Link Aggregation

The Link Aggregation feature helps to connect two or more physical links between two network devices without forming loops. Link Aggregation can be used between switches, servers and routers.

Link Aggregation provides the following advantages:

  • Increased bandwidth: Users can connect more than one physical link between devices to increase the link bandwidth.

  • Incremental bandwidth: Users can start aggregation with a fewer number of ports and then increase the number of ports in aggregation incrementally based on bandwidth requirements.

  • Redundancy: When one of the physical links fails, traffic is distributed over the other remaining links in the aggregation.

Figure 4. Link Aggregation

Note: The term "port channel" is used synonymously with aggregated links.

Creating Port Channels

Port channel creation involves two steps: the first step is creating the port channel interfaces and the second step is adding member ports to the port channel interfaces.

Creating Port Channel Interfaces

Follow the steps below to create port channel interfaces in SONiC:

Step

Command

Description

1

config portchannel add <portchannel_name>

Create a port channel interface.

  • portchannel_name: A port channel name in the format "PortChannelxxxx", replacing "xxxx" with a number of up to four digits (such as "PortChannel0001").

2

show interfaces portchannel

Display the configured port channel interfaces.

3

sudo config save –y

Optional: Save the current configuration to be part of the startup configuration.

The following example shows how to create a port channel interface.

admin@sonic: ~$ sudo config portchannel add PortChannel0001

admin@sonic: ~$ show interfaces portchannel

Flags:

A - active, I - inactive, Up - up, Dw - Down, N/A - not available,

 

S - selected, D - deselected, * - not synced

No.

Team Dev

Protocol

Ports

- - -

- - -

- - -

- - -

0001

PortChannel0001

LACP(A)(Dw)

 
Notes: 

  • It is recommended to use port channel names in the format "PortChannelxxxx", replacing "xxxx" with a number of up to four digits (such as "PortChannel0001").

  • If users specify any other name like "pc10", the command will succeed, but such names are not supported as those names are not printed properly in the show interface portchannel command. Therefore, nonstandard channel names are not recommended.

Adding Member Ports to Port Channels

Follow the steps below to add a member port to an existing port channel. A maximum of eight members shall be added to a port channel.

Step

Command

Description

1

config portchannel member add <portchannel_name> <member_portname>

Add a member port to an existing port channel.

  • portchannel_name: A port channel name in the format "PortChannelxxxx", replacing "xxxx" with a number of up to four digits (such as "PortChannel0001").

  • member_portname: Any interface name.

2

show interfaces portchannel

Display the configured port channel information.

3

sudo config save –y

Optional: Save the current configuration to be part of the startup configuration.

Note: Only ports of the same speed can be added to port channel interfaces. IP addresses must be removed before adding the port to the port channel.

The following example shows how to add a member port in a port channel:

  • Add an interface, Ethernet48, as a member port in PortChannel0001:

    admin@sonic: ~$ sudo config portchannel member add PortChannel0001 Ethernet48

  • When there is no LACP in a peer:

    admin@sonic: ~$ show interface portchannel

    Flags:

    A - active, I - inactive, Up - up, Dw - Down, N/A - not available,

     

    S - selected, D - deselected, * - not synced

    No.

    Team Dev

    Protocol

    Ports

    - - -

    - - -

    - - -

    - - -

    0001

    PortChannel0001

    LACP(A)(Dw)

    Ethernet48(D)

    admin@sonic: ~$ sudo config portchannel member add PortChannel0001 Ethernet52

  • When there is LACP in a peer:

    admin@sonic: ~$ show interface portchannel

    Flags:

    A - active, I - inactive, Up - up, Dw - Down, N/A - not available,

     

    S - selected, D - deselected, * - not synced

    No.

    Team Dev

    Protocol

    Ports

    - - -

    - - -

    - - -

    - - -

    0001

    PortChannel0001

    LACP(A)(Dw)

    Ethernet52(D) Ethernet48(D)

Removing Member Ports from a Port Channel

Follow the steps below to remove a member port from a port channel.

Step

Command

Description

1

config portchannel member del <portchannel_name> <member_portname>

Remove a member port from a port channel.

  • portchannel_name: A port channel name in the format "PortChannelxxxx", replacing "xxxx" with a number of up to four digits (such as "PortChannel0001").

  • member_portname: Any interface name.

2

show interfaces portchannel

Display the configured port channel information.

3

sudo config save –y

Optional: Save the current configuration to be part of the startup configuration.

The following examples show how to delete a member port from a port channel.

admin@sonic: ~$ sudo config portchannel member del PortChannel0001 Ethernet48

admin@sonic: ~$ sudo config portchannel member del PortChannel0001 Ethernet52

admin@sonic: ~$ show interface portchannel

Flags:

A - active, I - inactive, Up - up, Dw - Down, N/A - not available,

 

S - selected, D - deselected, * - not synced

No.

Team Dev

Protocol

Ports

- - -

- - -

- - -

- - -

0001

PortChannel0001

LACP(A)(Dw)

 

Removing Port Channels

Follow the steps below to remove port channels from SONiC.

Step

Command

Description

1

config portchannel member del <portchannel_name> <member_portname>

Remove a member port from a port channel.

  • portchannel_name: A port channel name in the format "PortChannelxxxx", replacing "xxxx" with a number of up to four digits (such as "PortChannel0001").

2

show interfaces portchannel

Display the configured port channel information.

3

sudo config save –y

Optional: Save the current configuration to be part of the startup configuration.

