Dell Networking SONiC Static and LACP PortChannel
Summary: This article explains Static and LACP PortChannel in switches running Dell Networking SONiC OS. This article does not cover MC-LAG. This article uses a switch running Dell SONiC 4.1.
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Instructions
Prerequisites of the article
We are using standard interface naming in the configuration. To know more regarding various interface naming modes in Dell SONiC, refer Dell Networking S-Series: Basic Interface Configuration – SONIC 4.0
We are using the following topology for the article.
The interfaces to be added in the PortChannel, Eth 1/1, 1/2, and 1/3 must be configured for the same for speed, duplex, and MTU.
Index
What is a Portchannel?
Points to remember
Static PortChannel or ON mode
LACP PortChannel or Active mode
Minimum Links
MTU
What is a Portchannel?
A port channel is a set of one or more links that can be aggregated together to form a bonded channel (Link Aggregation Group or LAG or PortChannel).
Benefits of creating a PortChannel
- This provides redundancy, increased bandwidth, and better traffic load-balancing.
- A port channel aggregates the bandwidth of member links.
- If a member port fails, traffic is redirected to the remaining ports.
Types Of Port Channel
PortChannel can be configured as either
- Static PortChannel or ON mode
- LACP PortChannel or Active mode
Points to remember
- Use LLDP to verify link connections if the peer side supports LLDP
- The maximum number of interfaces in a PortChannel is 32
- A PortChannel can be configured as a L2 switchport mode and L3 routed port mode (Assign Ipv4/IPV6 address)
Below are the points to be remembered when adding an interface to a portchannel.
- All members must be the same interface type (such as Ethernet).
- All member interfaces must have the same Speed/Duplex/MTU.
- An interface must not contain nondefault L2/L3 configuration settings. Only the description and shutdown or no shutdown commands are supported.
- We cannot add an IP address or static MAC address to a member interface.
- We can assign an interface to only one port channel.
| Useful information |
Lets Cleanup the configuration of Eth 1/1 before adding the interface to portchannel DELLSONiC# show running-configuration interface Eth 1/1 ! interface Eth1/1 mtu 9100 speed 25000 shutdown switchport trunk allowed Vlan 1-4094 Lets execute default interface Eth1/1 DELLSONiC# configure DELLSONiC(config)# default interface Eth 1/1 We can see the interface configuration is defaulted DELLSONiC(config)# do show running-configuration interface Eth 1/1 ! interface Eth1/1 mtu 9100 speed 25000 shutdown DELLSONiC(config)# |
Static PortChannel or ON mode
Static PortChannel or ON mode is a simple way of configuring a PortChannel. This mode can be used if the connected device does not support LACP. A static LAG does not have any mechanism for exchange of aggregation information like LACP, hence it starts forwarding packets when one of its links comes up.
Configure PortChannel
Add Interfaces to Portchannel.
Configuration Syntax
| Configuration |
Explanation |
|---|---|
DELLSONiC(config)# interface Ethernet <number> |
Configure the interface. |
DELLSONiC(config)# interface range Ethernet <number-number> |
Optional: Configure a range of interfaces. |
DELLSONiC(conf-if-EthernetX)# channel-group <number> |
Define the PortChannel under the interface. |
DELLSONiC(conf-if-EthernetX)# no channel-group <number> |
Remove an interface from a portchannel. |
DELLSONiC(conf-if-EthernetX)# no shutdown |
Enable the interface. |
Sample Configuration
Lets Configure Portchannel 1 admin@DELLSONiC:~$ sonic-cli DELLSONiC# configure DELLSONiC(config)# interface PortChannel 1 mode on DELLSONiC(config-if-po1)# no shutdown DELLSONiC(config-if-po1)# exit Lets add interface Eth 1/1 as part of Portchannel 1 DELLSONiC(config)# interface Eth 1/1 DELLSONiC(config-if-Eth1/1)# channel-group 1 DELLSONiC(config-if-Eth1/1)# no shutdown DELLSONiC(config-if-Eth1/1)# exit Lets use interface range command to add interface Eth 1/2 and Eth 1/3 as part of Portchannel 1 DELLSONiC(config)# interface range Eth 1/2-1/3 %Info: Configuring only existing interfaces in range DELLSONiC(config-if-range-eth**)# channel-group 1 DELLSONiC(config-if-range-eth**)# no shutdown DELLSONiC(config-if-range-eth**)# end DELLSONiC# |
Use command show interface PortChannel <Portchannel id> and show PortChannel summary to verify status of PortChannel.
