregation group: destination ports to be mirrored to, reflection ports of remote mirroring, ports configured with static MAC addresses, static-ARP-enabled ports, and 802.1x-enabled ports.

l Ports where the IP-MAC address binding is configured cannot be added to an aggregation group.

Note that:

1) When creating an aggregation group:

l If the aggregation group you are creating already exists but contains no port, its type will change to the type you set.

l If the aggregation group you are creating already exists and contains ports, the possible type changes may be: changing from dynamic or static to manual, and changing from dynamic to static; and no other kinds of type change can occur.

l When you change a dynamic/static group to a manual group, the system will automatically disable LACP on the member ports. When you change a dynamic group to a static group, the system will remain the member ports LACP-enabled.

2) When a manual or static aggregation group contains only one port, you cannot remove the port unless you remove the whole aggregation group.

1.2.1 Configuring a Manual Aggregation Group

You can create a manual aggregation group through the following operations. And you can remove an existing manual aggregation group. After that, all the ports in the group are removed from the group).

A port can only be manually added/removed to/from a manual aggregation group.

Follow these steps to configure a manual aggregation group:

To do…	Use the command…	Remarks
Enter system view	system-view	—
Create a manual aggregation group	link-aggregation group agg-id mode manual	Required
Add a group of ports to the manual aggregation group	link-aggregation interface-type interface-number to interface-type interface-number [ both ]	Optional
Configure a description for the aggregation group	link-aggregation group agg-id description agg-name	Optional By default, an aggregation group has no description.
Enter Ethernet port view	interface interface-type interface-num	—
Add the port to the aggregation group	port link-aggregation group agg-id	Required

1.2.2 Configuring a Static LACP Aggregation Group

You can create a static LACP aggregation group, or remove an existing static aggregation group (after that, the system will re-aggregate the original ports in the group to form one or more dynamic aggregation groups.).

A port can only be manually added/removed to/from a static aggregation group.

Follow these steps to configure a static LACP aggregation group:

To do…	Use the command…	Remarks
Enter system view	system-view	—
Create a static aggregation group	link-aggregation group agg-id mode static	Required
Configure a description for the aggregation group	link-aggregation group agg-id description agg-name	Optional By default, an aggregation group has no description.
Enter Ethernet port view	interface interface-type interface-number	—
Add the port to the aggregation group	port link-aggregation group agg-id	Required

& Note:

For a static LACP aggregation group or a manual aggregation group, you are recommended not to cross cables between the two devices at the two ends of the aggregation group. For example, suppose port 1 of the local device is connected to port 2 of the peer device. To avoid cross-connecting cables, do not connect port 2 of the local device to port 1 of the peer device. Otherwise, packets may be lost.

Note that:

l LACP cannot be enabled on a port in a manual aggregation group.

l You can add a LACP-enabled port to a manual aggregation group. In this case, the system will disable LACP on the port automatically. And, when you add a LACP-disabled port to a static aggregation group, the system will enable LACP on the port automatically.

1.2.3 Configuring a Dynamic LACP Aggregation Group

A dynamic LACP aggregation group is automatically created by the system based on LACP-enabled ports. The adding and removing of ports to/from a dynamic aggregation group are automatically accomplished by LACP.

You need to enable LACP on the ports whom you want to participate in dynamic aggregation of the system, because, only when LACP is enabled on those ports at both ends, can the two parties reach agreement in adding/removing ports to/from dynamic aggregation groups.

& Note:

LACP cannot be enabled on a port of a manual aggregation group.

Follow these steps to configure a dynamic LACP aggregation group:

To do…	Use the command…	Remarks
Enter system view	system-view	—
Configure a description for an aggregation group	link-aggregation group agg-id description agg-name	Optional By default, an aggregation group has no description.
Configure the system priority	lacp system-priority system-priority	Optional By default, the system priority is 32,768.
Enter Ethernet port view	interface interface-type interface-number	—
Enable LACP on the port	lacp enable	Required By default, LACP is disabled on a port.
Configure the port priority	lacp port-priority port-priority	Optional By default, the port priority is 32,768.

