Arista EOS Port-Channel & LACP Configuration Guide

Link aggregation on Arista EOS turns several physical Ethernet ports into one logical port channel, either statically or dynamically through LACP. Because the port channel is a first-class interface on EOS, you configure VLANs, SVIs or routed addresses directly on it, and the member ports simply join a channel group. This guide covers the channel-group modes, minimum links, LACP fallback, load-balancing profiles and the show commands you need to build and verify an EOS port channel.

Creating a Port Channel with LACP

Enter the member interfaces as a range and assign them to a channel group with a mode. active sends LACP PDUs and negotiates with the peer; passive only responds; on forces the channel without LACP (static). Two passive ends never form a bundle, so at least one side must be active.

switch(config)# interface ethernet 1-2
switch(config-if-Et1-2)# channel-group 10 mode active
switch(config-if-Et1-2)# exit
switch(config)# interface port-channel 10
switch(config-if-Po10)# switchport trunk allowed vlan 10,20,30
switch(config-if-Po10)# switchport mode trunk
switch(config-if-Po10)# no shutdown

Members can be added later to the same group; EOS applies the channel-group statement to each interface in the range:

switch(config)# interface ethernet 7-10
switch(config-if-Et7-10)# channel-group 10 mode active

Minimum Links and LACP Fallback

Port channels can require a minimum number of member links or a minimum aggregate speed before the bundle comes up, which protects against a degraded bundle carrying production traffic:

switch(config)# interface port-channel 13
switch(config-if-Po13)# port-channel min-links 4
switch(config-if-Po13)# port-channel speed minimum 100 gbps

EOS also supports LACP fallback for devices such as servers or PXE boot targets that need simple connectivity before they are ready to negotiate LACP. With static fallback the port channel keeps one active member while the others wait in standby until a LACP PDU arrives; with individual fallback all members act as independent switch ports. Fallback prevents a booting host with a single active NIC from being stranded without a link.

LACP Port Priority and Load Balancing

When the channel has more eligible members than the peer can bundle, EOS puts the interfaces with the higher LACP port-priority numbers into standby first (the default priority is 32768, range 0-65535):

switch(config)# interface ethernet 4
switch(config-if-Et4)# lacp port-priority 1000

Traffic distribution across the members is controlled by a load-balance profile. The default profile uses standard fields; you can build custom profiles from src-ip, dst-ip, src-port, dst-port, protocol or dscp and attach them to a port channel:

switch(config)# load-balance policies
switch(config-load-balance-policies)# load-balance sand profile myLB
switch(config-sand-load-balance-profile-myLB)# fields ip src-ip protocol dst-port
switch(config)# interface port-channel 10
switch(config-if-Po10)# port-channel load-balance sand profile myLB

Verification Commands

switch# show port-channel 10
switch# show port-channel summary
switch# show lacp 10 internal
switch# show lacp 10 neighbor
switch# show lacp 10 peer
switch# show interfaces port-channel 10

In the LACP output, look for the member state letters: S = short timeout, G = aggregable, I = individual, C = collecting, D = distributing. A healthy member shows as Bundled with ALGs+CD state; if a member shows as individual or standby, check the peer configuration, LACP mode, and port priority. For the bigger picture of building redundancy on EOS, see our runbooks on Arista EOS VLAN trunk and port-channel configuration and Arista EOS MLAG, plus the multi-vendor view in our Dell OS10 port-channel guide.

原文链接：https://arista.com/en/um-eos/eos-port-channels-and-lacp