Sample Output
DELLSONiC# show interface PortChannel 1
PortChannel1 is up, line protocol is up, reason oper-up, mode Static
Hardware is PortChannel, address is XX:XX:XX:XX:XX:XX
Minimum number of links to bring PortChannel up is 1
Mode of IPV4 address assignment: not-set
Mode of IPV6 address assignment: not-set
Graceful shutdown: Disabled
MTU 9100
LineSpeed 75.0GB
Events:
all-links-down at 2023-09-19T17:24:05.257874Z
lacp-fail at 2023-09-19T17:25:15.406803Z
portchannel-up at 2023-09-19T17:25:15.417415Z
Members in this channel: Eth1/1
Members in this channel: Eth1/2
Members in this channel: Eth1/3
Last clearing of "show interface" counters: never
10 seconds input rate 2 packets/sec, 2968 bits/sec, 371 Bytes/sec
10 seconds output rate 0 packets/sec, 0 bits/sec, 0 Bytes/sec
Input statistics:
1320 packets, 243306 octets
0 Multicasts, 0 Broadcasts, 1320 Unicasts
0 error, 28 discarded
Output statistics:
818 packets, 190127 octets
0 Multicasts, 0 Broadcasts, 818 Unicasts
0 error, 0 discarded
Time since last interface status change: 00:03:23 |
DELLSONiC# show PortChannel summary
Flags(oper-status): D - Down U - Up (portchannel) P - Up in portchannel (members)
----------------------------------------------------------------------------------------------------------------------------
Group PortChannel Type Protocol Member Ports
----------------------------------------------------------------------------------------------------------------------------
1 PortChannel1 (U) Eth NONE Eth1/1(P)
Eth1/2(P)
Eth1/3(P) |
LACP PortChannel or Active mode
A port channel is a set of one or more links that can be aggregated together to form a bonded channel (Link Aggregation Group or LAG or port channel).
Link Aggregate Control Protocol (LACP) uses peer exchanges (LACPDU) across links to determine, on an ongoing basis, the aggregation capability of various links, and continuously provides the maximum level of aggregation capability achievable between a given pair of systems.
Configure PortChannel
Configuration Syntax
| Configuration |
Explanation |
|---|---|
admin@DELLSONiC:~$ sonic-cli |
Log in to DELL MF-CLI |
DELLSONiC# configure terminal |
Enter configuration mode. |
DELLSONiC(config)# interface PortChannel <number> |
Configure PortChannel as LACP active portchannel. |
sonic(config)# interface PortChannel <number> mode active |
(Optional) Configure PortChannel as LACP active PortChannel. You can specify an active mode. (default) |
DELLSONiC(conf-if-poX)# no shutdown |
Unshut the PortChannel. |
DELLSONiC(conf-if-poX)#exit |
Exit out of PortChannel. |
Add Interfaces to a Portchannel.
Configuration Syntax
| Configuration |
Explanation |
|---|---|
DELLSONiC(config)# interface Ethernet <number> |
Configure the interface. |
DELLSONiC(config)# interface range Ethernet <number-number> |
Optional: Configure a range of interfaces. |
DELLSONiC(conf-if-EthernetX)# channel-group <number> |
Define the PortChannel under the interface. |
DELLSONiC(conf-if-EthernetX)# no channel-group <number> |
Remove an interface from a portchannel. |
DELLSONiC(conf-if-EthernetX)# no shutdown |
Enable the interface. |
Sample Configuration
Lets Configure Portchannel 1 admin@DELLSONiC:~$ sonic-cli DELLSONiC# configure DELLSONiC(config)# interface PortChannel 1 DELLSONiC(config-if-po1)# no shutdown DELLSONiC(config-if-po1)# exit Lets add interface Eth 1/1 as part of Portchannel 1 DELLSONiC(config)# interface Eth 1/1 DELLSONiC(config-if-Eth1/1)# channel-group 1 DELLSONiC(config-if-Eth1/1)# no shutdown DELLSONiC(config-if-Eth1/1)# exit Lets use interface range command to add interface Eth 1/2 and Eth 1/3 as part of Portchannel 1 DELLSONiC(config)# interface range Eth 1/2-1/3 %Info: Configuring only existing interfaces in range DELLSONiC(config-if-range-eth**)# channel-group 1 DELLSONiC(config-if-range-eth**)# no shutdown DELLSONiC(config-if-range-eth**)# end DELLSONiC# |
Use command show interface PortChannel <Portchannel id> and show PortChannel summary to verify status of PortChannel.
