LAG (Link Aggregation) Follow

Example: Establish LAG (Link Aggregation)

Restriction:

1. Both community SONiC and ecSONiC support only LACP. (Does NOT support static link aggregation)
2. LACP is from open source project - teamd in SONiC. It follows IEEE802.3ad and supports LACP only for front physical ports and breakout ports.
3. Before LACP establish, the LAG blocks all packets. (LACP fallback = False)
4. SONiC LACP rate(LACP PDU interval) is 30 seconds(slow mode) in default configuration. And it's NOT configurable.  
5. SONiC Fast-Reboot(Fast-Reload) requires LACP slow mode for all LAG interface. (https://github.com/Azure/SONiC/wiki/Fast-Reboot)

Reference model:

• Switch model name:  All
• Edgecore SONiC version: SONiC.Edgecore-SONiC_20201123_130028_ec202006_74

Topology:

Procedure :

Steps 1. Checking the port configuration

Here's the command to check the port configuration.

admin@sonic:~$ show vlan brief 
admin@sonic:~$ show ip interfaces
admin@sonic:~$ show interfaces status

Caution: have to remove VLAN and IP address from the LAG member ports before LAG Establish.  Refer to the following articles.

1. VLAN
2. IP Address

Steps 2. Create a PortChannel interface (Default LACP fallback = False)

admin@sonic:~$ sudo config portchannel add PortChannel1

(Optional) LACP fallback = True configuration:

Caution:

1. If you'd like to change Fallback status from False to True and vice versa, please delete the port channel and create it again with Fallback setting. Otherwise, the fallback setting won't take effect.

admin@sonic:~$ sudo config portchannel add PortChannel1 --fallback=true

Steps 3. Add member ports to PortChannel interface

admin@sonic:~$ sudo config portchannel member add PortChannel1 Ethernet48        
admin@sonic:~$ sudo config portchannel member add PortChannel1 Ethernet52

Caution: Please be sure the port interfce name is correct, in current version it didn't have error handling when your port name is incorrectly.

Steps 4. Save the setting to config_db.json

admin@sonic:~$ sudo config save -y

Steps 5. Check the appended setting.

admin@sonic:/etc/sonic$ sudo vi config_db.json
{
    ...
   "PORTCHANNEL": {
        "PortChannel1": {
            "admin_status": "up",
            "mtu": "9100"
        }
    },
    "PORTCHANNEL_MEMBER": {
        "PortChannel1|Ethernet48": {},
        "PortChannel1|Ethernet52": {}
    },
    ...
}

Steps 6. Check the setting status on PortChannel.

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
-----  ------------  -----------  ---------------------------
    1  PortChannel1  LACP(A)(Up)  Ethernet52(S) Ethernet48(S)

 If you see there are no port members (N/A), please return to Step 1.

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
-----  ------------  -----------  -------
    1  PortChannel1  LACP(A)(Dw)  N/A

 Steps 7. Check the interface status

admin@sonic:~$ show interfaces status | grep "Ethernet48\|Ethernet52\|PortChannel"
  Ethernet48      77,78,79,80     100G   9100     hundredGigE49  PortChannel1      up       up  QSFP28 or later         N/A
  Ethernet52      85,86,87,88     100G   9100     hundredGigE50  PortChannel1      up       up  QSFP28 or later         N/A
PortChannel1              N/A     200G   9100               N/A        routed      up       up              N/A         N/A