15. Link aggregation of layer 2 Technology (LACP)-Ethernet Channel

Link aggregation is to bundle multiple physical ports together into a logical link, which can increase link bandwidth. And link redundancy, when multiple physical interfaces are bundled together, if one of the lines fails, the link can continue to work.

Link aggregation method:

v Static Trunk: Bundles multiple physical links together to form a link group.

v Dynamic LACP: LACP link aggregation control protocol. When the LACP protocol is activated, LACP notifies its own system priority, system MAC address, port priority and port number through LACP DU. After receiving the information, the peer compares these information with its own attributes and automatically selects the port that can be aggregated.

Static bundling rules: Bundled interfaces must be the same VLAN, interfaces must have the same rate and duplex mode, and trunking must occur on the bundled interfaces.

Negotiation of LACP: Since the maximum number of ports in a dynamic aggregation group is limited, the LACP protocol selects ports to join by rules.

LACP election rules:

v Compare system priority + system MAC address and select the end with the lower ID.

v Compare port priority + port number and select the end with the lower port ID.

LACP's mode of operation:

Passive mode: LACPDU message will not be sent actively, passive response.

v Active mode: actively send LACPDU message, actively send.

CISCO Cisco Link Aggregation Command:

command

described

(config)# interface range f0/0 -3

Access to multiple interfaces simultaneously

(config-if-range)# channel-group 1 mode on

Static bundling forms Ethernet channels

(config)# interface port-channel 1

Enter Bundling Interface

(config-if)# switchport trunk encapsulation dot1q

Trunk Encapsulation Protocol for Setting Bundling Interface

(config-if)# switchport mode trunk

Trunk on the bundle interface

Note: The channel formed by bundling interfaces is called Ethernet Channel.

Huawei H3C Link Aggregation Command:

command

described

[huawei] interface eth-trunk 1

Create and Enter-Link Aggregation Interface

[huawei] interface e0/0/1 to e0/0/4

Access to multiple physical interfaces simultaneously

[huawei- e0/0/1 to e0/0/4] eth-trunk 1

Adding multiple physical interfaces to a link aggregation interface

[huawei-Eth-Trunk] port link-type trunk

Trunk from link aggregation port

[huawei-Eth-Trunk] port trunk allow-pass vlan10

Allow VLAN10 to pass

[huawei] display trunkmembership eth-trunk 1

View link aggregation port information

[huawei] display eth-trunk 1

View link aggregation port member information