Sample Output
DELLSONiC# show interface PortChannel 1
PortChannel1 is up, line protocol is up, reason oper-up, mode LACP
Hardware is PortChannel, address is XX:XX:XX:XX:XX:XX
Minimum number of links to bring PortChannel up is 1
Mode of IPV4 address assignment: not-set
Mode of IPV6 address assignment: not-set
Fallback: Disabled
Graceful shutdown: Disabled
MTU 9100
LineSpeed 75.0GB
Events:
all-links-down at 2023-09-19T16:19:23.406682Z
lacp-fail at 2023-09-19T16:37:02.782825Z
portchannel-up at 2023-09-19T16:37:42.564118Z
LACP mode ACTIVE interval SLOW priority 65535 address XX:XX:XX:XX:XX:XX
Members in this channel: Eth1/1(Selected)
LACP Actor port 1 address XX:XX:XX:XX:XX:XX key 1
LACP Partner port 1 address XX:XX:XX:XX:XX:XX key 1
Members in this channel: Eth1/2(Selected)
LACP Actor port 2 address XX:XX:XX:XX:XX:XX key 1
LACP Partner port 2 address XX:XX:XX:XX:XX:XX key 1
Members in this channel: Eth1/3(Selected)
LACP Actor port 3 address XX:XX:XX:XX:XX:XX key 1
LACP Partner port 3 address XX:XX:XX:XX:XX:XX key 1
Last clearing of "show interface" counters: never
10 seconds input rate 0 packets/sec, 0 bits/sec, 0 Bytes/sec
10 seconds output rate 0 packets/sec, 0 bits/sec, 0 Bytes/sec
Input statistics:
107 packets, 20173 octets
0 Multicasts, 0 Broadcasts, 107 Unicasts
0 error, 16 discarded
Output statistics:
209 packets, 34421 octets
0 Multicasts, 0 Broadcasts, 209 Unicasts
0 error, 0 discarded
Time since last interface status change: 00:02:04 |
DELLSONiC# show PortChannel summary
Flags(oper-status): D - Down U - Up (portchannel) P - Up in portchannel (members)
----------------------------------------------------------------------------------------------------------------------------
Group PortChannel Type Protocol Member Ports
----------------------------------------------------------------------------------------------------------------------------
1 PortChannel1 (U) Eth LACP Eth1/1(P)
Eth1/2(P)
Eth1/3(P) |
Minimum Links
We can configure the Minimum number of links to bring Port-channel up using command min-links. The default value is 0.
Sample Configuration
admin@DELLSONiC:~$ sonic-cli DELLSONiC# configure DELLSONiC(config)# interface PortChannel 1 DELLSONiC(config-if-po1)# min-links 2 DELLSONiC(config-if-po1)# end DELLSONiC# |
Sample Output
DELLSONiC# show PortChannel summary
Flags(oper-status): D - Down U - Up (portchannel) P - Up in portchannel (members)
----------------------------------------------------------------------------------------------------------------------------
Group PortChannel Type Protocol Member Ports
----------------------------------------------------------------------------------------------------------------------------
1 PortChannel1 (U) Eth LACP Eth1/1(P)
Eth1/2(P)
Eth1/3(P |
Consider port Eth 1/2, and Eth 1/3 link does down. Eth 1/1 is UP. Since only one link is up, and minimum link is 2 the PortChannel 1 goes down.
We can see that the Portchannel 1 is down and reason being minimum links.