The following example shows how to remove a port channel.

admin@sonic: ~$ sudo config portchannel del PortChannel0001

admin@sonic: ~$ show interface portchannel

Flags:

A - active, I - inactive, Up - up, Dw - Down, N/A - not available,

 

S - selected, D - deselected, * - not synced

No.

Team Dev

Protocol

Ports

- - -

- - -

- - -

- - -

Note: The port channel cannot be deleted when there is a member in it. Remove the member ports before deleting a port channel.

Link Aggregation Configuration Example

Configure the SONiC switch as shown in the figure below.

  • Aggregate ports Ethernet48 and Ethernet49 in port channel PortChannel0004. Also configure this aggregation as a tagged interface with VLAN 20.

  • Aggregate ports Ethernet50 and Ethernet51 in port channel PortChannel0100. Configure this aggregation as an untagged port on VLAN 10.

Figure 5. Link Aggregation

  1. Create VLANs 10 and 20 first.

    admin@sonic: ~$ sudo config vlan add 10

    admin@sonic: ~$ sudo config vlan add 20

  2. Create port channel PortChannel0004, adding Ethernet48 and Ethernet49 as members.

    admin@sonic: ~$ sudo config portchannel add PortChannel0004

    admin@sonic: ~$ sudo config portchannel member add PortChannel0004 Ethernet48

    admin@sonic: ~$ sudo config portchannel member add PortChannel0004 Ethernet49

  3. Add port channel PortChannel0100 as a tagged member for VLAN 20.

    admin@sonic: ~$ sudo config vlan member add 20 PortChannel0004

  4. Create port channel PortChannel0100, adding Ethernet50 an Ethernet51 as members.

    admin@sonic: ~$ sudo config portchannel add PortChannel0100

    admin@sonic: ~$ sudo config portchannel member add PortChannel0100 Ethernet50

    admin@sonic: ~$ sudo config portchannel member add PortChannel0100 Ethernet51

  5. Add port channel PortChannel0004 as an untagged member for VLAN 10.

    admin@sonic: ~$ sudo config vlan member add -u 10 PortChannel0100

    admin@sonic: ~$ sudo interface portchannel

    Flags:

    A - active, I - inactive, Up - up, Dw - Down, N/A - not available, S - selected, D - deselected, * - not synced

    No.

    Team Dev

    Protocol

    Ports

     

     

    - - -

    - - -

    - - -

    - - -

     

     

    0001

    PortChannel0001

    LACP(A)(Dw)

    Ethernet48(D) Ethernet49(D)

     

    0004

    PortChannel0004

    LACP(A)(Dw)

    Ethernet50(D) Ethernet51(D)

     

    0100

    PortChannel0100

    LACP(A)(Dw)

     

     

     

    admin@sonic: ~$ show vlan config

    Name

    VID

    Member

    Mode

     

     

    - - -

    - - -

    - - -

    - - -

     

     

    Vlan10

    10

    Ethernet1

    untagged

     

     

    Vlan10

    10

    Ethernet2

    untagged

     

     

    Vlan10

    10

    Ethernet3

    untagged

     

     

    Vlan10

    10

    Ethernet5

    tagged

     

     

    Vlan10

    10

    Ethernet6

    tagged

     

     

    Vlan10

    10

    Ethernet7

    tagged

     

     

    Vlan10

    10

    PortChannel0100

    untagged

     

     

    Vlan20

    20

    Ethernet4

    tagged

     

     

    Vlan20

    20

    Ethernet5

    tagged

     

     

    Vlan20

    20

    Ethernet6

    tagged

     

     

    Vlan20

    20

    Ethernet7

    tagged

     

     

    Vlan20

    20

    PortChannel0004

    tagged

     

     

    Vlan30

    30

    Ethernet4

    tagged

     

     

    Vlan30

    30

    Ethernet5

    tagged

     

     

    Vlan30

    30

    Ethernet6

    tagged

     

     

    Vlan30

    30

    Ethernet7

    tagged

     

     

    Vlan100

    100

     

     

     

     

    Vlan200

    200

     

     

     

     

    admin@sonic: ~$ show vlan brief

    - - -

    - - -

    - - -

    - - -

    - - -

    - - -

    VLAN ID

    IP Address

    Ports

    Port Tagging

    Proxy ARP

    DHCP Helper Address

    - - -

    - - -

    - - -

    - - -

    - - -

    - - -

    10

     

    Ethernet1

    untagged

    disabled

     

     

     

    Ethernet2

    untagged

     

     

     

     

    Ethernet3

    untagged

     

     

     

     

    Ethernet5

    tagged

     

     

     

     

    Ethernet6

    tagged

     

     

     

     

    Ethernet7

    tagged

     

     

     

     

    PortChannel0100

    untagged

     

     

    - - -

    - - -

    - - -

    - - -

    - - -

    - - -

    20

     

    Ethernet4

    tagged

    disabled

     

     

     

    Ethernet5

    tagged

     

     

     

     

    Ethernet6

    tagged

     

     

     

     

    Ethernet7

    tagged

     

     

     

     

    PortChannel0004

    tagged

     

     

    - - -

    - - -

    - - -

    - - -

    - - -

    - - -

    30

     

    Ethernet4

    tagged

    disabled

     

     

     

    Ethernet5

    tagged

     

     

     

     

    Ethernet6

    tagged

     

     

     

     

    Ethernet7

    tagged

     

     

    - - -

    - - -

    - - -

    - - -

    - - -

    - - -

    100

     

     

     

    disabled

     

    - - -

    - - -

    - - -

    - - -

    - - -

    - - -

    200

     

     

     

    disabled

     

    - - -

    - - -

    - - -

    - - -

    - - -

    - - -