& Note:

If you use the save command to save the current configuration and then restart the device, the configured manual/static aggregation groups and their descriptions still exist, however, the dynamic aggregation groups will disappear and their descriptions cannot be restored.

1.3 Displaying and Maintaining Link Aggregation Configuration

To do…	Use the command…	Remarks
Display summary information of all aggregation groups	display link-aggregation summary	Available in any view
Display detailed information of a specific aggregation group	display link-aggregation verbose agg-id	Available in any view
Display the ID of the local device	display lacp system-id	Available in any view
Display link aggregation details of a specified port or port range	display link-aggregation interface interface-type interface-number \| [ to { interface-type interface-number ]	Available in any view
Clear LACP statistics about a specified port or port range	reset lacp statistics [ interface interface-type interface-number [ to interface-type interface-number ] ]	Available in user view

1.4 Link Aggregation Configuration Example

I. Network requirements

l Switch A connects to Switch B with three ports (Ethernet 2/0/1 through Ethernet 2/0/3). It is required that incoming/outgoing load between the two switch can be shared among the three ports.

l Adopt three different aggregation modes to implement link aggregation on the three ports between switch A and B.

II. Network diagram

Figure 1-1 Network diagram for link aggregation configuration

III. Configuration procedure

The following only lists the configuration on Switch A; you must perform the similar configuration on Switch B to implement link aggregation.

l Adopt the manual aggregation mode

# Create manual aggregation group 1.

<H3C> system-view

System View: return to User View with Ctrl+Z

[H3C] link-aggregation group 1 mode manual

# Add Ethernet 2/0/1 through Ethernet 2/0/3 to aggregation group 1.

[H3C] interface ethernet2/0/1

[H3C-Ethernet2/0/1] port link-aggregation group 1

[H3C-Ethernet2/0/1] interface ethernet2/0/2

[H3C-Ethernet2/0/2] port link-aggregation group 1

[H3C-Ethernet2/0/2] interface ethernet2/0/3

[H3C-Ethernet2/0/3] port link-aggregation group 1

l Adopt the static LACP aggregation mode

# Create static aggregation group 1.

[H3C] link-aggregation group 1 mode static

# Add Ethernet 2/0/1 through Ethernet 2/0/3 to aggregation group 1.

[H3C] interface ethernet2/0/1

[H3C-Ethernet2/0/1] port link-aggregation group 1

[H3C-Ethernet2/0/1] interface ethernet2/0/2

[H3C-Ethernet2/0/2] port link-aggregation group 1

[H3C-Ethernet2/0/2] interface ethernet2/0/3

[H3C-Ethernet2/0/3] port link-aggregation group 1

l Adopt the dynamic LACP aggregation mode

# Enable LACP on Ethernet 2/0/1 through Ethernet 2/0/3.

<H3C> system-view

[H3C] interface Ethernet2/0/1

[H3C-Ethernet2/0/1] lacp enable

[H3C-Ethernet2/0/1] interface Ethernet2/0/2

[H3C-Ethernet2/0/2] lacp enable

[H3C-Ethernet2/0/2] interface Ethernet2/0/3

[H3C-Ethernet2/0/3] lacp enable

Note that the three LACP-enabled ports can be aggregated into a dynamic aggregation group to implement load sharing only when they have the same basic configuration, rate and duplex mode.

H3C S7500 Series Operation Manual(Release 3100 Series)-(V1.04)

1.1.2 Introduction to LACP

1.1.4 Manual Aggregation Group

I. Introduction to manual aggregation group

II. Port status in manual aggregation group

III. Requirements on ports for manual aggregation

1.1.5 Static LACP Aggregation Group

I. Introduction to static LACP aggregation

II. Port status of static aggregation group

I. Introduction to dynamic LACP aggregation group

II. Port status of dynamic aggregation group

1.1.8 Aggregation Group Categories

1.3 Displaying and Maintaining Link Aggregation Configuration

I. Network requirements

II. Network diagram

III. Configuration procedure

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