Sample Output
DELLSONiC# show interface status (Output grepped for brevity) -------------------------------------------------------------------------------------------------------------------------------------- Name Description Oper Reason AutoNeg Speed MTU Alternate Name -------------------------------------------------------------------------------------------------------------------------------------- Eth1/1 - up oper-up off 25000 9100 Ethernet0 Eth1/2 - down admin-down off 25000 9100 Ethernet1 Eth1/3 - down admin-down off 25000 9100 Ethernet2 PortChannel1 - down min-links - 75000 9100 - |
MTU
We can configure MTU on a portchannel interface. Bellow is the key points that we must know before configuring the MTU in a PortChannel.
- Configure the MTU on the interface assigned to a port channel before we configure the port channel MTU.
- The default MTU of a PortChannel is 9100.
- All members of a port channel must have the same MTU value.
- Member interfaces with tagged VLANs must have a link MTU 4 bytes higher than untagged members to account for the packet tag.
- Ensure that the MTU of port channel member interfaces is greater than or equal to the port channel MTU.
- The system selects the lowest MTU value that is configured on the port channel or port channel members to be the port channel MTU.
Example
Consider the port channel contains tagged members with Link MTU of 1522 and IP MTU of 1500 and untagged members with Link MTU of 1518 and IP MTU of 1500.
The port channel’s Link MTU cannot be higher than 1518 bytes and its IP MTU cannot be higher than 1500 bytes.
NOTE:
|
Sample Output
Let us change the MTU of the PortChannel to 1500 (default is 9100)
DELLSONiC# configure DELLSONiC(config)# interface PortChannel 1 DELLSONiC(config-if-po1)# mtu 1500 DELLSONiC(config-if-po1)# end DELLSONiC# |
Sample Output
DELLSONiC# show interface PortChannel 1
PortChannel1 is up, line protocol is up, reason oper-up, mode LACP
Hardware is PortChannel, address is XX:XX:XX:XX:XX:XX
Minimum number of links to bring PortChannel up is 1
Mode of IPV4 address assignment: not-set
Mode of IPV6 address assignment: not-set
Fallback: Disabled
Graceful shutdown: Disabled
MTU 1500
LineSpeed 75.0GB
Events:
all-links-down at 2023-09-19T16:50:29.006155Z
lacp-fail at 2023-09-19T16:50:30.833807Z
portchannel-up at 2023-09-19T16:50:30.83887Z
LACP mode ACTIVE interval SLOW priority 65535 address XX:XX:XX:XX:XX:XX
Members in this channel: Eth1/1(Selected)
LACP Actor port 1 address XX:XX:XX:XX:XX:XX key 1
LACP Partner port 1 address XX:XX:XX:XX:XX:XX key 1
Members in this channel: Eth1/2(Selected)
LACP Actor port 2 address XX:XX:XX:XX:XX:XX key 1
LACP Partner port 2 address XX:XX:XX:XX:XX:XX key 1
Members in this channel: Eth1/3(Selected)
LACP Actor port 3 address XX:XX:XX:XX:XX:XX key 1
LACP Partner port 3 address XX:XX:XX:XX:XX:XX key 1
Last clearing of "show interface" counters: never
10 seconds input rate 0 packets/sec, 0 bits/sec, 0 Bytes/sec
10 seconds output rate 0 packets/sec, 0 bits/sec, 0 Bytes/sec
Input statistics:
274 packets, 59031 octets
0 Multicasts, 0 Broadcasts, 274 Unicasts
0 error, 19 discarded
Output statistics:
385 packets, 78115 octets
0 Multicasts, 0 Broadcasts, 385 Unicasts
0 error, 0 discarded
Time since last interface status change: 00:01:18 |
Affected Products
Enterprise SONiC Distribution, PowerSwitch E3200-ON Series, Dell EMC Networking N3200-ON, PowerSwitch S5212F-ON, PowerSwitch S5224F-ON, PowerSwitch S5232F-ON, PowerSwitch S5248F-ON, PowerSwitch S5296F-ON, PowerSwitch Z9264F-ON, PowerSwitch Z9332F-ON
, PowerSwitch Z9432F-ON
...
Article Properties
Article Number: 000217739
Article Type: How To
Last Modified: 28 Sep 2023
Version: 3
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